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1<rss xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:content="http://purl.org/rss/1.0/modules/content/" xmlns:atom="http://www.w3.org/2005/Atom" version="2.0">
2 <channel>
3 <title>Mitja Felicijan's posts</title>
4 <link>https://mitjafelicijan.com</link>
5 <description>You do not learn by relaxing. You learn by violently assaulting your problem until it surrenders its mysteries to you.</description>
6 <language>en-us</language>
7
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24 <item>
25 <title>Who knows what the world will look like tomorrow</title>
26 <link>https://mitjafelicijan.com/who-knows-what-the-world-will-look-like-tomorrow.html</link>
27 <pubDate>Sat, 08 Jul 2023 18:49:07 &#43;0200</pubDate>
28 <guid>https://mitjafelicijan.com/who-knows-what-the-world-will-look-like-tomorrow.html</guid>
29 <description>This site has gone through a lot of changes over the years.</description>
30 <content:encoded>&lt;p&gt;This site has gone through a lot of changes over the years. From being written
31in Flask and Bottle to moving on to static site generators. I have used and
32tested probably 10s of them my now. From homebrew solutions to the biggest and
33the baddest. From Bash scripts to Node.js disasters. I&#39;ve seen some things, no
34doubt. Not all bad.&lt;/p&gt;
35&lt;p&gt;I have been closely observing the web and where the trends are going, and I
36don&#39;t like what I see. Instead of internet being this weird place where
37experimentation is happening, it all became stale and formulized. Boring,
38actually. Really boring. And sad. Where is that old, revolutionary FU spirit I
39remember? It&#39;s still there, I know. But it&#39;s being drowned by the voices of
40mediocrity and formulaic boredom.&lt;/p&gt;
41&lt;p&gt;It almost feels like that the internet stopped for 10 years and only now
42something has started happening. With all the insanity around the world. People
43hating people without actual reasons, just because it&#39;s fashionable to hate and
44crowd is saying so. Sad state of affairs.&lt;/p&gt;
45&lt;p&gt;All this is contributing to this overall negativity masked as apathy. Everybody
46walking in lockstep. Instead of being creative and bold, we are just
47re-inventing the world and making the same mistakes. Maybe, just maybe, some
48things are good enough and there is no need to try to be too smart for our own
49good. After N-attempts, maybe something should click inside our heads to maybe
50say: &amp;quot;This thing, opinion, etc. is actually really good, and even after several
51attempts it still holds.&amp;quot;&lt;/p&gt;
52&lt;p&gt;The older I get, the more careful I am of my own thoughts and why I think the
53way I think. More and more, I try to understand people with opposite
54opinions. Far from perfect, but closer to bearable. And then I see people
55hearing or reading a thing on internet and let&#39;s fucking goooooo! Strong
56opinions are a sign of a weak and uneducated mind. I am more and more sure of
57this.&lt;/p&gt;
58&lt;p&gt;It&#39;s gotten to a point where you can with great certainty deduce a person&#39;s
59personality based on one or two opinions. How boring have we become. No wonder
60people can&#39;t talk to each other. These would be very quick conversations anyway.&lt;/p&gt;
61&lt;p&gt;I just got remembered of a song, &lt;a href=&#34;https://www.youtube.com/watch?v=s_nc1IVoMxc&#34;&gt;&amp;quot;Hi
62Ren&amp;quot;&lt;/a&gt;. The ending talks about being
63stiff and not being able to dance. Such an amazing metaphor. And we as people
64have gone so far, we can&#39;t even walk or even crawl normally anymore. We have
65forgotten that the most beautiful things in life have a great deal of
66uncertainty about them. We want instant gratification. Not only that, but we
67want absolute obedience. Complete control over others, because we have zero
68control of ourselves. And all the lies we could tell ourselves will not help us
69out of this situation.&lt;/p&gt;
70&lt;p&gt;It is funny how I catch myself from time to time being a complete idiot. It&#39;s
71like having an outer body experience. I can see myself being an idiot, and
72cannot stop myself. It serves as a learning lesson to stop before speaking. To
73think before saying. And to crawl before walking.&lt;/p&gt;
74&lt;p&gt;So there is still time. We can dance once more. All we need to do is stop for a
75second. Me and you. Us two is a start. Let&#39;s not try to change the world, but
76rather nudge ourselves just a tiny bit. And if we only did that?! Just
77imagine. Each of us nudged ourselves a small, tiny bit, the world would heal. If
78we would just put down the phones and ignored Internet for a day or two. Put
79visiting websites that feed on us on hold. Listened to just one sentence and try
80to understand it from a person who we completely disagree with. I truly believe
81that this is possible.&lt;/p&gt;
82&lt;p&gt;Life is about suffering and joy. And instead of wishing suffering on others and
83excepting joy for yourselves, we should for a brief moment want suffering for
84ourselves and wish joy on others. Wouldn&#39;t that be an amazing sight to see?&lt;/p&gt;
85&lt;p&gt;I caught myself hating on Rust. And I deeply thought about it afterward. Why did
86I do it? It is obviously not for me. So why the hell was I being so negative
87towards it? I think that I know the answer. I was negative because that is
88easy. Because it&#39;s much easier to hate on things than to say to yourself: &amp;quot;Well,
89you know what? This is not for me. I will focus on creation and not
90destruction. This is who I want to be. This is what fills me with joy and
91purpose.&amp;quot; Where joy is keeping me happy and purpose scares the shit out of me
92and keeps me honest. This is who I want to be. Admit to myself when I am wrong
93and accept the faults that I have without reservation and with courage march on.&lt;/p&gt;
94&lt;p&gt;I just realized that this blog post is a sort of therapy for me. It&#39;s
95cathartic. Going thought the history of this site and remembering all the
96decisions and annoyances that came with it. When I was cursing at the tools. And
97time moved on, and the site is still here. It serves as a reminder that
98perseverance wins at the end. If we just let things go.&lt;/p&gt;
99&lt;p&gt;This came with a decision that simplifying life and removing all the unnecessary
100negativity is key. Rather than worrying about what the internet is saying, what
101the world is trying to take from you, you are the only one who can say no. And
102create instead of destroy.&lt;/p&gt;
103&lt;p&gt;I don&#39;t have an ending for this post, so I will say this. We live in the most
104amazing times in the recorded history, and we should be internally grateful for
105it. Create and study, this should be my mantra. Just create and let the world
106happen. And when you feel yourself to be too certain, stop and check how deep in the
107shit you are already. Strong opinions are a sign of a weak and uneducated
108mind. Hate and disdain is for the weak.&lt;/p&gt;
109</content:encoded>
110 </item>
111
112
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114 <item>
115 <title>Bringing all of my projects together under one umbrella</title>
116 <link>https://mitjafelicijan.com/bringing-all-of-my-projects-together-under-one-umbrella.html</link>
117 <pubDate>Sat, 01 Jul 2023 18:49:07 &#43;0200</pubDate>
118 <guid>https://mitjafelicijan.com/bringing-all-of-my-projects-together-under-one-umbrella.html</guid>
119 <description>What is the issue anyway?</description>
120 <content:encoded>&lt;h2 id=&#34;what-is-the-issue-anyway&#34;&gt;What is the issue anyway?&lt;/h2&gt;
121&lt;p&gt;Over the years, I have accumulated a bunch of virtual servers on my
122&lt;a href=&#34;https://www.digitalocean.com/&#34;&gt;DigitalOcean&lt;/a&gt; account for small experimental
123projects I dabble in. And this has resulted in quite a bill. I mean, I wouldn&#39;t
124care if these projects were actually being used. But there were just being there
125unused and wasting resources. Which makes this an unnecessary burden for me.&lt;/p&gt;
126&lt;p&gt;Most of them are just small HTML pages that have an endpoint or two to read data
127from or to, and for that reason I wrote servers left and right. To be honest,
128all of those things could have been done with &lt;a href=&#34;https://en.wikipedia.org/wiki/Common_Gateway_Interface&#34;&gt;CGI
129scripts&lt;/a&gt; and that would
130have been more than enough.&lt;/p&gt;
131&lt;p&gt;Recently, I decided to stop language hopping and focus on a simpler stack which
132includes C, Go and Lua. And I can accomplish all the things I am interested in.&lt;/p&gt;
133&lt;h2 id=&#34;finding-a-web-server-replacement&#34;&gt;Finding a web server replacement&lt;/h2&gt;
134&lt;p&gt;Usually I had &lt;a href=&#34;https://nginx.org/en/&#34;&gt;Nginx&lt;/a&gt; in front of these small web servers
135and I had to manage SSL certificates and all that jazz. I am bored with these
136things. I don&#39;t want to manage any of this bullshit anymore.&lt;/p&gt;
137&lt;p&gt;So the logical move forward was to find a solid alternative for this. I have
138ended up on &lt;a href=&#34;https://caddyserver.com/&#34;&gt;Caddy server&lt;/a&gt;. I&#39;ve used it in the past
139but kind of forgotten about it. What I really like about it is an ease of use
140and a bunch of out of the box functionalities that come with it.&lt;/p&gt;
141&lt;p&gt;These are the &lt;em&gt;pitch&lt;/em&gt; points from their website:&lt;/p&gt;
142&lt;ul&gt;
143&lt;li&gt;&lt;strong&gt;Secure by Default&lt;/strong&gt;: Caddy is the only web server that uses HTTPS by
144default. A hardened TLS stack with modern protocols preserves privacy and
145exposes MITM attacks.&lt;/li&gt;
146&lt;li&gt;&lt;strong&gt;Config API&lt;/strong&gt;: As its primary mode of configuration, Caddy&#39;s REST API makes
147it easy to automate and integrate with your apps.&lt;/li&gt;
148&lt;li&gt;&lt;strong&gt;No Dependencies&lt;/strong&gt;: Because Caddy is written in Go, its binaries are entirely
149self-contained and run on every platform, including containers without libc.&lt;/li&gt;
150&lt;li&gt;&lt;strong&gt;Modular Stack&lt;/strong&gt;: Take back control over your compute edge. Caddy can be
151extended with everything you need using plugins.&lt;/li&gt;
152&lt;/ul&gt;
153&lt;p&gt;I had just a few requirements:&lt;/p&gt;
154&lt;ul&gt;
155&lt;li&gt;Automatic SSL&lt;/li&gt;
156&lt;li&gt;Static file server&lt;/li&gt;
157&lt;li&gt;Basic authentication&lt;/li&gt;
158&lt;li&gt;CGI script support&lt;/li&gt;
159&lt;/ul&gt;
160&lt;p&gt;And the vanilla version does all of it, but CGI scripts. But that can easily be
161fixed with their modular approach. You can do this on their website and build a
162custom version of the server, or do it with Docker.&lt;/p&gt;
163&lt;p&gt;This is a &lt;code&gt;Dockerfile&lt;/code&gt; I used to build a custom server.&lt;/p&gt;
164&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;FROM&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; caddy:builder AS builder&lt;/span&gt;&lt;span style=&#34;&#34;&gt;
165&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;&#34;&gt;
166&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;&#34;&gt;&lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;RUN&lt;/span&gt; xcaddy build &lt;span style=&#34;color:#a31515&#34;&gt;\
167&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; --with github.com/aksdb/caddy-cgi&lt;span style=&#34;&#34;&gt;
168&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;&#34;&gt;
169&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;&#34;&gt;&lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;FROM&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; caddy:latest&lt;/span&gt;&lt;span style=&#34;&#34;&gt;
170&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;&#34;&gt;&lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;RUN&lt;/span&gt; apk add --no-cache nano&lt;span style=&#34;&#34;&gt;
171&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;&#34;&gt;
172&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;&#34;&gt;&lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;COPY&lt;/span&gt; --from=builder /usr/bin/caddy /usr/bin/caddy&lt;span style=&#34;&#34;&gt;
173&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;getting-rid-of-all-the-unnecessary-virtual-machines&#34;&gt;Getting rid of all the unnecessary virtual machines&lt;/h2&gt;
174&lt;p&gt;The next step was to get a handle on the number of virtual servers I have all
175over the place.&lt;/p&gt;
176&lt;p&gt;I decided to move all the projects and services into two main VMs:&lt;/p&gt;
177&lt;ul&gt;
178&lt;li&gt;personal server (still Nginx)
179&lt;ul&gt;
180&lt;li&gt;git server&lt;/li&gt;
181&lt;li&gt;static file server&lt;/li&gt;
182&lt;li&gt;personal blog&lt;/li&gt;
183&lt;/ul&gt;
184&lt;/li&gt;
185&lt;li&gt;projects server (Caddy server)
186&lt;ul&gt;
187&lt;li&gt;personal experiments&lt;/li&gt;
188&lt;li&gt;other projects&lt;/li&gt;
189&lt;/ul&gt;
190&lt;/li&gt;
191&lt;/ul&gt;
192&lt;p&gt;I will focus on projects&#39; server in this post since it&#39;s more interesting.&lt;/p&gt;
193&lt;h2 id=&#34;testing-cgi-scripts&#34;&gt;Testing CGI scripts&lt;/h2&gt;
194&lt;p&gt;The first thing I tested was how CGI scripts work under Caddy. This is
195particularly import to me because almost all of my experiments and mini projects
196need this to work.&lt;/p&gt;
197&lt;p&gt;To configure Caddy server, you must provide the server with a configuration
198file. By default, it&#39;s called &lt;code&gt;Caaddyfile&lt;/code&gt;.&lt;/p&gt;
199&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;{
200&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;order&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;cgi&lt;/span&gt; before &lt;span style=&#34;color:#a31515&#34;&gt;respond&lt;/span&gt;
201&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
202&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
203&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;font-weight:bold&#34;&gt;examples.mitjafelicijan.com&lt;/span&gt; {
204&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;cgi&lt;/span&gt; /bash-test &lt;span style=&#34;color:#a31515&#34;&gt;/opt/projects/examples/bash-test.sh&lt;/span&gt;
205&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;cgi&lt;/span&gt; /tcl-test &lt;span style=&#34;color:#a31515&#34;&gt;/opt/projects/examples/tcl-test.tcl&lt;/span&gt;
206&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;cgi&lt;/span&gt; /lua-test &lt;span style=&#34;color:#a31515&#34;&gt;/opt/projects/examples/lua-test.lua&lt;/span&gt;
207&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;cgi&lt;/span&gt; /python-test &lt;span style=&#34;color:#a31515&#34;&gt;/opt/projects/examples/python-test.py&lt;/span&gt;
208&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
209&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;root&lt;/span&gt; * &lt;span style=&#34;color:#a31515&#34;&gt;/opt/projects/examples&lt;/span&gt;
210&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;file_server&lt;/span&gt;
211&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
212&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;ul&gt;
213&lt;li&gt;The order is very important. Make sure that &lt;code&gt;order cgi before respond&lt;/code&gt; is at
214the top of the configuration file.&lt;/li&gt;
215&lt;li&gt;Also, when you run with Caddy v2, make sure you provide &lt;code&gt;adapter&lt;/code&gt; argument
216like this &lt;code&gt;/usr/bin/caddy run --watch --environ --config /etc/caddy/Caddyfile --adapter caddyfile&lt;/code&gt;. Otherwise, Caddy will try to use a different format for
217config file.&lt;/li&gt;
218&lt;/ul&gt;
219&lt;p&gt;I did a small batch of tests with &lt;a href=&#34;https://www.gnu.org/software/bash/&#34;&gt;Bash&lt;/a&gt;,
220&lt;a href=&#34;https://www.tcl-lang.org/&#34;&gt;Tcl&lt;/a&gt;, &lt;a href=&#34;https://www.lua.org/&#34;&gt;Lua&lt;/a&gt; and
221&lt;a href=&#34;https://www.python.org/&#34;&gt;Python&lt;/a&gt;. Here is a cheat sheet if you need it.&lt;/p&gt;
222&lt;p&gt;Let&#39;s get Bash out of the way first.&lt;/p&gt;
223&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;#!/usr/bin/bash
224&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;&lt;/span&gt;
225&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;printf &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Content-type: text/plain\n\n&amp;#34;&lt;/span&gt;
226&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
227&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;printf &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Hello from Bash\n\n&amp;#34;&lt;/span&gt;
228&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;printf &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;PATH_INFO [%s]\n&amp;#34;&lt;/span&gt; $PATH_INFO
229&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;printf &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;QUERY_STRING [%s]\n&amp;#34;&lt;/span&gt; $QUERY_STRING
230&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;printf &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;\n&amp;#34;&lt;/span&gt;
231&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
232&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; i in {0..9..1}; &lt;span style=&#34;color:#00f&#34;&gt;do&lt;/span&gt;
233&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; printf &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&amp;gt; %s\n&amp;#34;&lt;/span&gt; $i
234&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;done&lt;/span&gt;
235&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
236&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;exit 0
237&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;This one is for Tcl script.&lt;/p&gt;
238&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;#!/usr/bin/tclsh
239&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;
240&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;puts &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Content-type: text/plain\n&amp;#34;&lt;/span&gt;
241&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
242&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;puts &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Hello from Tcl\n&amp;#34;&lt;/span&gt;
243&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;puts &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;PATH_INFO \[$env(PATH_INFO)\]&amp;#34;&lt;/span&gt;
244&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;puts &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;QUERY_STRING \[$env(QUERY_STRING)\]&amp;#34;&lt;/span&gt;
245&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;puts &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&amp;#34;&lt;/span&gt;
246&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
247&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;{set&lt;/span&gt; i 0&lt;span style=&#34;color:#00f&#34;&gt;}&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;{&lt;/span&gt;$i &amp;lt; 10&lt;span style=&#34;color:#00f&#34;&gt;}&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;{&lt;/span&gt;incr i&lt;span style=&#34;color:#00f&#34;&gt;}&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;{&lt;/span&gt;
248&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; puts &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&amp;gt; $i&amp;#34;&lt;/span&gt;
249&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;}&lt;/span&gt;
250&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;And for all you Python enjoyers.&lt;/p&gt;
251&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;#!/usr/bin/python3&lt;/span&gt;
252&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
253&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; os
254&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
255&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Content-type: text/plain&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\n&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt;)
256&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
257&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Hello from Python&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\n&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt;)
258&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;PATH_INFO [&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;{}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;]&amp;#34;&lt;/span&gt;.format(os.environ[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;PATH_INFO&amp;#39;&lt;/span&gt;]))
259&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;QUERY_STRING [&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;{}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;]&amp;#34;&lt;/span&gt;.format(os.environ[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;QUERY_STRING&amp;#39;&lt;/span&gt;]))
260&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&amp;#34;&lt;/span&gt;)
261&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
262&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; i &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; range(10):
263&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&amp;gt; &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;{}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt;.format(i))
264&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;And for the final example, Lua.&lt;/p&gt;
265&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;#!/usr/bin/lua&lt;/span&gt;
266&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
267&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Content-type: text/plain&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\n&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt;)
268&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
269&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Hello from Lua&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\n&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt;)
270&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print(string.format(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;PATH_INFO [%s]&amp;#34;&lt;/span&gt;, os.getenv(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;PATH_INFO&amp;#34;&lt;/span&gt;)))
271&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print(string.format(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;QUERY_STRING [%s]&amp;#34;&lt;/span&gt;, os.getenv(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;QUERY_STRING&amp;#34;&lt;/span&gt;)))
272&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print()
273&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
274&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; i = 0, 9 &lt;span style=&#34;color:#00f&#34;&gt;do&lt;/span&gt;
275&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; print(string.format(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&amp;gt; %d&amp;#34;&lt;/span&gt;, i))
276&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;end&lt;/span&gt;
277&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;basic-authentication&#34;&gt;Basic authentication&lt;/h2&gt;
278&lt;p&gt;One thing was also to have an option for some sort of authentication, and
279something like &lt;a href=&#34;https://en.wikipedia.org/wiki/Basic_access_authentication&#34;&gt;Basic access
280authentication&lt;/a&gt; would
281be more than enough.&lt;/p&gt;
282&lt;p&gt;Thankfully, Caddy supports this out of the box already. Below is an updated
283example.&lt;/p&gt;
284&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;{
285&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;order&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;cgi&lt;/span&gt; before &lt;span style=&#34;color:#a31515&#34;&gt;respond&lt;/span&gt;
286&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
287&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
288&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;font-weight:bold&#34;&gt;examples.mitjafelicijan.com&lt;/span&gt; {
289&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;cgi&lt;/span&gt; /bash-test &lt;span style=&#34;color:#a31515&#34;&gt;/opt/projects/examples/bash-test.sh&lt;/span&gt;
290&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;cgi&lt;/span&gt; /tcl-test &lt;span style=&#34;color:#a31515&#34;&gt;/opt/projects/examples/tcl-test.tcl&lt;/span&gt;
291&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;cgi&lt;/span&gt; /lua-test &lt;span style=&#34;color:#a31515&#34;&gt;/opt/projects/examples/lua-test.lua&lt;/span&gt;
292&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;cgi&lt;/span&gt; /python-test &lt;span style=&#34;color:#a31515&#34;&gt;/opt/projects/examples/python-test.py&lt;/span&gt;
293&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
294&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;root&lt;/span&gt; * &lt;span style=&#34;color:#a31515&#34;&gt;/opt/projects/examples&lt;/span&gt;
295&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;file_server&lt;/span&gt;
296&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
297&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;basicauth&lt;/span&gt; * {
298&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;bob&lt;/span&gt; &lt;span style=&#34;&#34;&gt;$&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;2a&lt;/span&gt;&lt;span style=&#34;&#34;&gt;$&lt;/span&gt;14&lt;span style=&#34;&#34;&gt;$&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;/wCgaf9oMnmQa20txB76u.nI1AldGMBT/1J7fXCfgOiRShwz/JOkK&lt;/span&gt;
299&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
300&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
301&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;code&gt;basicauth *&lt;/code&gt; matches everything under this domain/sub-domain and protects it
302with Basic Authentication.&lt;/p&gt;
303&lt;ul&gt;
304&lt;li&gt;&lt;code&gt;bob&lt;/code&gt; is the username&lt;/li&gt;
305&lt;li&gt;&lt;code&gt;hash&lt;/code&gt; is the password&lt;/li&gt;
306&lt;/ul&gt;
307&lt;p&gt;To generate these passwords, execute &lt;code&gt;caddy hash-password&lt;/code&gt; and this will prompt
308you to insert a password twice and spit out a hashed password that you can put
309in your configuration file.&lt;/p&gt;
310&lt;p&gt;Restart the server and you are ready to go.&lt;/p&gt;
311&lt;h2 id=&#34;making-caddy-a-service-with-systemd&#34;&gt;Making Caddy a service with systemd&lt;/h2&gt;
312&lt;p&gt;After the tests were successful, I copied &lt;code&gt;caddy&lt;/code&gt; to &lt;code&gt;/usr/bin/caddy&lt;/code&gt; and copied
313&lt;code&gt;Caddyfile&lt;/code&gt; to &lt;code&gt;/etc/caddy/Caddyfile&lt;/code&gt;.&lt;/p&gt;
314&lt;p&gt;Now off to the systemd. Each systemd service requires you to create a service
315file.&lt;/p&gt;
316&lt;ul&gt;
317&lt;li&gt;I created a &lt;code&gt;/etc/systemd/system/caddy.service&lt;/code&gt; and put the following content
318in the file.&lt;/li&gt;
319&lt;/ul&gt;
320&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;[Unit]&lt;/span&gt;
321&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Description=&lt;span style=&#34;color:#a31515&#34;&gt;Caddy&lt;/span&gt;
322&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Documentation=&lt;span style=&#34;color:#a31515&#34;&gt;https://caddyserver.com/docs/&lt;/span&gt;
323&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;After=&lt;span style=&#34;color:#a31515&#34;&gt;network.target network-online.target&lt;/span&gt;
324&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Requires=&lt;span style=&#34;color:#a31515&#34;&gt;network-online.target&lt;/span&gt;
325&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
326&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;[Service]&lt;/span&gt;
327&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Type=&lt;span style=&#34;color:#a31515&#34;&gt;notify&lt;/span&gt;
328&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;User=&lt;span style=&#34;color:#a31515&#34;&gt;root&lt;/span&gt;
329&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Group=&lt;span style=&#34;color:#a31515&#34;&gt;root&lt;/span&gt;
330&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ExecStart=&lt;span style=&#34;color:#a31515&#34;&gt;/usr/bin/caddy run --environ --config /etc/caddy/Caddyfile --adapter caddyfile&lt;/span&gt;
331&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ExecReload=&lt;span style=&#34;color:#a31515&#34;&gt;/usr/bin/caddy reload --config /etc/caddy/Caddyfile --force --adapter caddyfile&lt;/span&gt;
332&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;TimeoutStopSec=&lt;span style=&#34;color:#a31515&#34;&gt;5s&lt;/span&gt;
333&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;LimitNOFILE=&lt;span style=&#34;color:#a31515&#34;&gt;1048576&lt;/span&gt;
334&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;LimitNPROC=&lt;span style=&#34;color:#a31515&#34;&gt;512&lt;/span&gt;
335&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;PrivateTmp=&lt;span style=&#34;color:#a31515&#34;&gt;true&lt;/span&gt;
336&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ProtectSystem=&lt;span style=&#34;color:#a31515&#34;&gt;full&lt;/span&gt;
337&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;AmbientCapabilities=&lt;span style=&#34;color:#a31515&#34;&gt;CAP_NET_ADMIN CAP_NET_BIND_SERVICE&lt;/span&gt;
338&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
339&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;[Install]&lt;/span&gt;
340&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;WantedBy=&lt;span style=&#34;color:#a31515&#34;&gt;multi-user.target&lt;/span&gt;
341&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;ul&gt;
342&lt;li&gt;You might need to reload systemd with &lt;code&gt;systemctl daemon-reload&lt;/code&gt;.&lt;/li&gt;
343&lt;li&gt;Then I enabled the service with &lt;code&gt;systemctl enable caddy.service&lt;/code&gt;.&lt;/li&gt;
344&lt;li&gt;And then I started the service with &lt;code&gt;systemctl start caddy.service&lt;/code&gt;.&lt;/li&gt;
345&lt;/ul&gt;
346&lt;p&gt;This was about all that I needed to do to get it running. Now I can easily add
347new subdomains and domains to the main configuration file and be done with
348it. No manual Let&#39;s Encrypt shenanigans needed.&lt;/p&gt;
349</content:encoded>
350 </item>
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370 <item>
371 <title>Re-Inventing Task Runner That I Actually Used Daily</title>
372 <link>https://mitjafelicijan.com/re-inventing-task-runner-that-i-actually-used-daily.html</link>
373 <pubDate>Wed, 31 May 2023 12:21:10 &#43;0200</pubDate>
374 <guid>https://mitjafelicijan.com/re-inventing-task-runner-that-i-actually-used-daily.html</guid>
375 <description>Couple of months ago I had this brilliant idea of re-inventing the wheel bymaking an alternative for make.</description>
376 <content:encoded>&lt;p&gt;Couple of months ago I had this brilliant idea of re-inventing the wheel by
377making an alternative for make. And so I went. Boldly into the battle. And to my
378big surprise my attempt resulted in not a completely useless piece of software.&lt;/p&gt;
379&lt;p&gt;My initial requirements were quite simple but soon grow into something more
380ambitious. And looking back I should have stuck to the simple version. My
381laziness was on my side this time though. Because I haven’t implemented some of
382the features I now realise I really didn’t need them and they would bog the
383whole program and make it be something it was never meant to be.&lt;/p&gt;
384&lt;p&gt;My basic requirements were following:&lt;/p&gt;
385&lt;ul&gt;
386&lt;li&gt;Syntax should be a tiny bit inspired by Rake and Rakefiles.&lt;/li&gt;
387&lt;li&gt;Should borrow the overall feel of a unit test experience.&lt;/li&gt;
388&lt;li&gt;Using something like Python would be a bit of an overkill.&lt;/li&gt;
389&lt;li&gt;The program must be statically compiled, so it can run on same architecture
390without libc, musl dependencies or things like that.&lt;/li&gt;
391&lt;li&gt;Install ruby for rake is a bit overkill and can not be done with certain
392really lightweight distributions like Alpine Linux. This tool would be usable
393on such lightweight systems for remote debugging.&lt;/li&gt;
394&lt;li&gt;I want to use it for more than just compiling things. I want to use it as an
395entry-point into a project, and I want this to help me indirectly document the
396project as well.&lt;/li&gt;
397&lt;li&gt;It should be an abstraction over bash shell or the default system shell.
398&lt;ul&gt;
399&lt;li&gt;Each task essentially becomes its own shell instance.&lt;/li&gt;
400&lt;/ul&gt;
401&lt;/li&gt;
402&lt;li&gt;Must work on Linux and macOS systems.&lt;/li&gt;
403&lt;li&gt;By default, running &lt;code&gt;erd&lt;/code&gt; list all the available tasks (when I use make, I
404usually put a disclaimer that you should check Makefile to see all available
405target).&lt;/li&gt;
406&lt;li&gt;Should support passing arguments when you run it from a shell.&lt;/li&gt;
407&lt;li&gt;Normal variable as the same as environmental variables. There is no
408distinction. Every variable is also essentially an environment variable and
409can be used by other programs.&lt;/li&gt;
410&lt;li&gt;State between tasks is not shared, and this makes this “pure” shell instances.&lt;/li&gt;
411&lt;li&gt;Should be single-threaded for the start and later expanded with &lt;code&gt;@spawn&lt;/code&gt;
412command.&lt;/li&gt;
413&lt;li&gt;Variables behave like macros and are preprocessed before evaluation.&lt;/li&gt;
414&lt;li&gt;Should support something like &lt;code&gt;assure&lt;/code&gt; that would check if programs like C
415compiler or Python (whatever the project requires) are installed on a machine.&lt;/li&gt;
416&lt;/ul&gt;
417&lt;p&gt;Quite a reasonable list of requirements. I do this things already in my
418Makefiles or/and Bash scripts. But I would like to avoid repeating myself every
419time I start working on something new.&lt;/p&gt;
420&lt;p&gt;So I started with the following syntax.&lt;/p&gt;
421&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@env on
422&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
423&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# Override the default shell.&lt;/span&gt;
424&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@shell &lt;span style=&#34;color:#a31515&#34;&gt;/bin/&lt;/span&gt;bash
425&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
426&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# Assure that program is installed.&lt;/span&gt;
427&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@assure docker-compose pip python3
428&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
429&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# Load local dotenv files (these are then globally available).&lt;/span&gt;
430&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@dotenv .env
431&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@dotenv .env.sample
432&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@dotenv some_other_file
433&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
434&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# This are local variables but still accessible in tasks.&lt;/span&gt;
435&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@var HI = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;hey&amp;#34;&lt;/span&gt;
436&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@var TOKEN = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;sometoken&amp;#34;&lt;/span&gt;
437&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@var EMAIL = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;m@m.com&amp;#34;&lt;/span&gt;
438&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@var PASSWORD = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;pass&amp;#34;&lt;/span&gt;
439&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@var EDITOR = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;vim&amp;#34;&lt;/span&gt;
440&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
441&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@task dev &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Test chars .:&amp;#39;}{]!//&amp;#34;&lt;/span&gt; does
442&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; echo &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;...&amp;#34;&lt;/span&gt; $HI
443&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;end&lt;/span&gt;
444&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
445&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@task clean &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Cleans the obj files&amp;#34;&lt;/span&gt; does
446&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; rm .obj
447&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;end&lt;/span&gt;
448&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
449&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@task greet &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Greets the user&amp;#34;&lt;/span&gt; does
450&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; echo &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Hi user $TOKEN or $WINDOWID $EMAIL&amp;#34;&lt;/span&gt;
451&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;end&lt;/span&gt;
452&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
453&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@task stack &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Starts Docker stack&amp;#34;&lt;/span&gt; does
454&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; docker-compose -f stack.yml up
455&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;end&lt;/span&gt;
456&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
457&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@task todo &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Shows all todos in source files and count them&amp;#34;&lt;/span&gt; does
458&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; grep -ir &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;TODO|FIXME&amp;#34;&lt;/span&gt; . | wc -l
459&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;end&lt;/span&gt;
460&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
461&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@task test1 &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;For testing 1&amp;#34;&lt;/span&gt; does
462&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; unknown-command
463&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; echo &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;test1&amp;#34;&lt;/span&gt;
464&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; ls -lha
465&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;end&lt;/span&gt;
466&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
467&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@task test2 &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;For testing 2&amp;#34;&lt;/span&gt; does
468&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; echo &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;test1&amp;#34;&lt;/span&gt;
469&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; ls -lha
470&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; docker-compose -f samples/stack.yml up
471&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;end&lt;/span&gt;
472&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;One thing that I really like about Errand. Yes, this is what it is called. And
473it is available at &lt;a href=&#34;https://git.mitjafelicijan.com/errand.git/about/&#34;&gt;https://git.mitjafelicijan.com/errand.git/about/&lt;/a&gt;. Moving
474on. One thing that I really like is that a task is a persistent shell. By that I
475mean, that the whole task, even if it contains multiple command in one shell.
476In make each line in a target is that and you need to combine lines or add &lt;code&gt;\&lt;/code&gt;
477at the end of the line.&lt;/p&gt;
478&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# How you do this things in make.&lt;/span&gt;
479&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;target:
480&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; source .venv/bin/activate &lt;span style=&#34;color:#a31515&#34;&gt;\
481&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; python script.py
482&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;This solves this problem. Consider each task and what is being executed in that
483task a shell that will only close when all the tasks are completed.&lt;/p&gt;
484&lt;p&gt;By self-documenting I mean that if you are in a directory with &lt;code&gt;Errandfile&lt;/code&gt; in,
485if you only type &lt;code&gt;erd&lt;/code&gt; and press enter it should by default display all the
486possible targets. In make i was doing this by having a first target be something
487like &lt;code&gt;default&lt;/code&gt; that echos the message “Check Makefile for all available target.”
488Because all of the tasks in Errand require a message I use that to display let’s
489call it table of contents.&lt;/p&gt;
490&lt;p&gt;Because I don’t use any external dependencies this whole thing can be statically
491compiled. So that also checked one of the boxes.&lt;/p&gt;
492&lt;p&gt;It works on Linux and on a Mac so that’s also a bonus. I don’t believe this
493would work on Windows machines because of the way that I use shell instances. By
494you could use something like Windows Subsystem for Linux and run it in
495there. That is a valid option.&lt;/p&gt;
496&lt;p&gt;To finish this essay off, how was it to use it in “real life”. I have to be
497honest. Some of the missing features still bother me. &lt;code&gt;@dotenv&lt;/code&gt; directive is
498still missing and I need to implement this ASAP.&lt;/p&gt;
499&lt;p&gt;Another thing that needs to happen is support for streaming output. Currently
500commands like &lt;code&gt;docker-compose&lt;/code&gt; that runs in foreground mode is not compatible
501with Errand. So commands that stream output are an issue. I need to revisit how
502I initiate shell and how I read stdout and stderr. But that shouldn’t be a
503problem.&lt;/p&gt;
504&lt;p&gt;I have been very satisfied with this thing. I am pleasantly surprised by how
505useful it is. I really wanted to test this in the wild before I commit to it. I
506have more abandoned project than Google and it’s bringing a massive shame to my
507family at this point. So I wanted to be sure that this is even useful. And it
508actually is. Quite surprised at myself.&lt;/p&gt;
509&lt;p&gt;I really need to package this now and write proper docs. And maybe rewrite
510tokeniser. Its atrocious right now. Site to behold! But that is an issue for
511another time.&lt;/p&gt;
512</content:encoded>
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537 <item>
538 <title>I think I was completely wrong about Git workflows</title>
539 <link>https://mitjafelicijan.com/i-was-wrong-about-git-workflows.html</link>
540 <pubDate>Tue, 23 May 2023 12:00:00 &#43;0200</pubDate>
541 <guid>https://mitjafelicijan.com/i-was-wrong-about-git-workflows.html</guid>
542 <description>I have been using some approximation of GitFlow for years now and never reallyquestioned it to be honest.</description>
543 <content:encoded>&lt;p&gt;I have been using some approximation of &lt;a href=&#34;https://jeffkreeftmeijer.com/git-flow/&#34;&gt;Git
544Flow&lt;/a&gt; for years now and never really
545questioned it to be honest. When I create a repo I create develop branch and set
546it as default one and then merge to master from there. Seems reasonable enough.&lt;/p&gt;
547&lt;p&gt;One thing that I have learned is that long living branches are the devil. They
548always end up making a huge mess when they need to be merged eventually into
549master. So by that reason, what is the develop branch if not the longest living
550feature branch. And from my personal experience there was never a situation
551where I wasn’t sweating bullets when I had to merge develop back to master.&lt;/p&gt;
552&lt;p&gt;This realisation started to give me pause. So why the hell am I doing this, and
553is there a better way. Well the solution was always there. And it comes in a
554form of &lt;a href=&#34;https://git-scm.com/book/en/v2/Git-Basics-Tagging&#34;&gt;git tags&lt;/a&gt;.&lt;/p&gt;
555&lt;p&gt;So what are git tags? Git tags are references to specific points in a Git
556repository&#39;s history. They are used to mark important milestones, such as
557releases or significant commits, making it easier to identify and access
558specific versions of a project.&lt;/p&gt;
559&lt;p&gt;Somehow we have all hijacked the meaning of the master branch that it has to be
560the most releasable version of code. And this is also where the confusing about
561versioning the software kicks in. Because master branch implicitly says that we
562are dealing with the rolling release type of a software. And by having a develop
563branch we are hacking around this confusion. With a separation of develop and
564master we lock functionalities into place and forcing a stable vs development
565version of the software.&lt;/p&gt;
566&lt;p&gt;But if that is true and the long living branches are the devil then why have
567develop at all. I think that most of this comes to how continuous integration is
568being done. There usually is no granular access to tags and CD software deploys
569what is present on a specific branch, may that be master for production and
570develop for staging. This is a gross simplification and by having this in place
571we have completely removed tagging as a viable option to create a fix point in
572software cycle that says, this is the production ready code.&lt;/p&gt;
573&lt;p&gt;One cool thing about tags are that you can checkout a specific tag. So they
574behave very similarly as branches in that regard. And you don’t have the
575overhead of having two mainstream branches.&lt;/p&gt;
576&lt;p&gt;So what is the solution? One approach is to use development workflow, where all
577changes are made on the smaller branches and continuously merged into
578master. Where the software is ready to be pushed to production you tag the
579master branch. This approach eliminates the need for long-lived branches and
580simplifies the development process. It also encourages developers to make small,
581incremental changes that can be tested and deployed quickly. However, this
582approach may not be suitable for all projects or teams that heavily rely on
583automated deployment based on branch names only.&lt;/p&gt;
584&lt;p&gt;This also requires that developers always keep production in mind. No more
585living on an island of the develop branch. All your actions and code need to be
586ready to meet production standards on a much smaller timescale.&lt;/p&gt;
587&lt;p&gt;I think that we have complicated the workflow in an honest attempt to make
588things more streamlined but in the process of doing this, we have inadvertently
589made our lives much more complicated.&lt;/p&gt;
590&lt;p&gt;In conclusion, it&#39;s important to re-evaluate our workflows from time to time to
591see if they still make sense and if there are better alternatives available.
592Long-living branches can be problematic, and using tags to mark important
593milestones can simplify the development process.&lt;/p&gt;
594</content:encoded>
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607 <item>
608 <title>Rekindling my love for programming and enjoying the act of creating</title>
609 <link>https://mitjafelicijan.com/rekindling-my-love-for-programming.html</link>
610 <pubDate>Tue, 16 May 2023 12:00:00 &#43;0200</pubDate>
611 <guid>https://mitjafelicijan.com/rekindling-my-love-for-programming.html</guid>
612 <description>Programming can be a challenging and rewarding experience, but sometimes it&amp;#39;seasy to feel burnt out or disinterested.</description>
613 <content:encoded>&lt;p&gt;Programming can be a challenging and rewarding experience, but sometimes it&#39;s
614easy to feel burnt out or disinterested. I have lost the passion for coding over
615the past couple of months and it looked like I will never enjoy the coding as
616much as I did.&lt;/p&gt;
617&lt;p&gt;I was feeling burnt out with programming. I thought taking a break from it and
618focusing on other activities that I enjoy might be helpful. This way, I could
619come back to programming with a fresh perspective and renewed energy. I also
620thought about learning a new programming language or technology to keep things
621interesting and challenging.&lt;/p&gt;
622&lt;p&gt;However, what I didn&#39;t realize was that learning a new language or technology
623wasn&#39;t going to solve the underlying issue. I needed to take a step back and
624re-evaluate why I had lost my passion for programming in the first place. This
625involved taking a deep look into what I was doing that resulted in this rut.&lt;/p&gt;
626&lt;p&gt;Sometimes, it&#39;s easy to get caught up in the hype of new technologies or
627languages, and we can feel like we&#39;re missing out if we&#39;re not constantly
628learning and experimenting. However, it&#39;s important to remember that the latest
629and greatest isn&#39;t always the best fit for our projects or our
630interests. Instead of constantly chasing the next big thing, it can be helpful
631to focus on what truly interests us and what we&#39;re passionate about. This can
632help us stay motivated and engaged with our work, rather than feeling like we&#39;re
633just going through the motions.&lt;/p&gt;
634&lt;p&gt;I expressed that I had lost my passion for coding over the past couple of
635months, and I realized that the reason behind it was my tendency to spread
636myself too thin and not focus on completing interesting projects. In order to
637regain my passion for coding, I need to focus on projects that truly interest me
638and give me a sense of purpose and motivation.&lt;/p&gt;
639&lt;p&gt;Recently, I have been playing World of Warcraft more frequently and have become
640interested in developing addons for the game.&lt;/p&gt;
641&lt;p&gt;This quickly resulted in me creating three addons that improve the quality of
642life, and I subsequently developed a more useful add-on that encapsulates all
643the others I made.&lt;/p&gt;
644&lt;p&gt;I found it interesting that this action sparked a new interest in me.
645Additionally, I discovered the Lua language, which reminded me that coding
646should be fun rather than just a struggle with a language. It should be pure,
647unadulterated fun.&lt;/p&gt;
648&lt;p&gt;I wasn&#39;t fighting the syntax, nor was I focused on finding the most optimal
649solution. I simply created things without the pressure of making them the best
650they could possibly be.&lt;/p&gt;
651&lt;p&gt;This made me realize that I actually adore simple languages that get out of the
652way and let you express what you want to do. It forced me to rethink a lot about
653what I use and what I actually enjoy.&lt;/p&gt;
654&lt;p&gt;I have decided to stick to the basics. For a scripting language, I will use
655Lua. For networking, I will use Golang. And for any special needs, I will rely
656on C. I do not require Rust, Nim, or Zig. This selection is more than sufficient
657for my needs. I have to stay true to this simplicity. There is something to the
658Occam&#39;s Razor.&lt;/p&gt;
659&lt;p&gt;I&#39;ve been struggling with a lack of creativity lately, but now I&#39;m experiencing
660a real change. I realized I needed to take a step back and stop actively trying
661to address the issue. I needed to stop worrying and overthinking it. I simply
662needed some time. Looking back, I don&#39;t think I&#39;ve taken any significant time
663off in the last 10 years.&lt;/p&gt;
664&lt;p&gt;Suddenly, I find myself with the energy and passion to complete multiple small
665projects. It doesn&#39;t feel like a chore at all. Who knew I needed WoW to
666kickstart everything. Inspiration really does come from the strangest places.&lt;/p&gt;
667</content:encoded>
668 </item>
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696 <item>
697 <title>Trying to build a New kind of terminal emulator for the modern age</title>
698 <link>https://mitjafelicijan.com/trying-to-build-a-new-kind-of-terminal-emulator.html</link>
699 <pubDate>Thu, 26 Jan 2023 12:00:00 &#43;0200</pubDate>
700 <guid>https://mitjafelicijan.com/trying-to-build-a-new-kind-of-terminal-emulator.html</guid>
701 <description>Over the past few weeks, I have been really thinking about terminal emulators,how we interact with computers, the separation of text-based programs and GUIones.</description>
702 <content:encoded>&lt;p&gt;Over the past few weeks, I have been really thinking about terminal emulators,
703how we interact with computers, the separation of text-based programs and GUI
704ones. To be perfectly honest, I got pissed off one evening when I was cleaning
705up files on my computer. Normally, I go into console and do &lt;code&gt;ncdu&lt;/code&gt; and check
706where the junk is. Then I start deleting stuff. Without any discrimination,
707usually. But when it comes to screenshots, I have learned that it&#39;s good to keep
708them somewhere near if I need to refer to something that I was doing. I am an
709avid screenshot taker. So at that point I checked Pictures folder and also did a
710basic search &lt;code&gt;find . -type f -name &amp;quot;*.jpg&amp;quot;&lt;/code&gt; for all the JPEG files in my home
711directory and immediately got pissed off. Why can’t I see thumbnails in my
712terminal? I know why, but why in the year of 2022 this is still a problem. I am
713used to traversing my disk via terminal. I am faster, and I am more comfortable
714this way. But when it comes to visualization, I then need to revert to GUI
715applications and again find the same file to see it. I know that programs like
716&lt;code&gt;feh&lt;/code&gt; and &lt;code&gt;sxiv&lt;/code&gt; are available, but I would just like to see the preview. Like
717&lt;a href=&#34;https://jupyter.org/&#34;&gt;Jupyter notebook&lt;/a&gt; or something similar. Just having it
718inline. Part of a result.&lt;/p&gt;
719&lt;p&gt;It also didn’t help that I was spending some time with the &lt;a href=&#34;https://plan9.io/plan9/&#34;&gt;Plan
7209&lt;/a&gt; Operating system. More specifically
721&lt;a href=&#34;http://9front.org/&#34;&gt;9FRONT&lt;/a&gt;. The way that &lt;a href=&#34;http://acme.cat-v.org/&#34;&gt;ACME editor&lt;/a&gt;
722handles text editing is just wonderful. Different and fresh somehow, even though
723it’s super old.&lt;/p&gt;
724&lt;p&gt;So, I went on a lookout for an interesting way of visualizing results of some
725query. I found these applications to be outstanding examples of how not to be a
726captive of a predetermined way of doing things.&lt;/p&gt;
727&lt;ul&gt;
728&lt;li&gt;&lt;a href=&#34;https://www.wolfram.com/mathematica/&#34;&gt;Wolfram Mathematica&lt;/a&gt;&lt;/li&gt;
729&lt;li&gt;&lt;a href=&#34;https://jupyter.org/&#34;&gt;Jupyter notebooks&lt;/a&gt;&lt;/li&gt;
730&lt;li&gt;&lt;a href=&#34;http://www.9front.org&#34;&gt;Plan 9 / 9FRONT&lt;/a&gt;&lt;/li&gt;
731&lt;li&gt;&lt;a href=&#34;https://templeos.org/&#34;&gt;Temple OS&lt;/a&gt;&lt;/li&gt;
732&lt;li&gt;&lt;a href=&#34;https://www.gnu.org/software/emacs/&#34;&gt;Emacs&lt;/a&gt;&lt;/li&gt;
733&lt;/ul&gt;
734&lt;p&gt;My idea is not as out there as ACME is, but it is a spin on the terminal
735emulators. I like the modes that Vi/Vim provides you with. I like the way the
736Emacs does its own &lt;code&gt;M-x&lt;/code&gt; &lt;code&gt;M-c&lt;/code&gt;. Furthermore, I really like how Mathematica and
737Jupyter present the data in a free flowing form. And I love how Temple OS is
738basically a C interpreter on some level.&lt;/p&gt;
739&lt;blockquote&gt;
740&lt;p&gt;&lt;strong&gt;Note:&lt;/strong&gt; This is part 1 of the journey. Nowhere finished yet. I am just
741tinkering with this at the moment. This whole thing can easily spectacularly
742fail.&lt;/p&gt;
743&lt;/blockquote&gt;
744&lt;p&gt;So I started. I knew that I wanted to have the couple of modes, but I didn’t
745like the repetition of keystrokes, so the only option was to have some sort of
746toggle and indicate to the user that they are in a special mode. Like Vi does
747for Normal and Visual mode.&lt;/p&gt;
748&lt;p&gt;These modes would for the first version be:&lt;/p&gt;
749&lt;ul&gt;
750&lt;li&gt;&lt;em&gt;Preview mode&lt;/em&gt; (toggle with Ctrl &#43; P)
751&lt;ul&gt;
752&lt;li&gt;When this mode would be enabled, the &lt;code&gt;ls&lt;/code&gt; command would try to find images
753from the results and display thumbnails from them in the terminal itself.
754No ASCII art. Proper images. In a grid!&lt;/li&gt;
755&lt;/ul&gt;
756&lt;/li&gt;
757&lt;li&gt;&lt;em&gt;Detach mode&lt;/em&gt; (toggle with Ctrl &#43; D)
758&lt;ul&gt;
759&lt;li&gt;When this mode would be enabled, every command would open a new window
760and execute that command in it. This would be useful for starting &lt;code&gt;htop&lt;/code&gt;
761in a separate window.&lt;/li&gt;
762&lt;/ul&gt;
763&lt;/li&gt;
764&lt;/ul&gt;
765&lt;p&gt;The reason for having these modes togglable is to not ask for previews every
766time. You enable a mode and until you disable it, it behaves that way. Purely
767out of ergonomic reasons.&lt;/p&gt;
768&lt;p&gt;I would like to treat every terminal I open as a session mentally. When I start
769using the terminal, I start digging deeper into the issue I am trying to
770resolve. And while I am doing this, I would like to open detached windows
771etc. A lot of these things can be done easily with something like
772&lt;a href=&#34;https://i3wm.org/&#34;&gt;i3&lt;/a&gt;, but also that pull you out of the context of what you
773were doing. I would like to orchestrate everything from one single point.&lt;/p&gt;
774&lt;p&gt;In planning for this project, I knew that I would need to use a language like C
775and a library such as &lt;a href=&#34;https://www.libsdl.org/&#34;&gt;SDL2&lt;/a&gt; in order to achieve the
776desired results. I had considered other options, but ultimately determined that
777&lt;a href=&#34;https://www.libsdl.org/&#34;&gt;SDL2&lt;/a&gt; was the best fit based on its capabilities and
778reputation in the programming community.&lt;/p&gt;
779&lt;p&gt;At first, I thought the idea of a hardware accelerated terminal was a bit of a
780joke. It seemed like such a niche and unnecessary feature, especially given the
781fact that terminal emulators have been around for decades and have always relied
782on software rendering. But to be fair, &lt;a href=&#34;https://alacritty.org/&#34;&gt;Alacritty&lt;/a&gt; is
783doing the same thing. Well, they are doing a remarkable job at it.&lt;/p&gt;
784&lt;p&gt;So, I embarked on a journey. Everything has to start somewhere. For me, it
785started with creating a window! It has to start somewhere. 🙂&lt;/p&gt;
786&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// Oh, Hi Mark!
787&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// Create the window, obviously.
788&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;SDL_Window *window = SDL_CreateWindow(
789&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; WINDOW_TITLE, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
790&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; WINDOW_WIDTH, WINDOW_HEIGHT,
791&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; SDL_WINDOW_RESIZABLE | SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);
792&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;I continued like this to get some text displayed on the screen.&lt;/p&gt;
793&lt;p&gt;I noted that
794&lt;a href=&#34;https://wiki.libsdl.org/SDL_ttf/TTF_RenderText_Solid&#34;&gt;&lt;code&gt;TTF_RenderText_Solid&lt;/code&gt;&lt;/a&gt;
795rendered text really poorly. There were no antialiasing at all. In my wisdom, I
796never checked the documentation. Well, that was a fail. To uneducated like me:
797&lt;code&gt;TTF_RenderText_Solid&lt;/code&gt; renders Latin1 text at fast quality to a new 8-bit
798surface. So, that&#39;s why the texts looked like shit. No wonder.&lt;/p&gt;
799&lt;p&gt;Remarks on &lt;code&gt;TTF_RenderText_Solid&lt;/code&gt;: This function will allocate a new 8-bit,
800palettized surface. The surface&#39;s 0 pixel will be the colorkey, giving a
801transparent background. The 1 pixel will be set to the text color.&lt;/p&gt;
802&lt;p&gt;After I replaced it with
803&lt;a href=&#34;https://wiki.libsdl.org/SDL_ttf/TTF_RenderText_LCD&#34;&gt;&lt;code&gt;TTF_RenderText_LCD&lt;/code&gt;&lt;/a&gt; which
804renders Latin1 text at LCD subpixel quality to a new ARGB surface, the text
805started looking good. Really make sure you read the documentation. It’s actually
806good. As a side note, you can find all the documentation regarding &lt;a href=&#34;https://wiki.libsdl.org/&#34;&gt;SDL2 on
807their Wiki&lt;/a&gt;.&lt;/p&gt;
808&lt;p&gt;After that was done, I started working on displaying other things like &lt;code&gt;Preview&lt;/code&gt;
809and &lt;code&gt;Detach&lt;/code&gt; modes. This wasn’t really that hard. In SDL2 you can check all the
810available events with &lt;code&gt;while (SDL_PollEvent(&amp;amp;event) &amp;gt; 0)&lt;/code&gt; and have a bunch of
811switch statements to determine which key is currently being pressed. More about
812keys, &lt;a href=&#34;https://documentation.help/SDL/sdlkey.html&#34;&gt;SDLKey&lt;/a&gt; and mroe about
813pooling the events on
814&lt;a href=&#34;https://documentation.help/SDL/sdlpollevent.html&#34;&gt;SDL_PollEvent&lt;/a&gt;.&lt;/p&gt;
815&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;while&lt;/span&gt; (SDL_PollEvent(&amp;amp;event) &amp;gt; 0)
816&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;{
817&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;switch&lt;/span&gt; (event.type)
818&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; {
819&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;case&lt;/span&gt; SDL_QUIT:
820&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; running = false;
821&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;break&lt;/span&gt;;
822&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
823&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;case&lt;/span&gt; SDL_TEXTINPUT:
824&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; (!meta_key_pressed)
825&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; {
826&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; strncat(input_prompt_text, event.text.text, 1);
827&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; update_input_prompt = true;
828&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
829&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;break&lt;/span&gt;;
830&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
831&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
832&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;After that was somewhat working correctly, I started creating a struct that
833would hold all the commands and results and I call them Cells. Yes, I stole that
834naming idea from Jupyter.&lt;/p&gt;
835&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;typedef&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;struct&lt;/span&gt;
836&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;{
837&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#2b91af&#34;&gt;char&lt;/span&gt; *command;
838&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#2b91af&#34;&gt;char&lt;/span&gt; *result;
839&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; SDL_Surface *surface;
840&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; SDL_Texture *texture;
841&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; SDL_Rect rect;
842&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;} Cell;
843&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;I am at a place now where I am starting to implement scrolling. This will for
844sure be fun to code. Memory management in C is super easy. 😂&lt;/p&gt;
845&lt;p&gt;I have also added a simple &lt;a href=&#34;https://en.wikipedia.org/wiki/INI_file&#34;&gt;INI file like
846configuration&lt;/a&gt; support. It is done in an
847&lt;a href=&#34;https://github.com/nothings/stb/blob/master/docs/stb_howto.txt&#34;&gt;STB style of
848header&lt;/a&gt; and maps
849to specific options supported by the terminal. It is not universal, and the code
850below demonstrates how I will use it in the future.&lt;/p&gt;
851&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;#ifndef CONFIG_H
852&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;#define CONFIG_H
853&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;&lt;/span&gt;
854&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;/*
855&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# This is a comment
856&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;
857&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# This is the first configuration option
858&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;dettach=value11111
859&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;
860&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# This is the second configuration option
861&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;preview=value22222
862&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;
863&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# This is the third configuration option
864&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;debug=value33333
865&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;*/&lt;/span&gt;
866&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
867&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// Define a struct to hold the configuration options
868&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;typedef&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;struct&lt;/span&gt;
869&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;{
870&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#2b91af&#34;&gt;char&lt;/span&gt; dettach[256];
871&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#2b91af&#34;&gt;char&lt;/span&gt; preview[256];
872&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#2b91af&#34;&gt;char&lt;/span&gt; debug[256];
873&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;} Config;
874&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
875&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// Read the configuration file and return the options as a struct
876&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;extern&lt;/span&gt; Config read_config_file(&lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; &lt;span style=&#34;color:#2b91af&#34;&gt;char&lt;/span&gt; *filename)
877&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;{
878&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// Create a struct to hold the configuration options
879&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; Config config = {0};
880&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
881&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// Open the configuration file
882&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; FILE *file = fopen(filename, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;r&amp;#34;&lt;/span&gt;);
883&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
884&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// Read each line from the file
885&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; &lt;span style=&#34;color:#2b91af&#34;&gt;char&lt;/span&gt; line[256];
886&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;while&lt;/span&gt; (fgets(line, &lt;span style=&#34;color:#00f&#34;&gt;sizeof&lt;/span&gt;(line), file))
887&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; {
888&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// Check if this line is a comment or empty
889&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; (line[0] == &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;#&amp;#39;&lt;/span&gt; || line[0] == &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;\n&amp;#39;&lt;/span&gt;)
890&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;continue&lt;/span&gt;;
891&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
892&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// Parse the line to get the option and value
893&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; &lt;span style=&#34;color:#2b91af&#34;&gt;char&lt;/span&gt; option[128], value[128];
894&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; (sscanf(line, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;%[^=]=%s&amp;#34;&lt;/span&gt;, option, value) != 2)
895&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;continue&lt;/span&gt;;
896&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
897&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// Set the value of the appropriate option in the config struct
898&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; (strcmp(option, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;dettach&amp;#34;&lt;/span&gt;) == 0)
899&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; {
900&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; strncpy(config.option1, value, &lt;span style=&#34;color:#00f&#34;&gt;sizeof&lt;/span&gt;(config.option1));
901&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
902&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;else&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; (strcmp(option, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;preview&amp;#34;&lt;/span&gt;) == 0)
903&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; {
904&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; strncpy(config.option2, value, &lt;span style=&#34;color:#00f&#34;&gt;sizeof&lt;/span&gt;(config.option2));
905&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
906&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;else&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; (strcmp(option, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;debug&amp;#34;&lt;/span&gt;) == 0)
907&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; {
908&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; strncpy(config.option3, value, &lt;span style=&#34;color:#00f&#34;&gt;sizeof&lt;/span&gt;(config.option3));
909&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
910&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
911&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
912&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// Close the configuration file
913&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; fclose(file);
914&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
915&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// Return the configuration options
916&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt; config;
917&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
918&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
919&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;#endif
920&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;This is as far as I managed to get for now. I have a daily job and this
921prohibits me to work on these things full time. But I should probably get back
922and finish this. At least have a simple version working out, so I can start
923testing it on my machines. Fingers crossed. 🕵️‍♂️&lt;/p&gt;
924</content:encoded>
925 </item>
926
927
928
929 <item>
930 <title>Microsoundtrack — That sound that machine makes when struggling</title>
931 <link>https://mitjafelicijan.com/that-sound-that-machine-makes-when-struggling.html</link>
932 <pubDate>Sun, 16 Oct 2022 12:00:00 &#43;0200</pubDate>
933 <guid>https://mitjafelicijan.com/that-sound-that-machine-makes-when-struggling.html</guid>
934 <description>A couple of months ago, I got an idea about micro soundtracks.</description>
935 <content:encoded>&lt;p&gt;A couple of months ago, I got an idea about micro soundtracks. In this concept,
936you are the observer, director, and audience in this tiny movies.&lt;/p&gt;
937&lt;p&gt;What you do is to attempt to imagine what would be happening around you based on
938a title of the song and let the song help you fill the void in your story.&lt;/p&gt;
939&lt;p&gt;I made these songs is Logic Pro X. Every year or so I do this kind of thing and
940make a couple of songs similar to this. But this is the first time I am posting
941about it.&lt;/p&gt;
942&lt;p&gt;You can listen to the whole set on
943&lt;a href=&#34;https://www.youtube.com/watch?v=_5oXBhSmF3c&#34;&gt;Youtube&lt;/a&gt; or scroll down the page
944and there are embedded players for each song.&lt;/p&gt;
945&lt;h2 id=&#34;a-bunch-of-inter-dimensional-people-with-loud-clocks&#34;&gt;A bunch of inter-dimensional people with loud clocks&lt;/h2&gt;
946&lt;p&gt;A group of inter-dimensional people are going up and down the elevator with you
947while having loud clocks around their necks. Each clock ticks on a different
948frequency. A lot of other sounds are getting drawn into your dimension,
949resulting in a strange merging of dimensions.&lt;/p&gt;
950&lt;iframe style=&#34;border: 0; width: 100%; height: 42px;&#34; src=&#34;https://bandcamp.com/EmbeddedPlayer/album=3913808801/size=small/bgcol=ffffff/linkcol=0687f5/track=1349272965/transparent=true/&#34; seamless title=&#34;Bandcamp&#34;&gt;&lt;a href=&#34;https://mitjafelicijan.bandcamp.com/album/that-sound-that-machine-makes-when-struggling&#34;&gt;That sound that machine makes when struggling by Mitja Felicijan&lt;/a&gt;&lt;/iframe&gt;
951&lt;h2 id=&#34;two-black-holes-conversing-about-the-weather&#34;&gt;Two black holes conversing about the weather&lt;/h2&gt;
952&lt;p&gt;You are a traveler in a spaceship flying very close to two colliding black holes
953having a discussion about the weather while tearing each other apart. During all
954this your ship is getting pulled into the event horizon of both black holes,
955putting a lot of strain on your spaceship.&lt;/p&gt;
956&lt;iframe style=&#34;border: 0; width: 100%; height: 42px;&#34; src=&#34;https://bandcamp.com/EmbeddedPlayer/album=3913808801/size=small/bgcol=ffffff/linkcol=0687f5/track=1756714200/transparent=true/&#34; seamless title=&#34;Bandcamp&#34;&gt;&lt;a href=&#34;https://mitjafelicijan.bandcamp.com/album/that-sound-that-machine-makes-when-struggling&#34;&gt;That sound that machine makes when struggling by Mitja Felicijan&lt;/a&gt;&lt;/iframe&gt;
957&lt;h2 id=&#34;a-planet-where-every-organism-is-a-plant&#34;&gt;A planet where every organism is a plant&lt;/h2&gt;
958&lt;p&gt;You land on a planet where every living organism is a plant and among those
959plants some of them are highly intelligent, and you were asked to make first
960contact with the native species. Your visit takes place in a giant cave where
961you are meeting these plants, and they are talking to you.&lt;/p&gt;
962&lt;iframe style=&#34;border: 0; width: 100%; height: 42px;&#34; src=&#34;https://bandcamp.com/EmbeddedPlayer/album=3913808801/size=small/bgcol=ffffff/linkcol=0687f5/track=3710973979/transparent=true/&#34; seamless title=&#34;Bandcamp&#34;&gt;&lt;a href=&#34;https://mitjafelicijan.bandcamp.com/album/that-sound-that-machine-makes-when-struggling&#34;&gt;That sound that machine makes when struggling by Mitja Felicijan&lt;/a&gt;&lt;/iframe&gt;
963&lt;h2 id=&#34;bio-implants-having-a-fit-and-reprogramming-your-brain&#34;&gt;Bio implants having a fit and reprogramming your brain&lt;/h2&gt;
964&lt;p&gt;In a distant future where everybody has bio implants, you have just received
965your first one, which happens to be a brain implant. Something goes wrong, and
966your implant is starting to misbehave, and you are experiencing brain
967malfunctions. You are on the streets at night a couple of hours after your
968procedure. You can feel your sanity breaking down.&lt;/p&gt;
969&lt;iframe style=&#34;border: 0; width: 100%; height: 42px;&#34; src=&#34;https://bandcamp.com/EmbeddedPlayer/album=3913808801/size=small/bgcol=ffffff/linkcol=0687f5/track=1157430581/transparent=true/&#34; seamless title=&#34;Bandcamp&#34;&gt;&lt;a href=&#34;https://mitjafelicijan.bandcamp.com/album/that-sound-that-machine-makes-when-struggling&#34;&gt;That sound that machine makes when struggling by Mitja Felicijan&lt;/a&gt;&lt;/iframe&gt;
970&lt;h2 id=&#34;cow-animation&#34;&gt;Cow animation&lt;/h2&gt;
971&lt;p&gt;I also made this little cow animation. Go into full screen to see the effects in
972more details.&lt;/p&gt;
973&lt;p&gt;&lt;video src=&#34;/posts/microsoundtrack/cow.m4v&#34; controls loop&gt;&lt;/video&gt;&lt;/p&gt;
974</content:encoded>
975 </item>
976
977
978
979 <item>
980 <title>State of Web Technologies and Web development in year 2022</title>
981 <link>https://mitjafelicijan.com/state-of-web-technologies-and-web-development-in-year-2022.html</link>
982 <pubDate>Thu, 06 Oct 2022 12:00:00 &#43;0200</pubDate>
983 <guid>https://mitjafelicijan.com/state-of-web-technologies-and-web-development-in-year-2022.html</guid>
984 <description>Initial thoughtsThis post is a critique on the current state of web development.</description>
985 <content:encoded>&lt;h2 id=&#34;initial-thoughts&#34;&gt;Initial thoughts&lt;/h2&gt;
986&lt;p&gt;&lt;em&gt;This post is a critique on the current state of web development. It is an
987opinionated post! I will learn more about this in the future, and probably
988slightly change my mind about some of the things I criticize.&lt;/em&gt;&lt;/p&gt;
989&lt;p&gt;I have started working on a hobby project about two weeks ago, and I wanted to
990use that situation as a learning one. Trying new things, new technologies, new
991tools. I always considered myself to be an adventurous person when it comes to
992technology. I never shy away from trying new languages, new operating systems
993etc. Likewise, I find the whole experience satisfying, and it tickles that part
994of my brain that finds discovery the highest of the mountains to climb.&lt;/p&gt;
995&lt;p&gt;What I always wanted to make was a coding game, that you would play in a browser
996(just to eliminate building binaries for each operating system) where you would
997level up your character and go into these scriptable battles. You know, RPG
998elements.&lt;/p&gt;
999&lt;p&gt;So, the natural way to go would be some sort of SPA (single page application)
1000with basic routing and some state management. Nothing crazy.&lt;/p&gt;
1001&lt;blockquote&gt;
1002&lt;p&gt;&lt;strong&gt;Before we move on&lt;/strong&gt;, I have to be transparent. Take my views on this with
1003a grain of salt. I have only scratched the surface with these technologies,
1004and my knowledge is full of gaps. This is my experience using some of these
1005products for the first time or in a limited capacity.&lt;/p&gt;
1006&lt;/blockquote&gt;
1007&lt;p&gt;Having this out of the way, I got myself a fresh pot of coffee and down the
1008rabbit hole I went.&lt;/p&gt;
1009&lt;h2 id=&#34;giving-react-js-a-spin&#34;&gt;Giving React JS a spin&lt;/h2&gt;
1010&lt;p&gt;I first tried &lt;a href=&#34;https://reactjs.org/&#34;&gt;React JS&lt;/a&gt;. I kind of like it. Furthermore,
1011I have worked with libraries like this in the past and also wrote a couple of
1012them (nothing compared to that level), but I had the basic understanding of what
1013was going on. I rolled up a project quickly and had basic things done in a
1014matter of two hours, which was impressive.&lt;/p&gt;
1015&lt;p&gt;I prefer using &lt;a href=&#34;https://tailwindcss.com/&#34;&gt;Tailwind CSS&lt;/a&gt; for my styling
1016pleasures, and integrating that was also a painless experience. It was actually
1017nice to see that some things got better with time. In about 2 minutes I got
1018Tailwind working, and I was able to use classes at my disposal. All that
1019&lt;code&gt;postcss&lt;/code&gt; stuff was taken care of by adding a couple of things in config files
1020(all described really well in their documentation).&lt;/p&gt;
1021&lt;p&gt;It is not that different from Vue which I have had more encounters with in the
1022past People will probably call me a lunatic for saying this. But you know, it is
1023the truth. Same same, but different. I still believe that using libraries like
1024this is beneficial. I am not a JavaScript purist. They all have their quirks,
1025but at the end of the day, I truly believe it’s worth it.&lt;/p&gt;
1026&lt;h2 id=&#34;bundlers-and-transpilers&#34;&gt;Bundlers and Transpilers&lt;/h2&gt;
1027&lt;p&gt;I still reject calling &lt;a href=&#34;https://www.typescriptlang.org/&#34;&gt;Typescript&lt;/a&gt; to
1028&lt;a href=&#34;https://www.javascript.com/&#34;&gt;JavaScript&lt;/a&gt; conversion a &amp;quot;compilation process&amp;quot;. I
1029call them &lt;a href=&#34;https://devopedia.org/transpiler&#34;&gt;transpilers&lt;/a&gt;, and I don’t care! 😈&lt;/p&gt;
1030&lt;p&gt;The first one that I ever used was &lt;a href=&#34;https://webpack.js.org/&#34;&gt;webpack&lt;/a&gt;, and it
1031was an absolute horrific experience. Saying this, it is an absolutely fantastic
1032tool. I felt more like a config editor than actually a programmer. To be fair,
1033I am a huge fan of &lt;a href=&#34;https://www.gnu.org/software/make/&#34;&gt;make&lt;/a&gt;, and you can do as
1034you wish with this information. I like my build systems simple.&lt;/p&gt;
1035&lt;p&gt;Also, isn’t it interesting that we need something like
1036&lt;a href=&#34;https://babeljs.io/&#34;&gt;Babel&lt;/a&gt; to make JavaScript code work in a browser that has
1037only one client side scripting available, which is by no accident also
1038JavaScript. Why? I know why it’s needed, but seriously, why.&lt;/p&gt;
1039&lt;p&gt;I haven’t used Babel for years now. Or if I did, it was packaged together by
1040some other bundler thingy. Which does not make things better, but at least I
1041didn’t need to worry about it.&lt;/p&gt;
1042&lt;p&gt;I really don’t like complicated build systems. I really don’t like abstracting
1043code and making things appear magical. The older I get, the more I appreciate
1044clear and clean, expressive code. No one-liners, if possible.&lt;/p&gt;
1045&lt;p&gt;But I have to give props to &lt;a href=&#34;https://vitejs.dev/&#34;&gt;Vite&lt;/a&gt;! This was one of the
1046best developer experiences I have ever had. Granted, it still has magical
1047properties. And yes, it still is a bundler and abstracts things to the nth
1048degree. But at least it didn’t force me to configure 700 lines of JSON. And I
1049know that this makes me a hypocrite. You can’t have it all. Nonetheless, my
1050reasoning here is, if using bundlers is inevitable, then at least they should
1051provide an excellent developer experience.&lt;/p&gt;
1052&lt;p&gt;I also noticed that now the catch-all phrase is “blazingly fast” and “lightning
1053fast” and “next generation” and stuff like that. I mean, yeah, tools should get
1054faster with time. But saying that starting a project now takes 2 seconds instead
1055of 20 seconds is something that is a break it or make it kind of a deal is
1056ridiculous. I don’t mind waiting a couple of seconds every couple of days. I
1057also don’t create 700 projects every day, and also who does? This argument has
1058no bite. All I want is a decent reload time (~100ms is more than good enough for
1059me) and that is it.&lt;/p&gt;
1060&lt;p&gt;You don’t need to sell me benefits if I only get them when I start a fresh
1061project, and then try to convince me that this is somehow changing the fate of
1062the universe. First of all, it is not. And second, if this is your only argument
1063for your tool, I would advise you to maybe re-focus your efforts to something
1064else. Vite says that startup times are really fast. And if that would be the
1065only thing differentiating it from other tools, I would ignore it. But it has
1066some really compelling features like &lt;a href=&#34;https://www.geeksforgeeks.org/reactjs-hot-module-replacement/&#34;&gt;Hot Module
1067Replacement&lt;/a&gt; that
1068really works well. It was a joy to use.&lt;/p&gt;
1069&lt;p&gt;So, I will be definitely using Vite in the future.&lt;/p&gt;
1070&lt;h2 id=&#34;jam-stack-mach-stack-no-snack&#34;&gt;Jam Stack, Mach Stack no snack&lt;/h2&gt;
1071&lt;p&gt;Let&#39;s get a couple of the acronyms out of the way, so we all know what we are
1072talking about:&lt;/p&gt;
1073&lt;ul&gt;
1074&lt;li&gt;Jam Stack - JavaScript, API and Markup&lt;/li&gt;
1075&lt;li&gt;Mach Stack - Microservices, API-first, Cloud-Native SaaS, Headless&lt;/li&gt;
1076&lt;/ul&gt;
1077&lt;p&gt;It is so hard to follow all these new trendy things happening around you, that
1078it makes you have a massive &lt;strong&gt;FOMO&lt;/strong&gt; all the time. But on the other hand, you
1079also don’t want to be that old fart that doesn’t move with the times and still
1080writes his trusty jQuery code while listening to Blink 182 All the small things
1081on full blast. It’s a good song, don’t get me wrong, but there are other songs
1082out there.&lt;/p&gt;
1083&lt;p&gt;I have to admit. &lt;a href=&#34;https://vercel.com/&#34;&gt;Vercel&lt;/a&gt; is really cool! Love the
1084simplicity of the service. You could compare it to
1085&lt;a href=&#34;https://www.netlify.com/&#34;&gt;Netlify&lt;/a&gt;. I haven’t tried Netlify extensively, but
1086from a couple of experimental deployments I still prefer Vercel. It is much more
1087streamlined, but maybe this is bias in me. I really like Vercel’s Analytics,
1088which give you a &lt;a href=&#34;https://web.dev/vitals/&#34;&gt;Core Web Vitals report&lt;/a&gt; in their
1089admin console. Kind of cool, I’m not going to lie.&lt;/p&gt;
1090&lt;p&gt;This whole idea about frontend and backend merging into &lt;a href=&#34;https://www.debugbear.com/blog/server-side-rendering&#34;&gt;SSR (server-side
1091rendering)&lt;/a&gt; looks so good
1092on paper. It almost doesn’t come with any major flaws.&lt;/p&gt;
1093&lt;p&gt;But when it comes to the actual implementation, there is much to be desired.
1094I’m going to lump &lt;a href=&#34;https://nextjs.org/&#34;&gt;Next.js&lt;/a&gt; and
1095&lt;a href=&#34;https://nuxtjs.org/&#34;&gt;Nuxt.js&lt;/a&gt; together because they are essentially the same
1096thing, just a different library.&lt;/p&gt;
1097&lt;p&gt;Now comes the reality. Mixing backend and frontend in this manner creates this
1098weird mental model where you kind of rely on magical properties of these
1099libraries. You relinquish control over to them for better developer experience.
1100But is that really true? Initially, I was so stoked about it. However, the more
1101I used them, the more I felt uncomfortable. I felt dirty, actually. Maybe this
1102is because I come from old ways of doing things where you control every step of
1103request, and allowing something to hijack it feels like blasphemy.&lt;/p&gt;
1104&lt;p&gt;More than that, some pretty significant technical issues arose from this. How do
1105you do JWT token authentication? You put it in &lt;code&gt;api&lt;/code&gt; folder and then do some
1106fetching and storing into local state management. But doing this also requires
1107some tinkering with await/async stuff on the React/Vue side of things. And then
1108you need to write middleware for it. And the more I look at it, the more I see
1109that this whole thing was not meant to be used like this, and it all feels and
1110looks like a huge hack.&lt;/p&gt;
1111&lt;p&gt;The issue I have with this is that they over-promise and under-deliver. They
1112want to be an all-in-one replacement for everything, and they don’t deliver on
1113this promise. And how could they?! We have to be fair. It is an impossible task.&lt;/p&gt;
1114&lt;p&gt;They sell you &lt;a href=&#34;https://www.geeksforgeeks.org/overview-of-noops/&#34;&gt;NoOps&lt;/a&gt;, but
1115when you need to accomplish something a little bit more out of the scope of
1116Hello World, you have to make hacky decisions to make it work. And having a
1117deployment strategy that relies on many moving parts is never a good idea.
1118Abstracting too much is usually a sign of bad architecture.&lt;/p&gt;
1119&lt;p&gt;Lately, this has become a huge trend that will for sure bite us in the future.
1120And let’s not get it twisted. By doing this, PaaS providers like
1121&lt;a href=&#34;https://aws.amazon.com/&#34;&gt;AWS&lt;/a&gt;, &lt;a href=&#34;https://cloud.google.com/&#34;&gt;GCS&lt;/a&gt;, etc. obscure
1122their billing, and you end up paying more than you really should. And even if
1123that is not an issue, it comes down to the principle of things. AWS is known for
1124having multiple “currencies“ inside their projects like write operations, read
1125operations, etc. which add up, and it creates this impossible to track billing
1126scheme. It all behaves suspiciously like a pay-to-win game you could find on
1127mobile phones that scams you out of your money.&lt;/p&gt;
1128&lt;p&gt;And as far as I am concerned, the most important thing was me not coding the
1129functionalities for the game I want to make. I was battling libraries and cloud
1130providers. How to deploy, what settings are relevant. Bad documentation or
1131multiple versions of achieving the same thing. You are getting bombarded by all
1132this information, and you don’t really have any control over it.
1133Production-ready code becomes a joke, essentially. Especially if you tend to
1134work on that project for a prolonged period of time.&lt;/p&gt;
1135&lt;p&gt;All of these options end up creating a fatigue. What to choose, what not to
1136choose. Unnecessary worrying about if the stack will still be deemed worthy in
1137six months. There is elegance in simplicity.&lt;/p&gt;
1138&lt;blockquote&gt;
1139&lt;p&gt;JavaScript UI frameworks and libraries work in cycles. Every six months or
1140so, a new one pops up, claiming that it has revolutionized UI development.
1141Thousands of developers adopt it into their new projects, blog posts are
1142written, Stack Overflow questions are asked and answered, and then a newer
1143(and even more revolutionary) framework pops up to usurp the throne.
1144— Ian Allen&lt;/p&gt;
1145&lt;/blockquote&gt;
1146&lt;p&gt;And this jab at these libraries and cloud providers is not done out of malice.
1147It is a real concern that I have about them. In my life, I have seen
1148technologies come and go, but the basics always stick around. So surrendering
1149all the power you have to a library or a cloud provider is in my opinion a
1150stupid move.&lt;/p&gt;
1151&lt;h2 id=&#34;tailwind-css-still-rocks&#34;&gt;Tailwind CSS still rocks!&lt;/h2&gt;
1152&lt;p&gt;You know, many people say negative things about Tailwind. And after a lot of
1153deliberation, I came to the conclusion that Tailwind is good for two types of
1154developers. Tailwind is good for a complete noob or a senior developer. A
1155complete noob doesn’t really care about inner workings of CSS, and a senior
1156developer also doesn’t care about CSS. Well, at least, not anymore. And
1157developers in between usually have the biggest issues with it. Not always of
1158course, but in a lot of cases.&lt;/p&gt;
1159&lt;p&gt;I like the creature comforts of Tailwind. Being utility first would make me
1160argue that it is actually more similar to &lt;a href=&#34;https://sass-lang.com/&#34;&gt;Sass&lt;/a&gt; or
1161&lt;a href=&#34;https://lesscss.org/&#34;&gt;Less&lt;/a&gt; than something like Bootstrap. Not technically, but
1162ideologically. After I started using it, I never looked back. I use it every
1163time I need to do something web related.&lt;/p&gt;
1164&lt;p&gt;Writing CSS for general things feels like going several steps back. Instead of
1165focusing on what you are actually trying to achieve, you focus on notations like
1166&lt;a href=&#34;https://en.bem.info/methodology/css/&#34;&gt;BEM&lt;/a&gt;, code structuring, optimizing HTML
1167size. Just doing things that make 0.1% difference. You know that saying: Early
1168optimization is the root of all evil. Exactly that.&lt;/p&gt;
1169&lt;p&gt;I am also not saying that Tailwind is the cure for everything. Sometimes custom
1170CSS is necessary. But from what I found out in using it for almost two years in
1171a production environment (on a site getting quite a lot of traffic and
1172constantly being changed), I can say without any reservations that Tailwind
1173saved our asses countless times. We would be rewriting CSS all the time without
1174it. And I don’t really think writing CSS is the best way to spend my time.&lt;/p&gt;
1175&lt;p&gt;I have also noticed that people who criticize Tailwind the most never actually
1176used it in a real project that has a long lifetime with plenty of changes that
1177will happen in the future.&lt;/p&gt;
1178&lt;p&gt;But you know, whatever floats your boat!&lt;/p&gt;
1179&lt;h2 id=&#34;code-maintainability&#34;&gt;Code maintainability&lt;/h2&gt;
1180&lt;p&gt;Somehow, people also stopped talking about maintenance. If you constantly try to
1181catch the latest and greatest train, you are by that logic always trying new
1182things. Which is a good thing if you want to learn about technologies and try
1183them. But for the production environment, you have to have a stable stack that
1184doesn’t change every 6 months.&lt;/p&gt;
1185&lt;p&gt;You can lock dependencies for sure. Nevertheless, the hype train moves along
1186anyway. And the mindset this breeds goes against locking the code. This
1187bleeding-edge rolling release cycle is not helping. That is why enterprise
1188solutions usually look down on these popular stacks and only do bare minimum to
1189appear hip and cool.&lt;/p&gt;
1190&lt;p&gt;With that said, I still think that progress is good, but should be taken with a
1191grain of salt. If your project is something that should be built once and then
1192rarely updated, going with the latest stack is a possible way to go. But, if you
1193are working on a project that lasts for years, you should probably approach it
1194with some level of caution. Web development is often times too volatile.&lt;/p&gt;
1195&lt;h2 id=&#34;web-development-has-a-marketing-issue&#34;&gt;Web development has a marketing issue&lt;/h2&gt;
1196&lt;p&gt;I noticed that almost every project now has this marketing spin put on it.
1197Everything is blazingly fast now. I get it, they are competing for your
1198attention, but what happened to just being truthful and not inflating reality.&lt;/p&gt;
1199&lt;p&gt;And in order to appeal to mass market, they leave things out of their marketing
1200materials. These open-source projects are now behaving more and more like
1201companies do. Which is a scary thought on its self.&lt;/p&gt;
1202&lt;p&gt;And we are also seeing a rise in a concept of building a company in the open,
1203which is a good thing, don&#39;t get me wrong. But when it is using open-source to
1204lure people and then lock them in their ecosystem, there is where I have issues
1205with it.&lt;/p&gt;
1206&lt;p&gt;This might be because I have been using GNU/Linux for 20 years now and have been
1207so beholden for my success to open-source that I see issues when open-source is
1208being used to trick people into a false sense of security that these projects
1209are built in the spirit of open-source. Because there is a difference. They are
1210NOT! They have a really specific goal in mind. And the open-source is being used
1211as a delivery system. Which is in my opinion disgusting!&lt;/p&gt;
1212&lt;h2 id=&#34;conclusion&#34;&gt;Conclusion&lt;/h2&gt;
1213&lt;p&gt;I will end my post with this. Web development is running now in circles. People
1214are discovering &lt;a href=&#34;https://www.tutorialspoint.com/remote-procedure-call-rpc&#34;&gt;RPC&lt;/a&gt;
1215now and this is the now the next big thing. &lt;a href=&#34;https://graphql.org/&#34;&gt;GraphQL&lt;/a&gt; is
1216so passé. And I am so tired of it all. Of blazingly fast libraries, of all these
1217new technologies that are actually just a remake of old ones. Of just the
1218general spirit of the web. I will just use what I already know. Which worked 10
1219years ago and will work 10 years after this. I will adopt a couple of little
1220tools like Vite. But I will not waste my time on this anymore.&lt;/p&gt;
1221&lt;p&gt;It was a good exercise to get in touch with what’s new now. Nothing really
1222changed that much. FOMO is now cured! Now I have to get my ass back to actually
1223code and make the project that I wanted to make in the first place.&lt;/p&gt;
1224</content:encoded>
1225 </item>
1226
1227
1228
1229
1230
1231
1232
1233 <item>
1234 <title>Aerial photography of algae spotted on river Sava</title>
1235 <link>https://mitjafelicijan.com/aerial-photography-of-algae-spotted-on-river-sava.html</link>
1236 <pubDate>Sat, 13 Aug 2022 12:00:00 &#43;0200</pubDate>
1237 <guid>https://mitjafelicijan.com/aerial-photography-of-algae-spotted-on-river-sava.html</guid>
1238 <description>This is a bit of a different post than I usually write, but quite interestingone to me.</description>
1239 <content:encoded>&lt;p&gt;This is a bit of a different post than I usually write, but quite interesting
1240one to me. River Sava has plenty of hydropower plants located down the stream.
1241This makes regulating the strength of a current easier than normally. Because of
1242lower stream strength and high temperatures, algae has formed on the river.
1243This is the first time I&#39;ve seen something like this in my whole life.&lt;/p&gt;
1244&lt;p&gt;Below are some photographs taken from a DJI drone capturing the event.&lt;/p&gt;
1245&lt;figure&gt;
1246&lt;img src=&#34;/posts/algae-sava/dji-algae-0.jpg&#34; alt=&#34;Algae on Sava&#34; /&gt;
1247&lt;/figure&gt;
1248&lt;figure&gt;
1249&lt;img src=&#34;/posts/algae-sava/dji-algae-1.jpg&#34; alt=&#34;Algae on Sava&#34; /&gt;
1250&lt;/figure&gt;
1251&lt;figure&gt;
1252&lt;img src=&#34;/posts/algae-sava/dji-algae-2.jpg&#34; alt=&#34;Algae on Sava&#34; /&gt;
1253&lt;/figure&gt;
1254&lt;figure&gt;
1255&lt;img src=&#34;/posts/algae-sava/dji-algae-3.jpg&#34; alt=&#34;Algae on Sava&#34; /&gt;
1256&lt;/figure&gt;
1257&lt;figure&gt;
1258&lt;img src=&#34;/posts/algae-sava/dji-algae-4.jpg&#34; alt=&#34;Algae on Sava&#34; /&gt;
1259&lt;/figure&gt;
1260&lt;figure&gt;
1261&lt;img src=&#34;/posts/algae-sava/dji-algae-5.jpg&#34; alt=&#34;Algae on Sava&#34; /&gt;
1262&lt;/figure&gt;
1263&lt;p&gt;I will try to get more photos of this in the future days and if something
1264intriguing shows up will post it again on the blog.&lt;/p&gt;
1265</content:encoded>
1266 </item>
1267
1268
1269
1270 <item>
1271 <title>What would DNA sound if synthesized to an audio file</title>
1272 <link>https://mitjafelicijan.com/what-would-dna-sound-if-synthesized.html</link>
1273 <pubDate>Tue, 05 Jul 2022 12:00:00 &#43;0200</pubDate>
1274 <guid>https://mitjafelicijan.com/what-would-dna-sound-if-synthesized.html</guid>
1275 <description>IntroductionLately, I have been thinking a lot about the nature of life, what are thefoundation blocks of life and things like that.</description>
1276 <content:encoded>&lt;h2 id=&#34;introduction&#34;&gt;Introduction&lt;/h2&gt;
1277&lt;p&gt;Lately, I have been thinking a lot about the nature of life, what are the
1278foundation blocks of life and things like that. It&#39;s remarkable how complex and
1279on the other hand simple the creation is when you look at it. The miracle of
1280life keeps us grounded when our imagination goes wild. If the DNA are the blocks
1281of life, you could consider them to be an API nature provided us to better
1282understand all of this chaos masquerading as order.&lt;/p&gt;
1283&lt;p&gt;I have been reading a lot about superintelligence and our somehow misguided path
1284to create general artificial intelligence. What would the building blocks or our
1285creation look like? Is the compression really the ultimate storage of
1286information? Will our creation also ponder this questions when creating new
1287worlds for themselves, or will we just disappear into the vastness of
1288possibilities? It is a little offensive that we are playing God whilst being
1289completely ignorant of our own reality. Who knows! Like many other
1290breakthroughs, this one will also come at a cost not known to us when it finally
1291happens.&lt;/p&gt;
1292&lt;p&gt;To keep things a bit lighter, I decided to convert some popular DNA sequences
1293into an audio files for us to listen to. I am not the first one, nor I will be
1294the last one to do this. But it is an interesting exercise in better
1295understanding the relationship between art and science. Maybe listening to DNA
1296instead of parsing it will find a way into better understanding, or at least
1297enjoying the creation and cryptic nature of life.&lt;/p&gt;
1298&lt;h2 id=&#34;dna-encoding-and-primer-example&#34;&gt;DNA encoding and primer example&lt;/h2&gt;
1299&lt;p&gt;I have been exploring DNA in the past in my post from about 3 years ago in
1300&lt;a href=&#34;/encoding-binary-data-into-dna-sequence.html&#34;&gt;Encoding binary data into DNA
1301sequence&lt;/a&gt; where I have been
1302converting all sorts of data into DNA sequences.&lt;/p&gt;
1303&lt;p&gt;This will be a similar exercise but instead of converting to DNA, I will be
1304generating tones from Nucleotides.&lt;/p&gt;
1305&lt;table&gt;
1306&lt;thead&gt;
1307&lt;tr&gt;
1308&lt;th&gt;Nucleotides&lt;/th&gt;
1309&lt;th&gt;Note&lt;/th&gt;
1310&lt;th&gt;Frequency&lt;/th&gt;
1311&lt;/tr&gt;
1312&lt;/thead&gt;
1313&lt;tbody&gt;
1314&lt;tr&gt;
1315&lt;td&gt;&lt;strong&gt;A&lt;/strong&gt; (Adenine)&lt;/td&gt;
1316&lt;td&gt;A&lt;/td&gt;
1317&lt;td&gt;440 Hz&lt;/td&gt;
1318&lt;/tr&gt;
1319&lt;tr&gt;
1320&lt;td&gt;&lt;strong&gt;C&lt;/strong&gt; (Cytosine)&lt;/td&gt;
1321&lt;td&gt;C&lt;/td&gt;
1322&lt;td&gt;783.99 Hz&lt;/td&gt;
1323&lt;/tr&gt;
1324&lt;tr&gt;
1325&lt;td&gt;&lt;strong&gt;G&lt;/strong&gt; (Guanine)&lt;/td&gt;
1326&lt;td&gt;G&lt;/td&gt;
1327&lt;td&gt;523.25 Hz&lt;/td&gt;
1328&lt;/tr&gt;
1329&lt;tr&gt;
1330&lt;td&gt;&lt;strong&gt;T&lt;/strong&gt; (Thymine)&lt;/td&gt;
1331&lt;td&gt;D&lt;/td&gt;
1332&lt;td&gt;587.33 Hz&lt;/td&gt;
1333&lt;/tr&gt;
1334&lt;/tbody&gt;
1335&lt;/table&gt;
1336&lt;p&gt;Since we do not have T in equal-tempered scale, I choose D to represent T note.&lt;/p&gt;
1337&lt;p&gt;You can check &lt;a href=&#34;https://pages.mtu.edu/~suits/notefreqs.html&#34;&gt;Frequencies for equal-tempered scale, A4 = 440
1338Hz&lt;/a&gt;. For this tuning, we also
1339choose &lt;code&gt;Speed of Sound = 345 m/s = 1130 ft/s = 770 miles/hr&lt;/code&gt;.&lt;/p&gt;
1340&lt;p&gt;Now that we have this out of the way, we can also brush up on the DNA sequencing
1341a bit. This is a famous quote I also used for the encoding tests, and it goes
1342like this.&lt;/p&gt;
1343&lt;blockquote&gt;
1344&lt;p&gt;How wonderful that we have met with a paradox. Now we have some hope of
1345making progress.
1346― Niels Bohr&lt;/p&gt;
1347&lt;/blockquote&gt;
1348&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;gt;SEQ1
1349&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;GACAGCTTGTGTACAAGTGTGCTTGCTCGCGAGCGGGTACGCGCGTGGGCTAACAAGTGA
1350&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;GCCAGCAGGTGAACAAGTGTGCGGACAAGCCAGCAGGTGCGCGGACAAGCTGGCGGGTGA
1351&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ACAAGTGTGCCGGTGAGCCAACAAGCAGACAAGTAAGCAGGTACGCAGGCGAGCTTGTCA
1352&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ACTCACAAGATCGCTTGTGTACAAGTGTGCGGACAAGCCAGCAGGTGCGCGGACAAGTAT
1353&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;GCTTGCTGGCGGACAAGCCAGCTTGTAAGCGGACAAGCTTGCGCACAAGCTGGCAGGCCT
1354&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;GCCGGCTCGCGTACAAATTCACAAGTAAGTACGCTTGCGTGTACGCGGGTATGTATACTC
1355&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;AACCTCACCAAACGGGACAAGATCGCCGGCGGGCTAGTATACAAGAACGCTTGCCAGTAC
1356&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;AACC
1357&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;This is what we gonna work with to get things rolling forward, when creating
1358parser and waveform generator.&lt;/p&gt;
1359&lt;h2 id=&#34;parsing-dna-data&#34;&gt;Parsing DNA data&lt;/h2&gt;
1360&lt;p&gt;This step is rather simple one. All we need to do is parse input DNA sequence in
1361&lt;a href=&#34;https://en.wikipedia.org/wiki/FASTA_format&#34;&gt;FASTA format&lt;/a&gt; well known in
1362&lt;a href=&#34;https://en.wikipedia.org/wiki/Bioinformatics&#34;&gt;Bioinformatics&lt;/a&gt; to extract single
1363Nucleotides that will be converted into separate tones based on equal-tempered
1364scale explained above.&lt;/p&gt;
1365&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;nucleotide_tone_map = {
1366&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;A&amp;#39;&lt;/span&gt;: 440,
1367&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;C&amp;#39;&lt;/span&gt;: 523.25,
1368&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;G&amp;#39;&lt;/span&gt;: 783.99,
1369&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;T&amp;#39;&lt;/span&gt;: 587.33, &lt;span style=&#34;color:#008000&#34;&gt;# converted to D&lt;/span&gt;
1370&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
1371&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1372&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;def&lt;/span&gt; split(word):
1373&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt; [char &lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; char &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; word]
1374&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1375&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;def&lt;/span&gt; generate_from_dna_sequence(sequence):
1376&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; nucleotide &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; split(sequence):
1377&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; print(nucleotide, nucleotide_tone_map[nucleotide])
1378&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;generating-sine-wave&#34;&gt;Generating sine wave&lt;/h2&gt;
1379&lt;p&gt;Because we are essentially creating a long stream of notes we will be appending
1380sine notes to a global array we will later use for creating a WAV file out of
1381it.&lt;/p&gt;
1382&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; math
1383&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1384&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;def&lt;/span&gt; append_sinewave(freq=440.0, duration_milliseconds=500, volume=1.0):
1385&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;global&lt;/span&gt; audio
1386&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1387&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; num_samples = duration_milliseconds * (sample_rate / 1000.0)
1388&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1389&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; x &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; range(int(num_samples)):
1390&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; audio.append(volume * math.sin(2 * math.pi * freq * (x / sample_rate)))
1391&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1392&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt;
1393&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;The sine wave generated here is the standard beep. If you want something more
1394aggressive, you could try a square or saw tooth waveform.&lt;/p&gt;
1395&lt;h2 id=&#34;generating-a-wav-file-from-accumulated-sine-waves&#34;&gt;Generating a WAV file from accumulated sine waves&lt;/h2&gt;
1396&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; wave
1397&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; struct
1398&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1399&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;def&lt;/span&gt; save_wav(file_name):
1400&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; wav_file = wave.open(file_name, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;w&amp;#39;&lt;/span&gt;)
1401&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; nchannels = 1
1402&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; sampwidth = 2
1403&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1404&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; nframes = len(audio)
1405&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; comptype = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;NONE&amp;#39;&lt;/span&gt;
1406&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; compname = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;not compressed&amp;#39;&lt;/span&gt;
1407&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; wav_file.setparams((nchannels, sampwidth, sample_rate, nframes, comptype, compname))
1408&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1409&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; sample &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; audio:
1410&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; wav_file.writeframes(struct.pack(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;h&amp;#39;&lt;/span&gt;, int(sample * 32767.0)))
1411&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1412&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; wav_file.close()
1413&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;44100 is the industry standard sample rate - CD quality. If you need to save on
1414file size, you can adjust it downwards. The standard for low quality is, 8000 or
14158kHz.&lt;/p&gt;
1416&lt;p&gt;WAV files here are using short, 16 bit, signed integers for the sample size.
1417So, we multiply the floating-point data we have by 32767, the maximum value for
1418a short integer.&lt;/p&gt;
1419&lt;blockquote&gt;
1420&lt;p&gt;It is theoretically possible to use the floating point -1.0 to 1.0 data
1421directly in a WAV file, but not obvious how to do that using the wave module
1422in Python.&lt;/p&gt;
1423&lt;/blockquote&gt;
1424&lt;h2 id=&#34;generating-spectograms&#34;&gt;Generating Spectograms&lt;/h2&gt;
1425&lt;p&gt;I have tried two methods of doing this and both were just fine. I however opted
1426out to use the &lt;a href=&#34;https://linux.die.net/man/1/sox&#34;&gt;SoX - Sound eXchange, the Swiss Army knife of audio
1427manipulation&lt;/a&gt; one because it didn&#39;t require
1428anything else.&lt;/p&gt;
1429&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sox output.wav -n spectrogram -o spectrogram.png
1430&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;An example spectrogram of Ludwig van Beethoven Symphony No. 6 First movement.&lt;/p&gt;
1431&lt;audio controls&gt;
1432 &lt;source src=&#34;/posts/dna-synthesized/symphony-no6-1st-movement.mp3&#34; type=&#34;audio/mpeg&#34;&gt;
1433&lt;/audio&gt;
1434&lt;figure&gt;
1435&lt;img src=&#34;/posts/dna-synthesized/symphony-no6-1st-movement.png&#34; alt=&#34;Ludwig van Beethoven Symphony No. 6 First movement&#34; /&gt;
1436&lt;/figure&gt;
1437&lt;p&gt;The other option could also be in combination with
1438&lt;a href=&#34;http://www.gnuplot.info/&#34;&gt;gnuplot&lt;/a&gt;. This would require an intermediary step,
1439however.&lt;/p&gt;
1440&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sox output.wav audio.dat
1441&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;tail -n&#43;3 audio.dat &amp;gt; audio_only.dat
1442&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;gnuplot audio.gpi
1443&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;And input file &lt;code&gt;audio.gpi&lt;/code&gt; that would be passed to gnuplot looks something like
1444this.&lt;/p&gt;
1445&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;# set output format and size
1446&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;set term png size 1000,280
1447&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1448&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;# set output file
1449&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;set output &amp;#34;audio.png&amp;#34;
1450&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1451&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;# set y range
1452&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;set yr [-1:1]
1453&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1454&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;# we want just the data
1455&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;unset key
1456&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;unset tics
1457&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;unset border
1458&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;set lmargin 0
1459&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;set rmargin 0
1460&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;set tmargin 0
1461&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;set bmargin 0
1462&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1463&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;# draw rectangle to change background color
1464&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;set obj 1 rectangle behind from screen 0,0 to screen 1,1
1465&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;set obj 1 fillstyle solid 1.0 fillcolor rgbcolor &amp;#34;#ffffff&amp;#34;
1466&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1467&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;# draw data with foreground color
1468&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;plot &amp;#34;audio_only.dat&amp;#34; with lines lt rgb &amp;#39;red&amp;#39;
1469&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;pre-generated-sequences&#34;&gt;Pre-generated sequences&lt;/h2&gt;
1470&lt;p&gt;What I did was take interesting parts from an animal&#39;s genome and feed it to a
1471tone generator script. This then generated a WAV file and I converted those to
1472MP3, so they can be played in a browser. The last step was creating a
1473spectrogram based on a WAV file.&lt;/p&gt;
1474&lt;h3 id=&#34;niels-bohr-quote&#34;&gt;Niels Bohr quote&lt;/h3&gt;
1475&lt;audio controls&gt;
1476 &lt;source src=&#34;/posts/dna-synthesized/quote/out.mp3&#34; type=&#34;audio/mpeg&#34;&gt;
1477&lt;/audio&gt;
1478&lt;figure&gt;
1479&lt;img src=&#34;/posts/dna-synthesized/quote/spectogram.png&#34; alt=&#34;Spectogram&#34; /&gt;
1480&lt;/figure&gt;
1481&lt;h3 id=&#34;mouse&#34;&gt;Mouse&lt;/h3&gt;
1482&lt;p&gt;This is part of a mouse genome &lt;code&gt;Mus_musculus.GRCm39.dna.nonchromosomal&lt;/code&gt;. You
1483can get &lt;a href=&#34;http://ftp.ensembl.org/pub/release-106/fasta/mus_musculus/dna/&#34;&gt;genom data
1484here&lt;/a&gt;.&lt;/p&gt;
1485&lt;audio controls&gt;
1486 &lt;source src=&#34;/posts/dna-synthesized/mouse/out.mp3&#34; type=&#34;audio/mpeg&#34;&gt;
1487&lt;/audio&gt;
1488&lt;figure&gt;
1489&lt;img src=&#34;/posts/dna-synthesized/mouse/spectogram.png&#34; alt=&#34;Spectogram&#34; /&gt;
1490&lt;/figure&gt;
1491&lt;h3 id=&#34;bison&#34;&gt;Bison&lt;/h3&gt;
1492&lt;p&gt;This is part of a bison genome &lt;code&gt;Bison_bison_bison.Bison_UMD1.0.cdna&lt;/code&gt;. You can
1493get &lt;a href=&#34;http://ftp.ensembl.org/pub/release-106/fasta/bison_bison_bison/cdna/&#34;&gt;genom data
1494here&lt;/a&gt;.&lt;/p&gt;
1495&lt;audio controls&gt;
1496 &lt;source src=&#34;/posts/dna-synthesized/bison/out.mp3&#34; type=&#34;audio/mpeg&#34;&gt;
1497&lt;/audio&gt;
1498&lt;figure&gt;
1499&lt;img src=&#34;/posts/dna-synthesized/bison/spectogram.png&#34; alt=&#34;Spectogram&#34; /&gt;
1500&lt;/figure&gt;
1501&lt;h3 id=&#34;taurus&#34;&gt;Taurus&lt;/h3&gt;
1502&lt;p&gt;This is part of a taurus genome &lt;code&gt;Bos_taurus.ARS-UCD1.2.cdna&lt;/code&gt;. You can get
1503&lt;a href=&#34;http://ftp.ensembl.org/pub/release-106/fasta/bos_taurus/cdna/&#34;&gt;genom data
1504here&lt;/a&gt;.&lt;/p&gt;
1505&lt;audio controls&gt;
1506 &lt;source src=&#34;/posts/dna-synthesized/taurus/out.mp3&#34; type=&#34;audio/mpeg&#34;&gt;
1507&lt;/audio&gt;
1508&lt;figure&gt;
1509&lt;img src=&#34;/posts/dna-synthesized/taurus/spectogram.png&#34; alt=&#34;Spectogram&#34; /&gt;
1510&lt;/figure&gt;
1511&lt;h2 id=&#34;making-a-drummer-out-of-a-dna-sequence&#34;&gt;Making a drummer out of a DNA sequence&lt;/h2&gt;
1512&lt;p&gt;To make things even more interesting, I decided to send this data via MIDI to my
1513&lt;a href=&#34;https://www.elektron.se/en/model-samples&#34;&gt;Elektron Model:Samples&lt;/a&gt;. This is a
1514really cool piece of equipment that supports MIDI in via USB and 3.5 mm audio
1515jack.&lt;/p&gt;
1516&lt;p&gt;Elektron is connected to my MacBook via USB cable and audio out is patched to a
1517Sony Bluetooth speaker I have that supports 3.5 mm audio in. Elektron doesn&#39;t
1518have internal speakers.&lt;/p&gt;
1519&lt;figure&gt;
1520&lt;img src=&#34;/posts/dna-synthesized/elektron/IMG_0619.jpg&#34; alt=&#34;&#34; /&gt;
1521&lt;/figure&gt;
1522&lt;figure&gt;
1523&lt;img src=&#34;/posts/dna-synthesized/elektron/IMG_0620.jpg&#34; alt=&#34;&#34; /&gt;
1524&lt;/figure&gt;
1525&lt;figure&gt;
1526&lt;img src=&#34;/posts/dna-synthesized/elektron/IMG_0622.jpg&#34; alt=&#34;&#34; /&gt;
1527&lt;/figure&gt;
1528&lt;p&gt;For communicating with Elektron, I choose &lt;code&gt;pygame&lt;/code&gt; Python module that has MIDI
1529built in. With this, it was rather simple to send notes to the device. All I did
1530was map MIDI notes to the actual Nucleotides.&lt;/p&gt;
1531&lt;p&gt;Before all of this I also checked Audio MIDI Setup app under MacOS and checked
1532MIDI Studio by pressing ⌘-2.&lt;/p&gt;
1533&lt;figure&gt;
1534&lt;img src=&#34;/posts/dna-synthesized/elektron/midi-studio.jpg&#34; alt=&#34;&#34; /&gt;
1535&lt;/figure&gt;
1536&lt;p&gt;The whole script that parses and send notes to the Elektron looks like this.&lt;/p&gt;
1537&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; pygame.midi
1538&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; time
1539&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1540&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;pygame.midi.init()
1541&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1542&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print(pygame.midi.get_default_output_id())
1543&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print(pygame.midi.get_device_info(0))
1544&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1545&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;player = pygame.midi.Output(1)
1546&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;player.set_instrument(2)
1547&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1548&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;def&lt;/span&gt; send_note(note, velocity):
1549&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;global&lt;/span&gt; player
1550&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; player.note_on(note, velocity)
1551&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; time.sleep(0.3)
1552&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; player.note_off(note, velocity)
1553&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1554&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1555&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;nucleotide_midi_map = {
1556&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;A&amp;#39;&lt;/span&gt;: 60,
1557&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;C&amp;#39;&lt;/span&gt;: 90,
1558&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;G&amp;#39;&lt;/span&gt;: 160,
1559&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;T&amp;#39;&lt;/span&gt;: 180, &lt;span style=&#34;color:#008000&#34;&gt;# is D&lt;/span&gt;
1560&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
1561&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1562&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;with&lt;/span&gt; open(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;quote.fa&amp;#34;&lt;/span&gt;) &lt;span style=&#34;color:#00f&#34;&gt;as&lt;/span&gt; f:
1563&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; sequence = f.read().replace(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\n&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;&amp;#39;&lt;/span&gt;)
1564&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1565&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; nucleotide &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; [char &lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; char &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; sequence]:
1566&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Playing nucleotide &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;{}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; with MIDI note &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;{}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt;.format(
1567&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; nucleotide, nucleotide_midi_map[nucleotide]))
1568&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; send_note(nucleotide_midi_map[nucleotide], 127)
1569&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1570&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;del&lt;/span&gt; player
1571&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;pygame.midi.quit()
1572&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;video src=&#34;/posts/dna-synthesized/elektron/elektron.mp4&#34; controls&gt;&lt;/video&gt;&lt;/p&gt;
1573&lt;p&gt;All of this could be made much more interesting if I choose different
1574instruments for different Nucleotides, or doing more funky stuff with Elektron.
1575But for now, this should be enough. It is just a proof of concept. Something to
1576play around with.&lt;/p&gt;
1577&lt;h2 id=&#34;going-even-further&#34;&gt;Going even further&lt;/h2&gt;
1578&lt;p&gt;As you probably notice, the end results are quite similar to each other. This is
1579to be expected because we are operating only with 4 notes essentially. What
1580could make this more interesting is using something like
1581&lt;a href=&#34;https://supercollider.github.io/&#34;&gt;Supercollider&lt;/a&gt; to create more interesting
1582sounds. By transposing notes or using effects based on repeated data in a
1583sequence. Possibilities are endless.&lt;/p&gt;
1584&lt;p&gt;It is really astonishing what can be achieved with a little bit of code and an
1585idea. I could see this becoming an interesting background soundscape instrument
1586if done properly. It could replace random note generator with something more
1587intriguing, biological, natural.&lt;/p&gt;
1588&lt;p&gt;I actually find the results fascinating. I took some time and listened to this
1589music of nature. Even though it&#39;s quite the same, it&#39;s also quite different.
1590The subtle differences on repeat kind of creates music on its own. Makes you
1591wonder. It kind of puts Occam’s Razor in its place. Nature for sure loves to
1592make things as energy efficient as possible.&lt;/p&gt;
1593</content:encoded>
1594 </item>
1595
1596
1597
1598 <item>
1599 <title>Trying out Helix code editor as my main editor</title>
1600 <link>https://mitjafelicijan.com/tying-out-helix-code-editor.html</link>
1601 <pubDate>Thu, 30 Jun 2022 12:00:00 &#43;0200</pubDate>
1602 <guid>https://mitjafelicijan.com/tying-out-helix-code-editor.html</guid>
1603 <description>I have been searching for a lightweight code editor for quite some time.</description>
1604 <content:encoded>&lt;p&gt;I have been searching for a lightweight code editor for quite some time. One of
1605the main reasons was that I wanted something that doesn&#39;t burn through CPU and
1606RAM usage is not through the roof. I have been mostly using Visual Studio Code.
1607It&#39;s been an outstanding editor. I have no quarrel with it at all. It&#39;s just
1608time to spice life up with something new.&lt;/p&gt;
1609&lt;p&gt;I have been on this search for a couple of years. I have tried Vim, Neovim,
1610Emacs, Doom Emacs, Micro and couple more. Among most of them, I liked Micro and
1611Doom Emacs the most. Micro editor was a little too basic for me. And Doom Emacs
1612was a bit too hardcore. This does not reflect on any of the editors. It&#39;s just
1613my personal preference.&lt;/p&gt;
1614&lt;blockquote&gt;
1615&lt;p&gt;I tried Helix Editor about a year ago. But I didn&#39;t pay attention to it.
1616Tried it and saw it&#39;s similar to Vi and just said no. I was premature to
1617dismiss it.&lt;/p&gt;
1618&lt;/blockquote&gt;
1619&lt;p&gt;One of the things I actually miss is line wrapping for certain files. When
1620writing Markdown, line wrapping would be very helpful. Editing such a document
1621is frustrating to say the least. Some of the Markdown to HTML converters don&#39;t
1622take kindly of new lines between sentences. Not paragraphs, sentences. And I use
1623Markdown to write this blog you are reading.&lt;/p&gt;
1624&lt;p&gt;But other than this, I have been extremely satisfied by it. It&#39;s been a pleasant
1625surprise. There have been zero issues with the editor.&lt;/p&gt;
1626&lt;p&gt;One thing to do before you are able to use autocompletion and make use Language
1627Server support is to install the language server with NPM.&lt;/p&gt;
1628&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;npm install -g typescript typescript-language-server
1629&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;I am still getting used to the keyboard shortcuts and getting better. What Helix
1630does really well is packing in sane defaults and even though because currently
1631there is no plugin support I haven&#39;t found any need for them. It has all that
1632you would need. It goes to extreme measures to show a user what is going on with
1633popups that show you what the keyboard shortcuts are.&lt;/p&gt;
1634&lt;p&gt;And it comes us packed with many
1635&lt;a href=&#34;https://github.com/helix-editor/helix/wiki/Themes&#34;&gt;really good themes&lt;/a&gt;.&lt;/p&gt;
1636&lt;figure&gt;
1637&lt;img src=&#34;/posts/helix-editor/editor.png&#34; alt=&#34;Editor&#34; /&gt;
1638&lt;/figure&gt;
1639&lt;p&gt;It&#39;s still young but has this mature feeling to it. It has sane defaults and
1640mimics Vim (works a bit differently, but the overall idea is similar).&lt;/p&gt;
1641</content:encoded>
1642 </item>
1643
1644
1645
1646 <item>
1647 <title>Wireless Application Protocol and the mobile web before the web</title>
1648 <link>https://mitjafelicijan.com/wap-mobile-web-before-the-web.html</link>
1649 <pubDate>Thu, 30 Dec 2021 12:00:00 &#43;0200</pubDate>
1650 <guid>https://mitjafelicijan.com/wap-mobile-web-before-the-web.html</guid>
1651 <description>A little stroll down the history laneAbout two weeks ago, I watched this outstanding documentary on YouTubeSpringboard: the secret history of the first realsmartphone about the history ofsmartphones and phones in general.</description>
1652 <content:encoded>&lt;h2 id=&#34;a-little-stroll-down-the-history-lane&#34;&gt;A little stroll down the history lane&lt;/h2&gt;
1653&lt;p&gt;About two weeks ago, I watched this outstanding documentary on YouTube
1654&lt;a href=&#34;https://www.youtube.com/watch?v=b9_Vh9h3Ohw&#34;&gt;Springboard: the secret history of the first real
1655smartphone&lt;/a&gt; about the history of
1656smartphones and phones in general. It brought back so many memories. I never had
1657an actual smartphone before the Android. The closest to smartphone was &lt;a href=&#34;https://www.gsmarena.com/sony_ericsson_p1-1982.php&#34;&gt;Sony
1658Ericsson P1&lt;/a&gt;. A fantastic
1659phone and I broke it in Prague after a party and that was one of those rare
1660occasions where I was actually mad at myself. But nevertheless, after that
1661phone, the next one was an Android one.&lt;/p&gt;
1662&lt;p&gt;Before that, I only owned normal phones from Nokia and Siemens etc. Nothing
1663special, actually. These are the phones we are talking about. Before 2007.
1664Apple and Android phones didn&#39;t exist yet.&lt;/p&gt;
1665&lt;p&gt;These phones were rocking:&lt;/p&gt;
1666&lt;ul&gt;
1667&lt;li&gt;No selfie cameras.&lt;/li&gt;
1668&lt;li&gt;~2 inch displays.&lt;/li&gt;
1669&lt;li&gt;~120 MHz beast CPU&#39;s.&lt;/li&gt;
1670&lt;li&gt;144p main cameras.&lt;/li&gt;
1671&lt;li&gt;But they had a headphone jack.&lt;/li&gt;
1672&lt;/ul&gt;
1673&lt;p&gt;Let&#39;s take a look at these beauties.&lt;/p&gt;
1674&lt;figure&gt;
1675&lt;img src=&#34;/posts/wap/phones.gif&#34; alt=&#34;Old phones&#34; /&gt;
1676&lt;/figure&gt;
1677&lt;h2 id=&#34;wap---wireless-application-protocol&#34;&gt;WAP - Wireless Application Protocol&lt;/h2&gt;
1678&lt;p&gt;Not that one! We are talking about Wireless Application Protocol and not Cardi
1679B&#39;s song 😃&lt;/p&gt;
1680&lt;p&gt;WAP stands for Wireless Application Protocol. It is a protocol designed for
1681micro-browsers, and it enables the access of internet in the mobile devices. It
1682uses the mark-up language WML (Wireless Markup Language and not HTML), WML is
1683defined as XML 1.0 application. Furthermore, it enables creating web
1684applications for mobile devices. In 1998, WAP Forum was founded by Ericson,
1685Motorola, Nokia and Unwired Planet whose aim was to standardize the various
1686wireless technologies via protocols.
1687&lt;a href=&#34;https://www.geeksforgeeks.org/wireless-application-protocol/&#34;&gt;(source)&lt;/a&gt;&lt;/p&gt;
1688&lt;p&gt;WAP protocol was resulted by the joint efforts of the various members of WAP
1689Forum. In 2002, WAP forum was merged with various other forums of the industry,
1690resulting in the formation of Open Mobile Alliance (OMA).
1691&lt;a href=&#34;https://www.geeksforgeeks.org/wireless-application-protocol/&#34;&gt;(source)&lt;/a&gt;&lt;/p&gt;
1692&lt;p&gt;These were some wild times. Devices had tiny screens and data transmission rates
1693were abominable. But they were capable of rendering WML (Wireless Markup
1694Language). This was very similar to HTML, actually. It is a markup language,
1695after all.&lt;/p&gt;
1696&lt;p&gt;These pages could be served by &lt;a href=&#34;https://apache.org/&#34;&gt;Apache&lt;/a&gt; and could be
1697generated by CGI scripts on the backend. The only difference was the limited
1698markup language.&lt;/p&gt;
1699&lt;h2 id=&#34;wml---wireless-markup-language&#34;&gt;WML - Wireless Markup Language&lt;/h2&gt;
1700&lt;p&gt;Just like web browsers use HTML for content structure, older mobile device
1701browsers use WML - if you need to support really old mobile phones using WML
1702browsers, you will need to know about it. WML is XML-based (an XML vocabulary
1703just like XHTML and MathML, but not HTML) and does not use the same metaphor as
1704HTML. HTML is a single document with some metadata packed away in the head, and
1705a body encapsulating the visible page. With WML, the metaphor does not envisage
1706a page, but rather a deck of cards. A WML file might have several pages or cards
1707contained within it.
1708&lt;a href=&#34;https://www.w3.org/wiki/Introduction_to_mobile_web&#34;&gt;(source)&lt;/a&gt;&lt;/p&gt;
1709&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;&amp;lt;?xml version=&amp;#34;1.0&amp;#34;?&amp;gt;&lt;/span&gt;
1710&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;&amp;lt;!DOCTYPE wml PUBLIC &amp;#34;-//WAPFORUM//DTD WML 1.1//EN&amp;#34; &amp;#34;http://www.wapforum.org/DTD/wml_1.1.xml&amp;#34;&amp;gt;&lt;/span&gt;
1711&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;lt;wml&amp;gt;
1712&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;card id=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;home&amp;#34;&lt;/span&gt; title=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Example Homepage&amp;#34;&lt;/span&gt;&amp;gt;
1713&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;p&amp;gt;Welcome to the Example homepage&amp;lt;/p&amp;gt;
1714&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/card&amp;gt;
1715&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;lt;/wml&amp;gt;
1716&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;There is an amazing tutorial on &lt;a href=&#34;https://www.tutorialspoint.com/wml/index.htm&#34;&gt;Tutorialpoint about
1717WML&lt;/a&gt;.&lt;/p&gt;
1718&lt;h2 id=&#34;converting-digg-to-wml&#34;&gt;Converting Digg to WML&lt;/h2&gt;
1719&lt;p&gt;This task is completely useless and not really feasible nowadays, but I had to
1720give it a try for old-time sake. Since the data is already there in a form of
1721RSS feed, I could take this feed and parse it and create a WML version of the
1722homepage.&lt;/p&gt;
1723&lt;p&gt;We will need:&lt;/p&gt;
1724&lt;ul&gt;
1725&lt;li&gt;Python3 &#43; Pip&lt;/li&gt;
1726&lt;li&gt;ImageMagick&lt;/li&gt;
1727&lt;li&gt;feedparser and mako templating&lt;/li&gt;
1728&lt;/ul&gt;
1729&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# for fedora 35&lt;/span&gt;
1730&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo dnf install ImageMagick python3-pip
1731&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1732&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# tempalting engine for python&lt;/span&gt;
1733&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;pip install mako --user
1734&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1735&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# for parsing rss feeds&lt;/span&gt;
1736&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;pip install feedparser --user
1737&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Project folder structure should look like the following.&lt;/p&gt;
1738&lt;pre&gt;&lt;code&gt;12:43:53 m@khan wap → tree -L 1
1739.
1740├── generate.py
1741└── template.wml
1742
1743&lt;/code&gt;&lt;/pre&gt;
1744&lt;p&gt;After that, I created a small template for the homepage.&lt;/p&gt;
1745&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;&amp;lt;?xml version=&amp;#34;1.0&amp;#34;?&amp;gt;&lt;/span&gt;
1746&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;&amp;lt;!DOCTYPE wml PUBLIC &amp;#34;-//WAPFORUM//DTD WML 1.2//EN&amp;#34; &amp;#34;http://www.wapforum.org/DTD/wml_1.2.xml&amp;#34;&amp;gt;&lt;/span&gt;
1747&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1748&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;lt;wml&amp;gt;
1749&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1750&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;card title=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Digg - What the Internet is talking about right now&amp;#34;&lt;/span&gt;&amp;gt;
1751&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1752&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; % for item in entries:
1753&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;p&amp;gt;&amp;lt;img src=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;/images/${item.id}.jpg&amp;#34;&lt;/span&gt; width=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;175&amp;#34;&lt;/span&gt; height=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;95&amp;#34;&lt;/span&gt; alt=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;${item.title}&amp;#34;&lt;/span&gt; /&amp;gt;&amp;lt;/p&amp;gt;
1754&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;p&amp;gt;&amp;lt;small&amp;gt;${item.kicker}&amp;lt;/small&amp;gt;&amp;lt;/p&amp;gt;
1755&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;p&amp;gt;&amp;lt;big&amp;gt;&amp;lt;b&amp;gt;${item.title}&amp;lt;/b&amp;gt;&amp;lt;/big&amp;gt;&amp;lt;/p&amp;gt;
1756&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;p&amp;gt;${item.description}&amp;lt;/p&amp;gt;
1757&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; % endfor
1758&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1759&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/card&amp;gt;
1760&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1761&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;lt;/wml&amp;gt;
1762&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;And the parser that parses RSS feed looks like this.&lt;/p&gt;
1763&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; os
1764&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; feedparser
1765&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;from&lt;/span&gt; mako.template &lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; Template
1766&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1767&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;os.system(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;mkdir -p www/images&amp;#39;&lt;/span&gt;)
1768&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1769&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;template = Template(filename=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;template.wml&amp;#39;&lt;/span&gt;)
1770&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1771&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;feed = feedparser.parse(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;https://digg.com/rss/top.xml&amp;#39;&lt;/span&gt;)
1772&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1773&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;entries = feed.entries[:15]
1774&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1775&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; entry &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; entries:
1776&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;Processing image with id &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;{}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;&lt;/span&gt;.format(entry.id))
1777&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; os.system(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;wget -q -O www/images/&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;{}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;.jpg &amp;#34;&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;{}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&amp;#39;&lt;/span&gt;.format(entry.id, entry.links[1].href))
1778&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; os.system(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;convert www/images/&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;{}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;.jpg -type Grayscale -resize 175x -depth 3 -quality 30 www/images/&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;{}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;.jpg&amp;#39;&lt;/span&gt;.format(entry.id, entry.id))
1779&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1780&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;html = template.render(entries = entries)
1781&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1782&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;with&lt;/span&gt; open(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;www/index.wml&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;w&#43;&amp;#39;&lt;/span&gt;) &lt;span style=&#34;color:#00f&#34;&gt;as&lt;/span&gt; fp:
1783&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; fp.write(html)
1784&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;This script will create a folder &lt;code&gt;www&lt;/code&gt; and in the folder &lt;code&gt;www/images&lt;/code&gt; for
1785storing resized images.&lt;/p&gt;
1786&lt;blockquote&gt;
1787&lt;p&gt;Be sure you don&#39;t use SSL and use just normal HTTP for serving the content.
1788These old phones will have problems with TLS 1.3 etc.&lt;/p&gt;
1789&lt;/blockquote&gt;
1790&lt;p&gt;If you look at the python file, I convert all the images into tiny B&amp;amp;W images.
1791They should be WBMP (Wireless BitMaP) but I choose JPEGs for this, and it seems
1792to work properly.&lt;/p&gt;
1793&lt;p&gt;Because I currently don&#39;t have a phone old enough to test it on, I used an
1794emulator. And it was really hard to find one. I found &lt;a href=&#34;http://wap-proof.sharewarejunction.com/&#34;&gt;WAP
1795Proof&lt;/a&gt; on shareware junction, and it
1796did the job well enough. I will try to find and actual device to test it on.&lt;/p&gt;
1797&lt;p&gt;&lt;video src=&#34;/posts/wap/emulator.mp4&#34; controls&gt;&lt;/video&gt;&lt;/p&gt;
1798&lt;p&gt;If you are using Nginx to serve the contents, add a directive to the hosts file
1799that will automatically server &lt;code&gt;index.wml&lt;/code&gt; file.&lt;/p&gt;
1800&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;server&lt;/span&gt; {
1801&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;index&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;index.wml&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;index.html&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;index.htm&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;index.nginx-debian.html&lt;/span&gt;;
1802&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
1803&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;conclusion&#34;&gt;Conclusion&lt;/h2&gt;
1804&lt;p&gt;Well, this was pointless, but very fun! I hope you enjoyed it as much as I did.
1805I will try to find an old phone to test it on. If you have any questions, feel
1806free to ask in the comments.&lt;/p&gt;
1807</content:encoded>
1808 </item>
1809
1810
1811
1812 <item>
1813 <title>Running Golang application as PID 1 with Linux kernel</title>
1814 <link>https://mitjafelicijan.com/running-golang-application-as-pid1.html</link>
1815 <pubDate>Sat, 25 Dec 2021 12:00:00 &#43;0200</pubDate>
1816 <guid>https://mitjafelicijan.com/running-golang-application-as-pid1.html</guid>
1817 <description>Unikernels, kernels, and alikeI have been reading a lot aboutunikernernels lately and found themvery intriguing.</description>
1818 <content:encoded>&lt;h2 id=&#34;unikernels-kernels-and-alike&#34;&gt;Unikernels, kernels, and alike&lt;/h2&gt;
1819&lt;p&gt;I have been reading a lot about
1820&lt;a href=&#34;https://en.wikipedia.org/wiki/Unikernel&#34;&gt;unikernernels&lt;/a&gt; lately and found them
1821very intriguing. When you push away all the marketing speak and look at the
1822idea, it makes a lot of sense.&lt;/p&gt;
1823&lt;blockquote&gt;
1824&lt;p&gt;A unikernel is a specialized, single address space machine image constructed
1825by using library operating systems. (&lt;a href=&#34;https://en.wikipedia.org/wiki/Unikernel&#34;&gt;Wikipedia&lt;/a&gt;)&lt;/p&gt;
1826&lt;/blockquote&gt;
1827&lt;p&gt;I really like the explanation from the article
1828&lt;a href=&#34;https://queue.acm.org/detail.cfm?id=2566628&#34;&gt;Unikernels: Rise of the Virtual Library Operating System&lt;/a&gt;.
1829Really worth a read.&lt;/p&gt;
1830&lt;p&gt;If we compare a normal operating system to a unikernel side by side, they would
1831look something like this.&lt;/p&gt;
1832&lt;figure&gt;
1833&lt;img src=&#34;/posts/pid1/unikernels.webp&#34; alt=&#34;Virtual machines vs Containers vs Unikernels&#34; /&gt;
1834&lt;/figure&gt;
1835&lt;p&gt;From this image, we can see how the complexity significantly decreases with
1836the use of Unikernels. This comes with a price, of course. Unikernels are hard
1837to get running and require a lot of work since you don&#39;t have an actual proper
1838kernel running in the background providing network access and drivers etc.&lt;/p&gt;
1839&lt;p&gt;So as a half step to make the stack simpler, I started looking into using
1840Linux kernel as a base and going from there. I came across this
1841&lt;a href=&#34;https://www.youtube.com/watch?v=Sk9TatW9ino&#34;&gt;Youtube video talking about Building the Simplest Possible Linux System&lt;/a&gt;
1842by &lt;a href=&#34;https://landley.net&#34;&gt;Rob Landley&lt;/a&gt; and apart from statically compiling the
1843application to be run as PID1 there was really no other obstacles.&lt;/p&gt;
1844&lt;h2 id=&#34;what-is-pid-1&#34;&gt;What is PID 1?&lt;/h2&gt;
1845&lt;p&gt;PID 1 is the first process that Linux kernel starts after the boot process.
1846It also has a couple of unique properties that are unique to it.&lt;/p&gt;
1847&lt;ul&gt;
1848&lt;li&gt;When the process with PID 1 dies for any reason, all other processes are
1849killed with KILL signal.&lt;/li&gt;
1850&lt;li&gt;When any process having children dies for any reason, its children are
1851re-parented to process with PID 1.&lt;/li&gt;
1852&lt;li&gt;Many signals which have default action of Term do not have one for PID 1.&lt;/li&gt;
1853&lt;li&gt;When the process with PID 1 dies for any reason, kernel panics, which
1854result in system crash.&lt;/li&gt;
1855&lt;/ul&gt;
1856&lt;p&gt;PID 1 is considered as an Init application which takes care of running other
1857and handling services like:&lt;/p&gt;
1858&lt;ul&gt;
1859&lt;li&gt;sshd,&lt;/li&gt;
1860&lt;li&gt;nginx,&lt;/li&gt;
1861&lt;li&gt;pulseaudio,&lt;/li&gt;
1862&lt;li&gt;etc.&lt;/li&gt;
1863&lt;/ul&gt;
1864&lt;p&gt;If you are on a Linux machine, you can check what your process is with PID 1
1865by running the following.&lt;/p&gt;
1866&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ cat /proc/1/status
1867&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Name: systemd
1868&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Umask: 0000
1869&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;State: S (sleeping)
1870&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Tgid: 1
1871&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Ngid: 0
1872&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Pid: 1
1873&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;PPid: 0
1874&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;...
1875&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;As we can see on my machine the process with id of 1 is &lt;a href=&#34;https://systemd.io/&#34;&gt;systemd&lt;/a&gt;
1876which is a software suite that provides an array of system components for Linux
1877operating systems. If you look closely you can also see that the &lt;code&gt;PPid&lt;/code&gt;
1878(process id of the parent process) is &lt;code&gt;0&lt;/code&gt; which additionally confirms that
1879this process doesn&#39;t have a parent.&lt;/p&gt;
1880&lt;h2 id=&#34;so-why-even-run-application-as-pid-1-instead-of-just-using-a-container&#34;&gt;So why even run application as PID 1 instead of just using a container?&lt;/h2&gt;
1881&lt;p&gt;Containers are wonderful, but they come with a lot of baggage. And because they
1882are in their nature layered, the images require quite a lot of space and also a
1883lot of additional software to handle them. They are not as lightweight as they
1884seem, and many popular images require 500 MB plus disk space.&lt;/p&gt;
1885&lt;p&gt;The idea of running this as PID 1 would result in a significantly smaller footprint,
1886as we will see later in the post.&lt;/p&gt;
1887&lt;blockquote&gt;
1888&lt;p&gt;You could run a simple init system inside Docker container described more
1889in this article &lt;a href=&#34;https://blog.phusion.nl/2015/01/20/docker-and-the-pid-1-zombie-reaping-problem/&#34;&gt;Docker and the PID 1 zombie reaping problem&lt;/a&gt;.&lt;/p&gt;
1890&lt;/blockquote&gt;
1891&lt;h2 id=&#34;the-master-plan&#34;&gt;The master plan&lt;/h2&gt;
1892&lt;ol&gt;
1893&lt;li&gt;Compile Linux kernel with the default definitions.&lt;/li&gt;
1894&lt;li&gt;Prepare a Hello World application in Golang that is statically compiled.&lt;/li&gt;
1895&lt;li&gt;Run it with &lt;a href=&#34;https://www.qemu.org/&#34;&gt;QEMU&lt;/a&gt; and providing Golang application
1896as init application / PID 1.&lt;/li&gt;
1897&lt;/ol&gt;
1898&lt;p&gt;For the sake of simplicity we will not be cross-compiling any of it and just
1899use the 64bit version.&lt;/p&gt;
1900&lt;h2 id=&#34;compiling-linux-kernel&#34;&gt;Compiling Linux kernel&lt;/h2&gt;
1901&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ wget https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.15.7.tar.xz
1902&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ tar xf linux-5.15.7.tar.xz
1903&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1904&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ cd linux-5.15.7
1905&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1906&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ make clean
1907&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1908&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# read more about this https://stackoverflow.com/a/41886394&lt;/span&gt;
1909&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ make defconfig
1910&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1911&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ time make -j &lt;span style=&#34;color:#a31515&#34;&gt;`&lt;/span&gt;nproc&lt;span style=&#34;color:#a31515&#34;&gt;`&lt;/span&gt;
1912&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1913&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ cd ..
1914&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;At this point we have kernel image that is located in &lt;code&gt;arch/x86_64/boot/bzImage&lt;/code&gt;.
1915We will use this in QEMU later.&lt;/p&gt;
1916&lt;p&gt;To make our lives a bit easier lets move the kernel image to another place.
1917Lets create a folder &lt;code&gt;bin/&lt;/code&gt; in the root of our project with &lt;code&gt;mkdir -p bin&lt;/code&gt;.&lt;/p&gt;
1918&lt;p&gt;At this point we can copy &lt;code&gt;bzImage&lt;/code&gt; to &lt;code&gt;bin/&lt;/code&gt; folder with
1919&lt;code&gt;cp linux-5.15.7/arch/x86_64/boot/bzImage bin/bzImage&lt;/code&gt;.&lt;/p&gt;
1920&lt;p&gt;The folder structure of this experiment should look like this.&lt;/p&gt;
1921&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;pid1/
1922&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; bin/
1923&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; bzImage
1924&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; linux-5.15.7/
1925&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; linux-5.15.7.tar.xz
1926&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;preparing-pid-1-application-in-golang&#34;&gt;Preparing PID 1 application in Golang&lt;/h2&gt;
1927&lt;p&gt;This step is relatively easy. The only thing we must have in mind that we will
1928need to compile the binary as a static one.&lt;/p&gt;
1929&lt;p&gt;Let&#39;s create &lt;code&gt;init.go&lt;/code&gt; file in the root of the project.&lt;/p&gt;
1930&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;package&lt;/span&gt; main
1931&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1932&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; (
1933&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;fmt&amp;#34;&lt;/span&gt;
1934&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;time&amp;#34;&lt;/span&gt;
1935&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;)
1936&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1937&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;func&lt;/span&gt; main() {
1938&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; {
1939&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; fmt.Println(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Hello from Golang&amp;#34;&lt;/span&gt;)
1940&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; time.Sleep(1 * time.Second)
1941&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
1942&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
1943&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;If you notice, we have a forever loop in the main, with a simple sleep of 1
1944second to not overwhelm the CPU. This is because PID 1 should never complete
1945and/or exit. That would result in a kernel panic. Which is BAD!&lt;/p&gt;
1946&lt;p&gt;There are two ways of compiling Golang application. Statically and dynamically.&lt;/p&gt;
1947&lt;p&gt;To statically compile the binary, use the following command.&lt;/p&gt;
1948&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ go build -ldflags=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;-extldflags=-static&amp;#34;&lt;/span&gt; init.go
1949&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;We can also check if the binary is statically compiled with:&lt;/p&gt;
1950&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ file init
1951&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;init: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, Go BuildID=Ypu8Zw_4NBxm1Yxg2OYO/H5x721rQ9uTPiDVh-VqP/vZN7kXfGG1zhX_qdHMgH/9vBfmK81tFrygfOXDEOo, not stripped
1952&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
1953&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ ldd init
1954&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;not a dynamic executable
1955&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;At this point, we need to create &lt;a href=&#34;https://www.linuxfromscratch.org/blfs/view/svn/postlfs/initramfs.html&#34;&gt;initramfs&lt;/a&gt;
1956(abbreviated from &amp;quot;initial RAM file system&amp;quot;, is the successor of initrd. It
1957is a cpio archive of the initial file system that gets loaded into memory
1958during the Linux startup process).&lt;/p&gt;
1959&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ echo init | cpio -o --format=newc &amp;gt; initramfs
1960&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ mv initramfs bin/initramfs
1961&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;The projects at this stage should look like this.&lt;/p&gt;
1962&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;pid1/
1963&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; bin/
1964&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; bzImage
1965&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; initramfs
1966&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; linux-5.15.7/
1967&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; linux-5.15.7.tar.xz
1968&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; init.go
1969&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;running-all-of-it-with-qemu&#34;&gt;Running all of it with QEMU&lt;/h2&gt;
1970&lt;p&gt;&lt;a href=&#34;https://www.qemu.org/&#34;&gt;QEMU&lt;/a&gt; is a free and open-source hypervisor. It emulates
1971the machine&#39;s processor through dynamic binary translation and provides a set
1972of different hardware and device models for the machine, enabling it to run a
1973variety of guest operating systems.&lt;/p&gt;
1974&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ qemu-system-x86_64 -serial stdio -kernel bin/bzImage -initrd bin/initramfs -append &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;console=ttyS0&amp;#34;&lt;/span&gt; -m 128
1975&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ qemu-system-x86_64 -serial stdio -kernel bin/bzImage -initrd bin/initramfs -append &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;console=ttyS0&amp;#34;&lt;/span&gt; -m 128
1976&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 0.000000] Linux version 5.15.7 (m@khan) (gcc (GCC) 11.2.1 20211203 (Red Hat 11.2.1-7), GNU ld version 2.37-10.fc35) &lt;span style=&#34;color:#008000&#34;&gt;#7 SMP Mon Dec 13 10:23:25 CET 2021&lt;/span&gt;
1977&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 0.000000] Command line: console=ttyS0
1978&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 0.000000] x86/fpu: x87 FPU will use FXSAVE
1979&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 0.000000] signal: max sigframe size: 1440
1980&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 0.000000] BIOS-provided physical RAM map:
1981&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable
1982&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved
1983&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved
1984&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x0000000007fdffff] usable
1985&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 0.000000] BIOS-e820: [mem 0x0000000007fe0000-0x0000000007ffffff] reserved
1986&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 0.000000] BIOS-e820: [mem 0x00000000fffc0000-0x00000000ffffffff] reserved
1987&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 0.000000] NX (Execute Disable) protection: active
1988&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 0.000000] SMBIOS 2.8 present.
1989&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 0.000000] DMI: QEMU Standard PC (i440FX &#43; PIIX, 1996), BIOS 1.14.0-6.fc35 04/01/2014
1990&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 0.000000] tsc: Fast TSC calibration failed
1991&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;...
1992&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 2.016106] ALSA device list:
1993&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 2.016329] No soundcards found.
1994&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 2.053176] Freeing unused kernel image (initmem) memory: 1368K
1995&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 2.056095] Write protecting the kernel read-only data: 20480k
1996&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 2.058248] Freeing unused kernel image (text/rodata gap) memory: 2032K
1997&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 2.058811] Freeing unused kernel image (rodata/data gap) memory: 500K
1998&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 2.059164] Run /init as init process
1999&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Hello from Golang
2000&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 2.386879] tsc: Refined TSC clocksource calibration: 3192.032 MHz
2001&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 2.387114] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x2e02e31fa14, max_idle_ns: 440795264947 ns
2002&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 2.387380] clocksource: Switched to clocksource tsc
2003&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[ 2.587895] input: ImExPS/2 Generic Explorer Mouse as /devices/platform/i8042/serio1/input/input3
2004&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Hello from Golang
2005&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Hello from Golang
2006&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Hello from Golang
2007&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;The whole &lt;a href=&#34;/posts/pid1/qemu.log&#34;&gt;log file here&lt;/a&gt;.&lt;/p&gt;
2008&lt;h2 id=&#34;size-comparison&#34;&gt;Size comparison&lt;/h2&gt;
2009&lt;p&gt;The cool thing about this approach is that the Linux kernel and the application
2010together only take around 12 MB, which is impressive as hell. And we need to
2011also know that the size of bzImage (Linux kernel) could be greatly decreased
2012by going into &lt;code&gt;make menuconfig&lt;/code&gt; and removing a ton of features from the kernel,
2013making the size even smaller. I managed to get kernel size down to 2 MB and
2014still working properly.&lt;/p&gt;
2015&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;total 12M
2016&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;-rw-r--r--. 1 m m 9.3M Dec 13 10:24 bzImage
2017&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;-rw-r--r--. 1 m m 1.9M Dec 27 01:19 initramfs
2018&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;creating-iso-image-and-running-it-with-gnome-boxes&#34;&gt;Creating ISO image and running it with Gnome Boxes&lt;/h2&gt;
2019&lt;p&gt;First we need to create proper folder structure with &lt;code&gt;mkdir -p iso/boot/grub&lt;/code&gt;.&lt;/p&gt;
2020&lt;p&gt;Then we need to download the &lt;a href=&#34;https://github.com/littleosbook/littleosbook/raw/master/files/stage2_eltorito&#34;&gt;grub binary&lt;/a&gt;.
2021You can read more about this program on &lt;a href=&#34;https://github.com/littleosbook/littleosbook&#34;&gt;https://github.com/littleosbook/littleosbook&lt;/a&gt;.&lt;/p&gt;
2022&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ wget -O iso/boot/grub/stage2_eltorito https://github.com/littleosbook/littleosbook/raw/master/files/stage2_eltorito
2023&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ tree iso/boot/
2024&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;iso/boot/
2025&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;├── bzImage
2026&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;├── grub
2027&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;│   ├── menu.lst
2028&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;│   └── stage2_eltorito
2029&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;└── initramfs
2030&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Let&#39;s copy files into proper folders.&lt;/p&gt;
2031&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ cp stage2_eltorito iso/boot/grub/
2032&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ cp bin/bzImage iso/boot/
2033&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ cp bin/initramfs iso/boot/
2034&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Lets create a GRUB config file at &lt;code&gt;nano iso/boot/grub/menu.lst&lt;/code&gt; with contents.&lt;/p&gt;
2035&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;default=&lt;span style=&#34;color:#a31515&#34;&gt;0&lt;/span&gt;
2036&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;timeout=&lt;span style=&#34;color:#a31515&#34;&gt;5&lt;/span&gt;
2037&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2038&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;title GoAsPID1
2039&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;kernel /boot/bzImage
2040&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;initrd /boot/initramfs
2041&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Let&#39;s create iso file by using genisoimage:&lt;/p&gt;
2042&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;genisoimage -R &lt;span style=&#34;color:#a31515&#34;&gt;\
2043&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; -b boot/grub/stage2_eltorito &lt;span style=&#34;color:#a31515&#34;&gt;\
2044&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; -no-emul-boot &lt;span style=&#34;color:#a31515&#34;&gt;\
2045&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; -boot-load-size 4 &lt;span style=&#34;color:#a31515&#34;&gt;\
2046&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; -A os &lt;span style=&#34;color:#a31515&#34;&gt;\
2047&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; -input-charset utf8 &lt;span style=&#34;color:#a31515&#34;&gt;\
2048&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; -quiet &lt;span style=&#34;color:#a31515&#34;&gt;\
2049&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; -boot-info-table &lt;span style=&#34;color:#a31515&#34;&gt;\
2050&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; -o GoAsPID1.iso &lt;span style=&#34;color:#a31515&#34;&gt;\
2051&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; iso
2052&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;This will produce &lt;code&gt;GoAsPID1.iso&lt;/code&gt; which you can use with &lt;a href=&#34;https://www.virtualbox.org/&#34;&gt;Virtualbox&lt;/a&gt;
2053or &lt;a href=&#34;https://apps.gnome.org/app/org.gnome.Boxes/&#34;&gt;Gnome Boxes&lt;/a&gt;.&lt;/p&gt;
2054&lt;p&gt;&lt;video src=&#34;/posts/pid1/boxes.mp4&#34; controls&gt;&lt;/video&gt;&lt;/p&gt;
2055&lt;h2 id=&#34;is-running-applications-as-pid-1-even-worth-it&#34;&gt;Is running applications as PID 1 even worth it?&lt;/h2&gt;
2056&lt;p&gt;Well, the answer to this is not as simple as one would think. Sometimes it is
2057and sometimes it&#39;s not. For embedded systems and very specialized applications
2058it is worth for sure. But in normal uses, I don&#39;t think so. It was an interesting
2059exercise in compiling kernels and looking at the guts of the Linux kernel,
2060but sticking to containers for most of the things is a better option in my
2061opinion.&lt;/p&gt;
2062&lt;p&gt;An interesting experiment would be creating an image that supports networking
2063and could be deployed to AWS as an EC2 instance and observing how it fares.
2064But in that case, we would need to write some sort of supervisor that would
2065run on a separate EC2 that would check if other EC2 instances are running
2066properly. Remember that if your application fails, kernel panics and the
2067whole machine is inoperable in this case.&lt;/p&gt;
2068</content:encoded>
2069 </item>
2070
2071
2072
2073 <item>
2074 <title>Debian based riced up distribution for Developers and DevOps folks</title>
2075 <link>https://mitjafelicijan.com/debian-based-riced-up-distribution-for-developers-and-devops-folks.html</link>
2076 <pubDate>Fri, 03 Dec 2021 12:00:00 &#43;0200</pubDate>
2077 <guid>https://mitjafelicijan.com/debian-based-riced-up-distribution-for-developers-and-devops-folks.html</guid>
2078 <description>IntroductionI have been using Ubuntu for quite a longtime now.</description>
2079 <content:encoded>&lt;h2 id=&#34;introduction&#34;&gt;Introduction&lt;/h2&gt;
2080&lt;p&gt;I have been using &lt;a href=&#34;https://ubuntu.com/&#34;&gt;Ubuntu&lt;/a&gt; for quite a longtime now. I have
2081used &lt;a href=&#34;https://www.debian.org/&#34;&gt;Debian&lt;/a&gt; in the past and
2082&lt;a href=&#34;https://manjaro.org/&#34;&gt;Manjaro&lt;/a&gt;. Also had &lt;a href=&#34;https://archlinux.org/&#34;&gt;Arch&lt;/a&gt; for
2083some time and even ran &lt;a href=&#34;https://www.gentoo.org/&#34;&gt;Gentoo&lt;/a&gt; way back.&lt;/p&gt;
2084&lt;p&gt;What I learned from all this is that I prefer running a bit older versions and
2085having them be stable than run bleeding edge rolling release. For that reason, I
2086stuck with Ubuntu for a couple of years now. I am also at a point in my life
2087where I just don&#39;t care what is cool or hip anymore. I just want a stable system
2088that doesn&#39;t get in my way.&lt;/p&gt;
2089&lt;p&gt;During all this, I noticed that these distributions were getting very bloated
2090and a lot of software got included that I usually uninstall on fresh
2091installation. Maybe this is my OCD speaking, but why do I have to give fresh
2092installation min 1 GB of ram out of the box just to have a blank screen in front
2093of me? I get it, there are many things included in the distro to make my life
2094easier. I understand. But at this point I have a feeling that modern Linux
2095distributions are becoming similar to &lt;a href=&#34;https://devhumor.com/content/uploads/images/August2017/node-modules.jpg&#34;&gt;Node.js project with
2096node_modules&lt;/a&gt;.
2097Just a crazy number of packages serving very little or no purpose, just
2098supporting other software.&lt;/p&gt;
2099&lt;p&gt;I felt I needed a fresh start. To start over with something minimal and clean.
2100Something that would put a little more joy into using a computer again.&lt;/p&gt;
2101&lt;p&gt;For the first version, I wanted to target the following machines I have at home
2102that I want this thing to work on.&lt;/p&gt;
2103&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# My main stationary work machine&lt;/span&gt;
2104&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Resolution: 3840x1080 (Super Ultrawide Monitor 32:9)
2105&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;CPU: Intel i7-8700 (12) @ 4.600GHz
2106&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;GPU: AMD ATI Radeon RX 470/480/570/570X/580/580X/590
2107&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Memory: 32020MiB
2108&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# Thinkpad x220 for testing things and goofing around&lt;/span&gt;
2109&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Resolution: 1366x768
2110&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;CPU: Intel i5-2520M (4) @ 3.200GHz
2111&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;GPU: Intel 2nd Generation Core Processor Family
2112&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Memory: 15891MiB
2113&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;how-should-i-approach-this&#34;&gt;How should I approach this?&lt;/h2&gt;
2114&lt;p&gt;I knew I wanted to use &lt;a href=&#34;https://www.debian.org/CD/netinst/&#34;&gt;minimal Debian netinst
2115&lt;/a&gt; for the base to give myself a head
2116start. No reason to go through changing the installer and also testing all that
2117behemoth of a thing. So, some sort of ricing was the only logical option to get
2118this thing of the grounds somewhat quickly.&lt;/p&gt;
2119&lt;blockquote&gt;
2120&lt;p&gt;&lt;strong&gt;What is ricing anyway?&lt;/strong&gt;
2121The term “RICE” stands for Race Inspired Cosmetic Enhancement. A group of
2122people (could be one, idk) decided to see if they could tweak their own
2123distros like they/others did their cars. This gave rise to a community of
2124Linux/Unix enthusiasts trying to make their distros look cooler and better
2125than others... For more information, read this article
2126&lt;a href=&#34;https://pesos.github.io/2020/07/14/what-is-ricing.html&#34;&gt;What in the world is ricing!?&lt;/a&gt;.&lt;/p&gt;
2127&lt;/blockquote&gt;
2128&lt;p&gt;I didn&#39;t want this to just be a set of config files for theming purpose. I
2129wanted this to include a set of pre-installed tools and services that are being
2130used all the time by a modern developer. Theming is just a tiny part of it.
2131Fonts being applied across the distro and things like that.&lt;/p&gt;
2132&lt;p&gt;First, I choose terminal installer and left it to load additional components.
2133Avoid using graphical installer in this case.&lt;/p&gt;
2134&lt;figure&gt;
2135&lt;img src=&#34;/posts/dfd-rice/install-00.png&#34; alt=&#34;&#34; /&gt;
2136&lt;/figure&gt;
2137&lt;p&gt;After that I selected hostname and created a normal user and set password for
2138that user and root user and choose guided mode for disk partitioning.&lt;/p&gt;
2139&lt;figure&gt;
2140&lt;img src=&#34;/posts/dfd-rice/install-01.png&#34; alt=&#34;&#34; /&gt;
2141&lt;/figure&gt;
2142&lt;p&gt;I left it run to install all the things required for the base system and opted
2143out of scanning additional media for use by the package manager. Those will be
2144downloaded from the internet during installation.&lt;/p&gt;
2145&lt;figure&gt;
2146&lt;img src=&#34;/posts/dfd-rice/install-02.png&#34; alt=&#34;&#34; /&gt;
2147&lt;/figure&gt;
2148&lt;p&gt;I opted out of the popularity contest, and &lt;strong&gt;now comes the important part&lt;/strong&gt;.
2149Uncheck all the boxes in Software selection and only leave &#39;standard system
2150utilities&#39;. I also left an SSH server, so I was able to log in to the machine
2151from my main PC.&lt;/p&gt;
2152&lt;figure&gt;
2153&lt;img src=&#34;/posts/dfd-rice/install-03.png&#34; alt=&#34;&#34; /&gt;
2154&lt;/figure&gt;
2155&lt;p&gt;At this point, I installed GRUB bootloader on the disk where I installed the
2156system.&lt;/p&gt;
2157&lt;figure&gt;
2158&lt;img src=&#34;/posts/dfd-rice/install-04.png&#34; alt=&#34;&#34; /&gt;
2159&lt;/figure&gt;
2160&lt;p&gt;That concluded the installation of base Debian and after restarting the computer
2161I was prompted with the login screen.&lt;/p&gt;
2162&lt;figure&gt;
2163&lt;img src=&#34;/posts/dfd-rice/install-05.png&#34; alt=&#34;&#34; /&gt;
2164&lt;/figure&gt;
2165&lt;p&gt;Now that I had the base installation, it was time to choose what software do I
2166want to include in this so-called distribution. I wanted out of the box
2167developer experience, so I had plenty to choose.&lt;/p&gt;
2168&lt;p&gt;Let&#39;s not waste time and go through the list.&lt;/p&gt;
2169&lt;h2 id=&#34;desktop-environments&#34;&gt;Desktop environments&lt;/h2&gt;
2170&lt;p&gt;I have been using &lt;a href=&#34;https://www.gnome.org/&#34;&gt;Gnome&lt;/a&gt; for my whole Linux life. From
2171version 2 forward. It&#39;s been quite a ride. I hated version 3 when it came out
2172and replaced version 2. But I got used to it. And now with version 40&#43; they also
2173made couple of changes which I found both frustrating and presently surprised.&lt;/p&gt;
2174&lt;p&gt;The amount of vertical space you loose because of the beefy title bars on
2175windows is ridiculous. And then in case of
2176&lt;a href=&#34;https://gnunn1.github.io/tilix-web/&#34;&gt;Tilix&lt;/a&gt; you also have tabs, and you are
2177100px deep. Vertical space is one of the most important things for a
2178developer. The more real estate you have, the more code you can have in a
2179viewport.&lt;/p&gt;
2180&lt;p&gt;But on the other hand, I still love how Gnome feels and looks. I gotta give them
2181that. They really are trying to make Gnome feel unified and modern.&lt;/p&gt;
2182&lt;p&gt;Regardless of all the nice things Gnome has, I was looking at the tiling window
2183managers for some time, but never had the nerve to actually go with it. But now
2184was the ideal time to give it a go. No guts, no glory kind of a thing.&lt;/p&gt;
2185&lt;p&gt;One of the requirements for me was easy custom layouts because I use a really
2186strange monitor with aspect ratio of 32:9. So relying on included layouts most
2187of them have is a non-starter.&lt;/p&gt;
2188&lt;p&gt;What I was doing in Gnome was having windows in a layout like the diagram
2189below. This is my common practice. And if you look at it you can clearly see I
2190was replicating tiling window manager setup in Gnome.&lt;/p&gt;
2191&lt;figure&gt;
2192&lt;img src=&#34;/posts/dfd-rice/layout.png&#34; alt=&#34;&#34; /&gt;
2193&lt;/figure&gt;
2194&lt;p&gt;That made me look into a bunch of tiling window managers and then tested them
2195out. Candidates I was looking at were:&lt;/p&gt;
2196&lt;ul&gt;
2197&lt;li&gt;&lt;a href=&#34;https://i3wm.org/&#34;&gt;i3&lt;/a&gt;&lt;/li&gt;
2198&lt;li&gt;&lt;a href=&#34;https://github.com/baskerville/bspwm&#34;&gt;bspwm&lt;/a&gt;&lt;/li&gt;
2199&lt;li&gt;&lt;a href=&#34;https://awesomewm.org/index.html&#34;&gt;awesome&lt;/a&gt;&lt;/li&gt;
2200&lt;li&gt;&lt;a href=&#34;https://xmonad.org/&#34;&gt;XMonad&lt;/a&gt;&lt;/li&gt;
2201&lt;li&gt;&lt;a href=&#34;https://swaywm.org/&#34;&gt;sway&lt;/a&gt;&lt;/li&gt;
2202&lt;li&gt;&lt;a href=&#34;http://www.qtile.org/&#34;&gt;Qtile&lt;/a&gt;&lt;/li&gt;
2203&lt;li&gt;&lt;a href=&#34;https://dwm.suckless.org/&#34;&gt;dwm&lt;/a&gt;&lt;/li&gt;
2204&lt;/ul&gt;
2205&lt;p&gt;You can also check article &lt;a href=&#34;https://www.tecmint.com/best-tiling-window-managers-for-linux/&#34;&gt;13 Best Tiling Window Managers for
2206Linux&lt;/a&gt; I was
2207referencing while testing them out.&lt;/p&gt;
2208&lt;p&gt;While all of them provided what I needed, I liked i3 the most. What particular
2209caught my eye was the ease to use and tree based layouts which allows flexible
2210layouts. I know others can be set up also to have custom layouts other than&lt;br /&gt;
2211spiral, dwindle etc. I think i3 is a good entry-level window manager for
2212somebody like me.&lt;/p&gt;
2213&lt;h2 id=&#34;batteries-included&#34;&gt;Batteries included&lt;/h2&gt;
2214&lt;p&gt;The source for the whole thing is located on Github
2215&lt;a href=&#34;https://github.com/mitjafelicijan/dfd-rice&#34;&gt;https://github.com/mitjafelicijan/dfd-rice&lt;/a&gt;.&lt;/p&gt;
2216&lt;p&gt;Currenly included:&lt;/p&gt;
2217&lt;ul&gt;
2218&lt;li&gt;&lt;code&gt;non-free&lt;/code&gt; (enables non-free packages in apt)&lt;/li&gt;
2219&lt;li&gt;&lt;code&gt;sudo&lt;/code&gt; (adds sudo and adds user to sudo group)&lt;/li&gt;
2220&lt;li&gt;&lt;code&gt;essentials&lt;/code&gt; (gcc, htop, zip, curl, etc...)&lt;/li&gt;
2221&lt;li&gt;&lt;code&gt;wifi&lt;/code&gt; (network manager nmtui)&lt;/li&gt;
2222&lt;li&gt;&lt;code&gt;desktop&lt;/code&gt; (i3, dmenu, fonts, configurations)&lt;/li&gt;
2223&lt;li&gt;&lt;code&gt;pulseaudio&lt;/code&gt; (pulseaudio with pavucontrol)&lt;/li&gt;
2224&lt;li&gt;&lt;code&gt;code-editors&lt;/code&gt; (vim, micro, vscode)&lt;/li&gt;
2225&lt;li&gt;&lt;code&gt;ohmybash&lt;/code&gt; (make bash pretty)&lt;/li&gt;
2226&lt;li&gt;&lt;code&gt;file-managers&lt;/code&gt; (mc)&lt;/li&gt;
2227&lt;li&gt;&lt;code&gt;git-ui&lt;/code&gt; (terminal git gui)&lt;/li&gt;
2228&lt;li&gt;&lt;code&gt;meld&lt;/code&gt; (diff tool)&lt;/li&gt;
2229&lt;li&gt;&lt;code&gt;profiling&lt;/code&gt; (kcachegrind, valgrind, strace, ltrace)&lt;/li&gt;
2230&lt;li&gt;&lt;code&gt;browsers&lt;/code&gt; (brave, firefox, chromium)&lt;/li&gt;
2231&lt;li&gt;programming languages:
2232&lt;ul&gt;
2233&lt;li&gt;&lt;code&gt;python&lt;/code&gt;&lt;/li&gt;
2234&lt;li&gt;&lt;code&gt;golang&lt;/code&gt;&lt;/li&gt;
2235&lt;li&gt;&lt;code&gt;nodejs&lt;/code&gt;&lt;/li&gt;
2236&lt;li&gt;&lt;code&gt;rust&lt;/code&gt;&lt;/li&gt;
2237&lt;li&gt;&lt;code&gt;nim&lt;/code&gt;&lt;/li&gt;
2238&lt;li&gt;&lt;code&gt;php&lt;/code&gt;&lt;/li&gt;
2239&lt;li&gt;&lt;code&gt;ruby&lt;/code&gt;&lt;/li&gt;
2240&lt;/ul&gt;
2241&lt;/li&gt;
2242&lt;li&gt;&lt;code&gt;docker&lt;/code&gt; (with docker-compose)&lt;/li&gt;
2243&lt;li&gt;&lt;code&gt;ansible&lt;/code&gt;&lt;/li&gt;
2244&lt;/ul&gt;
2245&lt;p&gt;Install script also allows you to install only specific packages (example for:
2246essentials ohmybash docker rust).&lt;/p&gt;
2247&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;su - root &lt;span style=&#34;color:#a31515&#34;&gt;\
2248&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; bash -c &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;$(&lt;/span&gt;wget -q https://raw.github.com/mitjafelicijan/dfd-rice/master/tools/install.sh -O -&lt;span style=&#34;color:#00f&#34;&gt;)&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt; -- &lt;span style=&#34;color:#a31515&#34;&gt;\
2249&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; essentials ohmybash docker rust
2250&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Currently, most of these recipes use what Debian and this is totally fine with
2251me since I never use bleeding edge features of a package. But if something major
2252would come to light, I will replace it with a possible compilation script or
2253something similar.&lt;/p&gt;
2254&lt;p&gt;This is some of the output from the installation script.&lt;/p&gt;
2255&lt;figure&gt;
2256&lt;img src=&#34;/posts/dfd-rice/script.png&#34; alt=&#34;&#34; /&gt;
2257&lt;/figure&gt;
2258&lt;p&gt;Let&#39;s take a look at some examples in the installation script.&lt;/p&gt;
2259&lt;h3 id=&#34;docker-recipe&#34;&gt;Docker recipe&lt;/h3&gt;
2260&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# docker&lt;/span&gt;
2261&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print_header &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Installing Docker&amp;#34;&lt;/span&gt;
2262&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;curl -fsSL https://download.docker.com/linux/debian/gpg | gpg --yes --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
2263&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;echo &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;deb [arch=&lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;$(&lt;/span&gt;dpkg --print-architecture&lt;span style=&#34;color:#00f&#34;&gt;)&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/debian &lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;$(&lt;/span&gt;lsb_release -cs&lt;span style=&#34;color:#00f&#34;&gt;)&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; stable&amp;#34;&lt;/span&gt; | tee /etc/apt/sources.list.d/docker.list &amp;gt; /dev/null
2264&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;apt update
2265&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;apt -y install docker-ce docker-ce-cli containerd.io docker-compose
2266&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2267&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;systemctl start docker
2268&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;systemctl enable docker
2269&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;systemctl status docker --no-pager
2270&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2271&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;/sbin/usermod -aG docker $USERNAME
2272&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h3 id=&#34;making-bash-pretty&#34;&gt;Making bash pretty&lt;/h3&gt;
2273&lt;p&gt;I really like &lt;a href=&#34;https://ohmyz.sh/&#34;&gt;Oh My Zsh&lt;/a&gt;, but I don&#39;t like zsh shell. When
2274I used it, I constantly needed to be aware of it and running bash scripts was a
2275pain. So, I was really delighted when I found out that a version for bash
2276existed called &lt;a href=&#34;https://ohmybash.nntoan.com/&#34;&gt;Oh My Bash&lt;/a&gt;. Let&#39;s take a look at
2277the recipe for installing it.&lt;/p&gt;
2278&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# ohmybash&lt;/span&gt;
2279&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print_header &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Enabling OhMyBash&amp;#34;&lt;/span&gt;
2280&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo -u $USERNAME sh -c &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;$(&lt;/span&gt;curl -fsSL https://raw.github.com/ohmybash/oh-my-bash/master/tools/install.sh&lt;span style=&#34;color:#00f&#34;&gt;)&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt; &amp;amp;
2281&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;T1=&lt;span style=&#34;color:#a31515&#34;&gt;${&lt;/span&gt;!&lt;span style=&#34;color:#a31515&#34;&gt;}&lt;/span&gt;
2282&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;wait &lt;span style=&#34;color:#a31515&#34;&gt;${&lt;/span&gt;T1&lt;span style=&#34;color:#a31515&#34;&gt;}&lt;/span&gt;
2283&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Because OhMyBash does &lt;code&gt;exec bash&lt;/code&gt; at the end, this traps our script inside
2284another shell and our script cannot continue. For that reason, I executed this
2285in background. But that presents a new problem. Because this is executed in
2286background, we lose track of progress naturally. And that strange trick with
2287&lt;code&gt;T1=${!}&lt;/code&gt; and &lt;code&gt;wait ${T1}&lt;/code&gt; waits for the background process to finish before
2288continuing to another task in bash script.&lt;/p&gt;
2289&lt;p&gt;Check &lt;a href=&#34;https://www.cloudsavvyit.com/12277/how-to-use-multi-threaded-processing-in-bash-scripts/&#34;&gt;Multi-Threaded Processing in Bash Scripts&lt;/a&gt;
2290for more details.&lt;/p&gt;
2291&lt;h2 id=&#34;conclusion&#34;&gt;Conclusion&lt;/h2&gt;
2292&lt;p&gt;Take a look at
2293&lt;a href=&#34;https://github.com/mitjafelicijan/dfd-rice/blob/develop/tools/install.sh&#34;&gt;https://github.com/mitjafelicijan/dfd-rice/blob/develop/tools/install.sh&lt;/a&gt; script
2294to get familiar with it. This is just a first iteration and I will continue to
2295update it because I need this in my life.&lt;/p&gt;
2296&lt;p&gt;The current version boots in 4s to the login prompt, and after you log in, the
2297desktop environment loads in 2s. So, its fast, very fast. And on clean boot, I
2298measured ~230 MB of RAM usage.&lt;/p&gt;
2299&lt;p&gt;And this is how it looks with two terminals side by side. I really like the
2300simplicity and clean interface. I will polish the colors and stuff like that,
2301but I really do like the results.&lt;/p&gt;
2302&lt;figure&gt;
2303&lt;img src=&#34;/posts/dfd-rice/desktop.png&#34; alt=&#34;&#34; /&gt;
2304&lt;/figure&gt;
2305</content:encoded>
2306 </item>
2307
2308
2309
2310 <item>
2311 <title>List of essential Linux commands for server management</title>
2312 <link>https://mitjafelicijan.com/linux-cheatsheet.html</link>
2313 <pubDate>Sun, 01 Aug 2021 12:00:00 &#43;0200</pubDate>
2314 <guid>https://mitjafelicijan.com/linux-cheatsheet.html</guid>
2315 <description>Generate SSH keyssh-keygen -t ed25519 -C &amp;#34;your_email@example.</description>
2316 <content:encoded>&lt;p&gt;&lt;strong&gt;Generate SSH key&lt;/strong&gt;&lt;/p&gt;
2317&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ssh-keygen -t ed25519 -C &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;your_email@example.com&amp;#34;&lt;/span&gt;
2318&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2319&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# when no support for Ed25519 present&lt;/span&gt;
2320&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ssh-keygen -t rsa -b 4096 -C &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;your_email@example.com&amp;#34;&lt;/span&gt;
2321&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Note: By default SSH keys get stored to &lt;code&gt;/home/&amp;lt;username&amp;gt;/.ssh/&lt;/code&gt; folder.&lt;/p&gt;
2322&lt;p&gt;&lt;strong&gt;Login to host via SSH&lt;/strong&gt;&lt;/p&gt;
2323&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# connect to host as your local username&lt;/span&gt;
2324&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ssh host
2325&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2326&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# connect to host as user&lt;/span&gt;
2327&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ssh &amp;lt;user&amp;gt;@&amp;lt;host&amp;gt;
2328&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2329&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# connect to host using port&lt;/span&gt;
2330&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ssh -p &amp;lt;port&amp;gt; &amp;lt;user&amp;gt;@&amp;lt;host&amp;gt;
2331&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Execute command on a server through SSH&lt;/strong&gt;&lt;/p&gt;
2332&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# execute one command&lt;/span&gt;
2333&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ssh root@100.100.100.100 &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;ls /root&amp;#34;&lt;/span&gt;
2334&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2335&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# execute many commands&lt;/span&gt;
2336&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ssh root@100.100.100.100 &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;cd /root;touch file.txt&amp;#34;&lt;/span&gt;
2337&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Displays currently logged in users in the system&lt;/strong&gt;&lt;/p&gt;
2338&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;w
2339&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Displays Linux system information&lt;/strong&gt;&lt;/p&gt;
2340&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;uname
2341&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Displays kernel release information&lt;/strong&gt;&lt;/p&gt;
2342&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;uname -r
2343&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Shows the system hostname&lt;/strong&gt;&lt;/p&gt;
2344&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;hostname
2345&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Shows system reboot history&lt;/strong&gt;&lt;/p&gt;
2346&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;last reboot
2347&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Displays information about the user&lt;/strong&gt;&lt;/p&gt;
2348&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo apt install finger
2349&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;finger &amp;lt;username&amp;gt;
2350&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Displays IP addresses and all the network interfaces&lt;/strong&gt;&lt;/p&gt;
2351&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ip addr show
2352&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Downloads a file from an online source&lt;/strong&gt;&lt;/p&gt;
2353&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;wget https://example.com/example.tgz
2354&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Note: If URL contains ?, &amp;amp; enclose the URL in double quotes.&lt;/p&gt;
2355&lt;p&gt;&lt;strong&gt;Compress a file with gzip&lt;/strong&gt;&lt;/p&gt;
2356&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# will not keep the original file&lt;/span&gt;
2357&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;gzip file.txt
2358&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2359&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# will keep the original file&lt;/span&gt;
2360&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;gzip --keep file.txt
2361&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Interactive disk usage analyzer&lt;/strong&gt;&lt;/p&gt;
2362&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo apt install ncdu
2363&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2364&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ncdu
2365&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ncdu &amp;lt;path/to/directory&amp;gt;
2366&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Install Node.js using the Node Version Manager&lt;/strong&gt;&lt;/p&gt;
2367&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.35.3/install.sh | bash
2368&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;source ~/.bashrc
2369&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2370&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;nvm install v13
2371&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Too long; didn&#39;t read&lt;/strong&gt;&lt;/p&gt;
2372&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;npm install -g tldr
2373&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2374&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;tldr tar
2375&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Combine all Nginx access logs to one big log file&lt;/strong&gt;&lt;/p&gt;
2376&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;zcat -f /var/log/nginx/access.log* &amp;gt; /var/log/nginx/access-all.log
2377&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Set up Redis server&lt;/strong&gt;&lt;/p&gt;
2378&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo apt install redis-server redis-tools
2379&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2380&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# check if server is running&lt;/span&gt;
2381&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo service redis status
2382&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2383&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# set and get a key value&lt;/span&gt;
2384&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;redis-cli set mykey myvalue
2385&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;redis-cli get mykey
2386&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2387&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# interactive shell&lt;/span&gt;
2388&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;redis-cli
2389&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Generate statistics of your webserver&lt;/strong&gt;&lt;/p&gt;
2390&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo apt install goaccess
2391&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2392&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# check if installed&lt;/span&gt;
2393&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;goaccess -v
2394&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2395&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# combine logs&lt;/span&gt;
2396&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;zcat -f /var/log/nginx/access.log* &amp;gt; /var/log/nginx/access-all.log
2397&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2398&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# export to single html&lt;/span&gt;
2399&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;goaccess &lt;span style=&#34;color:#a31515&#34;&gt;\
2400&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; --log-file=/var/log/nginx/access-all.log &lt;span style=&#34;color:#a31515&#34;&gt;\
2401&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; --log-format=COMBINED &lt;span style=&#34;color:#a31515&#34;&gt;\
2402&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; --exclude-ip=0.0.0.0 &lt;span style=&#34;color:#a31515&#34;&gt;\
2403&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; --ignore-crawlers &lt;span style=&#34;color:#a31515&#34;&gt;\
2404&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; --real-os &lt;span style=&#34;color:#a31515&#34;&gt;\
2405&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; --output=/var/www/html/stats.html
2406&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2407&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# cleanup afterwards&lt;/span&gt;
2408&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;rm /var/log/nginx/access-all.log
2409&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Search for a given pattern in files&lt;/strong&gt;&lt;/p&gt;
2410&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;grep -r ‘pattern’ files
2411&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Find proccess ID for a specific program&lt;/strong&gt;&lt;/p&gt;
2412&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;pgrep nginx
2413&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Print name of current/working directory&lt;/strong&gt;&lt;/p&gt;
2414&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;pwd
2415&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Creates a blank new file&lt;/strong&gt;&lt;/p&gt;
2416&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;touch newfile.txt
2417&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Displays first lines in a file&lt;/strong&gt;&lt;/p&gt;
2418&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# -n &amp;lt;x&amp;gt; presents the number of lines (10 by default)&lt;/span&gt;
2419&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;head -n 20 somefile.txt
2420&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Displays last lines in a file&lt;/strong&gt;&lt;/p&gt;
2421&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# -n &amp;lt;x&amp;gt; presents the number of lines (10 by default)&lt;/span&gt;
2422&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;tail -n 20 somefile.txt
2423&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2424&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# -f follows the changes in file (doesn&amp;#39;t closes)&lt;/span&gt;
2425&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;tail -f somefile.txt
2426&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Count lines in a file&lt;/strong&gt;&lt;/p&gt;
2427&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;wc -l somefile.txt
2428&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Find all instances of the file&lt;/strong&gt;&lt;/p&gt;
2429&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo apt install mlocate
2430&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2431&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;locate somefile.txt
2432&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Find file names that begin with ‘index’ in /home folder&lt;/strong&gt;&lt;/p&gt;
2433&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;find /home/ -name &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;index&amp;#34;&lt;/span&gt;
2434&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Find files larger than 100MB in the home folder&lt;/strong&gt;&lt;/p&gt;
2435&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;find /home -size &#43;100M
2436&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Displays block devices related information&lt;/strong&gt;&lt;/p&gt;
2437&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;lsblk
2438&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Displays free space on mounted systems&lt;/strong&gt;&lt;/p&gt;
2439&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;df -h
2440&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Displays free and used memory in the system&lt;/strong&gt;&lt;/p&gt;
2441&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;free -h
2442&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Displays all active listening ports&lt;/strong&gt;&lt;/p&gt;
2443&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo apt install net-tools
2444&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2445&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;netstat -pnltu
2446&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Kill a process violently&lt;/strong&gt;&lt;/p&gt;
2447&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;kill -9 &amp;lt;pid&amp;gt;
2448&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;List files opened by user&lt;/strong&gt;&lt;/p&gt;
2449&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;lsof -u &amp;lt;user&amp;gt;
2450&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;&lt;strong&gt;Execute &amp;quot;df -h&amp;quot;, showing periodic updates&lt;/strong&gt;&lt;/p&gt;
2451&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# -n 1 means every second&lt;/span&gt;
2452&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;watch -n 1 df -h
2453&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;</content:encoded>
2454 </item>
2455
2456
2457
2458 <item>
2459 <title>My journey from being an internet über consumer to being a full hominum again</title>
2460 <link>https://mitjafelicijan.com/from-internet-consumer-to-full-hominum-again.html</link>
2461 <pubDate>Fri, 30 Jul 2021 12:00:00 &#43;0200</pubDate>
2462 <guid>https://mitjafelicijan.com/from-internet-consumer-to-full-hominum-again.html</guid>
2463 <description>It&amp;#39;s been almost a year since I started purging all my online accounts andgoing down this rabbit hole of being almost independent of the current internetmachine.</description>
2464 <content:encoded>&lt;p&gt;It&#39;s been almost a year since I started purging all my online accounts and
2465going down this rabbit hole of being almost independent of the current internet
2466machine. Even though I initially thought that I will have problems adapting,
2467I was pleasantly surprised that the transition went so smoothly. Even better,
2468it brought many benefits to my life. Such as increased focus, less stress
2469about trivial things, etc.&lt;/p&gt;
2470&lt;p&gt;It all started with me doing small changes like unsubscribing from emails that I
2471have either subscribed to by accepting terms and conditions. Or even some more
2472malicious emails that I was getting because I was on a shared mailing list. And
2473the later ones I hate the most of all. How the hell do they keep sharing my
2474email and sending me unsolicited emails and get away with it? I have a suspicion
2475that these marketing people share an Excel file between them and keep
2476resubscribing me when they import lists into Mailchimp or similar software.&lt;/p&gt;
2477&lt;p&gt;It&#39;s fascinating to see how much crap you get subscribed to when you are not
2478paying attention. It got so bad that my primary Gmail address is a full of junk
2479and need constant monitoring and cleaning up. And because I want to have Inbox
2480Zero, this presents an additional problem for me.&lt;/p&gt;
2481&lt;p&gt;The stress that email presented for me didn&#39;t occur to me for a long time. I was
2482noticing that I was unable to go through one single hour without hysterically
2483refreshing email. And if somebody wrote me something, I needed to see it right
2484then, even though I didn&#39;t immediately reply to it. I can only describe this
2485with FOMO (fear of missing out). I have no other explanation than that. It was
2486crippling, and I was constantly context switching, which I will address further
2487down this post in more details.&lt;/p&gt;
2488&lt;p&gt;This was one of the reasons why I spawned up my personal email server, and I am
2489using it now as my primary and person email. I still have Gmail as my “junk”
2490email that I use for throw away stuff. I log in to Gmail once a week and check
2491if there are any important emails that I got, but apart from that, it&#39;s sitting
2492dormant and collecting dust.&lt;/p&gt;
2493&lt;p&gt;The more I was watching the world loose it&#39;s self with allowing anti freedom
2494things to happen to it, the more I started to realize that something has to
2495change. I don&#39;t have the power to change the world. And I also don&#39;t have a
2496grandiose opinion of myself to even think to try it. But what I can do is to not
2497subscribe to this consumer way of thinking. I will not be complicit in this. My
2498moral and ethical stances won&#39;t allow it. So, this brings us to the second part
2499of my journey.&lt;/p&gt;
2500&lt;p&gt;I was using all these 3rd party services because I was either lazy or OK with
2501the drawbacks of them. I watched these services and companies became more and
2502privacy policies and everybody is OK with accepting them, and they pray on that
2503more evil. It is evil if you sell your user&#39;s data in this manner. Nobody reads
2504flaw in human nature. I really hate the hypocrisy they manage to muster. These
2505companies prey on our laziness, and we are at fault here. Nobody else. And I
2506truly understand the reasons why we rather accept and move on, and not object
2507and have our lives a little more difficult. They have perfected this through
2508years of small changes that make us a little more dependent on them. You could
2509not convince a person to give away all his rights and data in one day. This was
2510gradual and slow. And it caught us all in surprise. When I really stopped and
2511thought about it, I felt repulsed. By really stopping and thinking about it, I
2512really mean stopping and thinking about it. Thoroughly and in depth.&lt;/p&gt;
2513&lt;p&gt;Each step I took depleted my character a bit more. Like I was trading myself bit
2514by bit without understanding what it all meant. What it meant to be a full
2515person, not divided by all this bought attention they want from me. They don&#39;t
2516just get your data, but they also take your attention away from you. They
2517scatter your and go with the divide and conquer tactic from there. And a person
2518divided is a person not fully there. Not at the moment. Not alive fully.&lt;/p&gt;
2519&lt;p&gt;I was unable to form long thoughts. Well, I thought I was. But now that I see
2520what being a full person is again, I can see that I was not at my 100% back
2521then.&lt;/p&gt;
2522&lt;p&gt;A revolt was inevitable. There was no other way of continuing my story without
2523it. Without taking back my attention, my thoughts, my time, and my privacy,
2524regardless of how too late it maybe is.&lt;/p&gt;
2525&lt;p&gt;This has nothing to do with conspiracy theories. Even less with changing the
2526world. All I wanted was to get my life back in order and not waste the energy
2527that could be spent in other, better places.&lt;/p&gt;
2528&lt;p&gt;I started reading more. I can focus now fully on things I work on. Furthermore,
2529I have the mental acuity that I never had before. My mind feels sharp. I don&#39;t
2530get angry so much. I can cherish the finer things in life now without the need
2531to interpret them intellectually. Not only that, but I have a feeling of
2532belonging again. Sense of purpose has returned with a vengeance. And I can now
2533help people without depleting myself.&lt;/p&gt;
2534&lt;p&gt;The last step so far was to finish closing all the remaining online accounts
2535that I still had. And when I was thinking what value they bring me, I wasn&#39;t
2536surprised that the answer was none. I wasn&#39;t logging in them and using them. I
2537stopped being afraid of FOMO. If somebody wants to get in contact me, they will
2538find a way. I am one search away.&lt;/p&gt;
2539&lt;p&gt;We are not beholden to anybody. Our lives are our own. So dare yourself to
2540delete Facebook, LinkedIn. To unsubscribe. Dare yourself to take your time and
2541attention back. Use that time and energy to go for a walk without thinking about
2542work. Read a book instead of reading comment on social media that you will
2543forget in an hour. Enrich your life instead of wasting it. It only requires a
2544small step. And you will feel the benefits immediately. Lose the weight of the
2545world that is crushing you without your consent.&lt;/p&gt;
2546</content:encoded>
2547 </item>
2548
2549
2550
2551 <item>
2552 <title>Simple world clock with eInk display and Raspberry Pi Zero</title>
2553 <link>https://mitjafelicijan.com/simple-world-clock-with-eiink-display-and-raspberry-pi-zero.html</link>
2554 <pubDate>Sat, 26 Jun 2021 12:00:00 &#43;0200</pubDate>
2555 <guid>https://mitjafelicijan.com/simple-world-clock-with-eiink-display-and-raspberry-pi-zero.html</guid>
2556 <description>Our team is spread across the world, from the USA all the way to Australia, sohaving some sort of world clock makes sense.</description>
2557 <content:encoded>&lt;p&gt;Our team is spread across the world, from the USA all the way to Australia, so
2558having some sort of world clock makes sense.&lt;/p&gt;
2559&lt;p&gt;Currently, I am using an extension for Gnome called &lt;a href=&#34;https://extensions.gnome.org/extension/2657/timezones-extension/&#34;&gt;Timezone
2560extension&lt;/a&gt;,
2561and it serves the purpose quite well.&lt;/p&gt;
2562&lt;p&gt;But I also have a bunch of electronics that I bought through the time, and I am
2563not using any of them, and it&#39;s time to stop hording this stuff and use it in a
2564project.&lt;/p&gt;
2565&lt;p&gt;A while ago I bought a small eInk display &lt;a href=&#34;https://shop.pimoroni.com/products/inky-phat?variant=12549254217811&#34;&gt;Inky
2566pHAT&lt;/a&gt; and I
2567have a bunch of &lt;a href=&#34;https://www.raspberrypi.org/products/raspberry-pi-zero/&#34;&gt;Raspberry Pi&#39;s
2568Zero&lt;/a&gt; lying around that
2569I really need to use.&lt;/p&gt;
2570&lt;figure&gt;
2571&lt;img src=&#34;/posts/world-clock/hardware.jpg&#34; alt=&#34;Inky pHAT, Raspberry Pi Zero&#34; /&gt;
2572&lt;/figure&gt;
2573&lt;p&gt;Since the Inky &lt;a href=&#34;https://shop.pimoroni.com/products/inky-phat?variant=12549254217811&#34;&gt;Inky
2574pHAT&lt;/a&gt; is
2575essentially a HAT, it can easily be added on top of the &lt;a href=&#34;https://www.raspberrypi.org/products/raspberry-pi-zero/&#34;&gt;Raspberry Pi
2576Zero&lt;/a&gt;.&lt;/p&gt;
2577&lt;p&gt;First, I installed the necessary software on Raspberry Pi with &lt;code&gt;pip3 install inky&lt;/code&gt;.&lt;/p&gt;
2578&lt;p&gt;And then I created a file &lt;code&gt;clock.py&lt;/code&gt; in home directory &lt;code&gt;/home/pi&lt;/code&gt;.&lt;/p&gt;
2579&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;#!/usr/bin/env python&lt;/span&gt;
2580&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# -*- coding: utf-8 -*-&lt;/span&gt;
2581&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2582&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; sys
2583&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; os
2584&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;from&lt;/span&gt; inky.auto &lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; auto
2585&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;from&lt;/span&gt; PIL &lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; Image, ImageFont, ImageDraw
2586&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;from&lt;/span&gt; font_fredoka_one &lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; FredokaOne
2587&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2588&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;clocks = [
2589&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;America/New_York&amp;#39;&lt;/span&gt;,
2590&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;Europe/Ljubljana&amp;#39;&lt;/span&gt;,
2591&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;Australia/Brisbane&amp;#39;&lt;/span&gt;,
2592&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;]
2593&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2594&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;board = auto()
2595&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;board.set_border(board.WHITE)
2596&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;board.rotation = 90
2597&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2598&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;img = Image.new(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;P&amp;#39;&lt;/span&gt;, (board.WIDTH, board.HEIGHT))
2599&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;draw = ImageDraw.Draw(img)
2600&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2601&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;big_font = ImageFont.truetype(FredokaOne, 18)
2602&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;small_font = ImageFont.truetype(FredokaOne, 13)
2603&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2604&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;x = board.WIDTH / 3
2605&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;y = board.HEIGHT / 3
2606&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2607&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;idx = 1
2608&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; clock &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; clocks:
2609&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; ctime = os.popen(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;TZ=&amp;#34;&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;{}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34; date &#43;&amp;#34;&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%a&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;,%H:%M&amp;#34;&amp;#39;&lt;/span&gt;.format(clock))
2610&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; ctime = ctime.read().strip().split(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;,&amp;#39;&lt;/span&gt;)
2611&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; city = clock.split(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;/&amp;#39;&lt;/span&gt;)[1].replace(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;_&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39; &amp;#39;&lt;/span&gt;)
2612&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2613&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; draw.text((15, (idx*y)-y&#43;10), city, fill=board.BLACK, font=small_font)
2614&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; draw.text((110, (idx*y)-y&#43;7), str(ctime[0]), fill=board.BLACK, font=big_font)
2615&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; draw.text((155, (idx*y)-y&#43;7), str(ctime[1]), fill=board.BLACK, font=big_font)
2616&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2617&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; idx &#43;= 1
2618&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2619&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;board.set_image(img)
2620&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;board.show()
2621&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;And because eInk displays are rather slow to refresh and the clock requires
2622refreshing only once a minute, this can be done through cronjob.&lt;/p&gt;
2623&lt;p&gt;Before we add this job to cron we need to make &lt;code&gt;clock.py&lt;/code&gt; executable with &lt;code&gt;chmod &#43;x clock.py&lt;/code&gt;.&lt;/p&gt;
2624&lt;p&gt;Then we add a cronjob with &lt;code&gt;crontab -e&lt;/code&gt;.&lt;/p&gt;
2625&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;* * * * * /home/pi/clock.py
2626&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;So, we end up with a result like this.&lt;/p&gt;
2627&lt;figure&gt;
2628&lt;img src=&#34;/posts/world-clock/world-clock.jpg&#34; alt=&#34;World Clock&#34; /&gt;
2629&lt;/figure&gt;
2630&lt;p&gt;And for the enclosure that can be 3D printed, but I haven&#39;t yet something like
2631this can be used.&lt;/p&gt;
2632&lt;iframe id=&#34;vs_iframe&#34; src=&#34;https://www.viewstl.com/?embedded&amp;url=https%3A%2F%2Fmitjafelicijan.com%2Fposts%2Fworld-clock%2Fenclosure.stl&amp;color=gray&amp;bgcolor=white&amp;edges=no&amp;orientation=front&amp;noborder=no&#34; style=&#34;border:0;margin:0;width:100%;height:400px;&#34;&gt;&lt;/iframe&gt;
2633&lt;p&gt;You can download my &lt;a href=&#34;/posts/world-clock/enclosure.stl&#34;&gt;STL file for the enclosure
2634here&lt;/a&gt;, but make sure that dimensions make
2635sense and also opening for USB port should be added or just use a drill and some
2636hot glue to make it stick in the enclosure.&lt;/p&gt;
2637</content:encoded>
2638 </item>
2639
2640
2641
2642 <item>
2643 <title>Using GoAccess with Nginx to replace Google Analytics</title>
2644 <link>https://mitjafelicijan.com/using-goaccess-with-nginx-to-replace-google-analytics.html</link>
2645 <pubDate>Mon, 25 Jan 2021 12:00:00 &#43;0200</pubDate>
2646 <guid>https://mitjafelicijan.com/using-goaccess-with-nginx-to-replace-google-analytics.html</guid>
2647 <description>IntroductionI know!</description>
2648 <content:encoded>&lt;h2 id=&#34;introduction&#34;&gt;Introduction&lt;/h2&gt;
2649&lt;p&gt;I know! You cannot simply replace Google Analytics with parsing access logs and
2650displaying a couple of charts. But to be honest, I actually never used Google
2651Analytics to the fullest extent and was usually interested in seeing page hits
2652and which pages were visited most often.&lt;/p&gt;
2653&lt;p&gt;I recently moved my blog from Firebase to a VPS and also decided to remove
2654Google Analytics tracking code from the site since its quite malicious and
2655tracks users across other pages also and is creating a profile of a user, and
2656I&#39;ve had it. But I also need some insight of what is happening on a server and
2657which content is being read the most etc.&lt;/p&gt;
2658&lt;p&gt;I have looked at many existing solutions like:&lt;/p&gt;
2659&lt;ul&gt;
2660&lt;li&gt;&lt;a href=&#34;https://umami.is/&#34;&gt;Umami&lt;/a&gt;&lt;/li&gt;
2661&lt;li&gt;&lt;a href=&#34;https://github.com/sheshbabu/freshlytics&#34;&gt;Freshlytics&lt;/a&gt;&lt;/li&gt;
2662&lt;li&gt;&lt;a href=&#34;https://matomo.org/&#34;&gt;Matomo&lt;/a&gt;&lt;/li&gt;
2663&lt;/ul&gt;
2664&lt;p&gt;But the more I looked at them the more I noticed that I am replacing one evil
2665with another one. Don&#39;t get me wrong. Some of these solutions are absolutely
2666fantastic but would require installation of databases and something like PHP or
2667Node. And I was not ready to put those things on my fresh server. Also having
2668Docker installed is out of the question.&lt;/p&gt;
2669&lt;h2 id=&#34;opting-for-log-parsing&#34;&gt;Opting for log parsing&lt;/h2&gt;
2670&lt;p&gt;So, I defaulted to parsing already existing logs and generating HTML reports
2671from this data.&lt;/p&gt;
2672&lt;p&gt;I found this amazing software &lt;a href=&#34;https://goaccess.io/&#34;&gt;GoAccess&lt;/a&gt; which provides
2673all the functionalities I need, and it&#39;s a single binary. Written in Go.&lt;/p&gt;
2674&lt;p&gt;GoAccess can be used in two different modes.&lt;/p&gt;
2675&lt;figure&gt;
2676&lt;img src=&#34;/posts/goaccess/goaccess-dash-term.png&#34; alt=&#34;GoAccess Terminal&#34; /&gt;
2677&lt;/figure&gt;
2678&lt;p&gt;&lt;em&gt;Running in a terminal&lt;/em&gt;&lt;/p&gt;
2679&lt;figure&gt;
2680&lt;img src=&#34;/posts/goaccess/goaccess-dash-html.png&#34; alt=&#34;GoAccess HTML&#34; /&gt;
2681&lt;/figure&gt;
2682&lt;p&gt;&lt;em&gt;Running in a browser&lt;/em&gt;&lt;/p&gt;
2683&lt;p&gt;I, however, need this to run in a browser. So, the second option is the way to
2684go. The Idea is to periodically run cronjob and export this report into a folder
2685that gets then server by Nginx behind a Basic authentication.&lt;/p&gt;
2686&lt;h2 id=&#34;getting-nginx-ready&#34;&gt;Getting Nginx ready&lt;/h2&gt;
2687&lt;p&gt;I choose Ubuntu on &lt;a href=&#34;https://www.digitalocean.com/&#34;&gt;DigitalOcean&lt;/a&gt;. First I
2688installed &lt;a href=&#34;https://nginx.org/en/&#34;&gt;Nginx&lt;/a&gt;, and
2689&lt;a href=&#34;https://letsencrypt.org/getting-started/&#34;&gt;Letsencrypt&lt;/a&gt; certbot and all the
2690necessary dependencies.&lt;/p&gt;
2691&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# log in as root user&lt;/span&gt;
2692&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo su -
2693&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2694&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# first let&amp;#39;s update the system&lt;/span&gt;
2695&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;apt update &amp;amp;&amp;amp; apt upgrade -y
2696&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2697&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# let&amp;#39;s install&lt;/span&gt;
2698&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;apt install nginx certbot python3-certbot-nginx apache2-utils
2699&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;After all this is installed we can create a new configuration for a statistics.
2700Stats will be available at &lt;code&gt;stats.domain.com&lt;/code&gt;.&lt;/p&gt;
2701&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# creates directory where html will be hosted&lt;/span&gt;
2702&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;mkdir -p /var/www/html/stats.domain.com
2703&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2704&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;cp /etc/nginx/sites-available/default /etc/nginx/sites-available/stats.domain.com
2705&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;nano /etc/nginx/sites-available/stats.domain.com
2706&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;server&lt;/span&gt; {
2707&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;root&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;/var/www/html/stats.domain.com&lt;/span&gt;;
2708&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;server_name&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;stats.domain.com&lt;/span&gt;;
2709&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2710&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;index&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;index.html&lt;/span&gt;;
2711&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;location&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;/&lt;/span&gt; {
2712&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;try_files&lt;/span&gt; $uri $uri/ =404;
2713&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
2714&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
2715&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Now we check if the configuration is ok. We can do this with &lt;code&gt;nginx -t&lt;/code&gt;. If all
2716is ok, we can restart Nginx with &lt;code&gt;service nginx restart&lt;/code&gt;.&lt;/p&gt;
2717&lt;p&gt;After all that you should add A record for this domain that points to IP of a
2718droplet.&lt;/p&gt;
2719&lt;p&gt;Before enabling SSL you should test if DNS records have propagated with &lt;code&gt;curl stats.domain.com&lt;/code&gt;.&lt;/p&gt;
2720&lt;p&gt;Now, it&#39;s time to provision TLS certificate. To achieve this, you execute
2721command &lt;code&gt;certbot --nginx&lt;/code&gt;. Follow the wizard and when you are asked about
2722redirection always choose 2 (always redirect to HTTPS).&lt;/p&gt;
2723&lt;p&gt;When this is done you can visit &lt;a href=&#34;https://stats.domain.com&#34;&gt;https://stats.domain.com&lt;/a&gt; and you should get 404
2724not found error which is correct.&lt;/p&gt;
2725&lt;h2 id=&#34;getting-goaccess-ready&#34;&gt;Getting GoAccess ready&lt;/h2&gt;
2726&lt;p&gt;If you are using Debian like system GoAccess should be available in repository.
2727Otherwise refer to the official website.&lt;/p&gt;
2728&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;apt install goaccess
2729&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;To enable Geo location we also need one additiona thing.&lt;/p&gt;
2730&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;cd /var/www/html/stats.stats.com
2731&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;wget https://github.com/P3TERX/GeoLite.mmdb/raw/download/GeoLite2-City.mmdb
2732&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Now we create a shell script that will be executed every 10 minutes.&lt;/p&gt;
2733&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;nano /var/www/html/stats.domain.com/generate-stats.sh
2734&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Contents of this file should look like this.&lt;/p&gt;
2735&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;#!/bin/sh
2736&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;&lt;/span&gt;
2737&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;zcat -f /var/log/nginx/access.log* &amp;gt; /var/log/nginx/access-all.log
2738&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2739&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;goaccess &lt;span style=&#34;color:#a31515&#34;&gt;\
2740&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; --log-file=/var/log/nginx/access-all.log &lt;span style=&#34;color:#a31515&#34;&gt;\
2741&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; --log-format=COMBINED &lt;span style=&#34;color:#a31515&#34;&gt;\
2742&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; --exclude-ip=0.0.0.0 &lt;span style=&#34;color:#a31515&#34;&gt;\
2743&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; --geoip-database=/var/www/html/stats.domain.com/GeoLite2-City.mmdb &lt;span style=&#34;color:#a31515&#34;&gt;\
2744&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; --ignore-crawlers &lt;span style=&#34;color:#a31515&#34;&gt;\
2745&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; --real-os &lt;span style=&#34;color:#a31515&#34;&gt;\
2746&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; --output=/var/www/html/stats.domain.com/index.html
2747&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2748&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;rm /var/log/nginx/access-all.log
2749&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Because after a while nginx creates multiple files with access logs we use
2750&lt;a href=&#34;https://linux.die.net/man/1/zcat&#34;&gt;&lt;code&gt;zcat&lt;/code&gt;&lt;/a&gt; to extract Gziped contents and create
2751a file that has all the access logs. After this file is used we delete it.&lt;/p&gt;
2752&lt;p&gt;If you want to exclude your home IP&#39;s result look at the &lt;code&gt;--exclude-ip&lt;/code&gt; option
2753in script and instead of &lt;code&gt;0.0.0.0&lt;/code&gt; add your own home IP address. You can find
2754your home IP by executing &lt;code&gt;curl ifconfig.me&lt;/code&gt; from your local machine and NOT
2755from the droplet.&lt;/p&gt;
2756&lt;p&gt;Test the script by executing &lt;code&gt;sh /var/www/html/stats.domain.com/generate-stats.sh&lt;/code&gt; and then checking
2757&lt;code&gt;https://stats.domain.com&lt;/code&gt;. If you can see stats instead of 404 than you are
2758set.&lt;/p&gt;
2759&lt;p&gt;It&#39;s time to add this script to cron with &lt;code&gt;cron -e&lt;/code&gt;.&lt;/p&gt;
2760&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;*/10 * * * * sh /&lt;span style=&#34;color:#00f&#34;&gt;var&lt;/span&gt;/www/html/stats.domain.com/generate-stats.sh
2761&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;securing-with-basic-authentication&#34;&gt;Securing with Basic authentication&lt;/h2&gt;
2762&lt;p&gt;You probably don&#39;t want stats to be publicly available, so we should create a
2763user and a password for Basic authentication.&lt;/p&gt;
2764&lt;p&gt;First we create a password for a user &lt;code&gt;stats&lt;/code&gt; with &lt;code&gt;htpasswd -c /etc/nginx/.htpasswd stats&lt;/code&gt;.&lt;/p&gt;
2765&lt;p&gt;Now we update config file with &lt;code&gt;nano /etc/nginx/sites-available/stats.domain.com&lt;/code&gt;. You probably noticed that the
2766file looks a bit different from before. This is because &lt;code&gt;certbot&lt;/code&gt; added
2767additional rules for SSL.&lt;/p&gt;
2768&lt;p&gt;Your location portion the config file should now look like. You should add
2769&lt;code&gt;auth_basic&lt;/code&gt; and &lt;code&gt;auth_basic_user_file&lt;/code&gt; lines to the file.&lt;/p&gt;
2770&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;location&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;/&lt;/span&gt; {
2771&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;try_files&lt;/span&gt; $uri $uri/ =404;
2772&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;auth_basic&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Private&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;Property&amp;#34;&lt;/span&gt;;
2773&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;auth_basic_user_file&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;/etc/nginx/.htpasswd&lt;/span&gt;;
2774&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
2775&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Test if config is still ok with &lt;code&gt;nginx -t&lt;/code&gt; and if it is you can restart Nginx
2776with &lt;code&gt;service nginx restart&lt;/code&gt;.&lt;/p&gt;
2777&lt;p&gt;If you now visit &lt;code&gt;https://stats.domain.com&lt;/code&gt; you should be prompted for username
2778and password. If not, try reopening your browser.&lt;/p&gt;
2779&lt;p&gt;That is all. You now have analytics for your server that gets refreshed every 10
2780minutes.&lt;/p&gt;
2781</content:encoded>
2782 </item>
2783
2784
2785
2786 <item>
2787 <title>Replacing Dropbox in favor of DigitalOcean spaces</title>
2788 <link>https://mitjafelicijan.com/replacing-dropbox-in-favor-of-digitalocean-spaces.html</link>
2789 <pubDate>Sun, 24 Jan 2021 12:00:00 &#43;0200</pubDate>
2790 <guid>https://mitjafelicijan.com/replacing-dropbox-in-favor-of-digitalocean-spaces.html</guid>
2791 <description>A few months ago I experimented with DigitalOcean spaces as my backup solutionthat could replace Dropboxeventually.</description>
2792 <content:encoded>&lt;p&gt;A few months ago I experimented with DigitalOcean spaces as my backup solution
2793that could &lt;a href=&#34;/digitalocean-spaces-to-sync-between-computers.html&#34;&gt;replace Dropbox
2794eventually&lt;/a&gt;. That solution
2795worked quite nicely, and I was amazed how smashing together a couple of existing
2796solutions would work this fine.&lt;/p&gt;
2797&lt;p&gt;I have been running that solution in the background for a couple of months now
2798and kind of forgot about it. But recent developments around deplatforming and
2799having us people hostages of technology and big companies speed up my goals to
2800become less dependent on
2801&lt;a href=&#34;https://edition.cnn.com/2020/12/17/tech/google-antitrust-lawsuit/index.html&#34;&gt;Google&lt;/a&gt;,
2802&lt;a href=&#34;https://www.pcworld.com/article/2048680/dropbox-takes-a-peek-at-files.html&#34;&gt;Dropbox&lt;/a&gt;
2803etc and take back some control.&lt;/p&gt;
2804&lt;p&gt;I am not a conspiracy theory nut, but to be honest, what these companies are
2805doing lately is out of control. It is a matter of principle at this point. I
2806have almost completely degoogled my life all the way from ditching Gmail,
2807YouTube and most of the services surrounding Google. And I must tell you, I feel
2808so good. I haven&#39;t felt this way for a long time.&lt;/p&gt;
2809&lt;p&gt;&lt;strong&gt;Anyways. Let&#39;s get to the meat of things.&lt;/strong&gt;&lt;/p&gt;
2810&lt;p&gt;Before you continue you should read my post about &lt;a href=&#34;/digitalocean-spaces-to-sync-between-computers.html&#34;&gt;syncing to
2811Dropbox&lt;/a&gt;.&lt;/p&gt;
2812&lt;blockquote&gt;
2813&lt;p&gt;Also to note, I am using Linux on my machine with Gnome desktop environment.
2814This should work on MacOS too. To use this on Windows I suggest using
2815&lt;a href=&#34;https://docs.microsoft.com/en-us/windows/wsl/install-win10&#34;&gt;Subsystem for Linux&lt;/a&gt;
2816or &lt;a href=&#34;https://www.cygwin.com/&#34;&gt;Cygwin&lt;/a&gt;.&lt;/p&gt;
2817&lt;/blockquote&gt;
2818&lt;h2 id=&#34;folder-structure&#34;&gt;Folder structure&lt;/h2&gt;
2819&lt;p&gt;I liked structure from Dropbox. One folder where everything is located and
2820synced. So, that&#39;s why adopted this also for my sync setup.&lt;/p&gt;
2821&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;&#34;&gt;~&lt;/span&gt;/Vault
2822&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;&#34;&gt;↳&lt;/span&gt; backup
2823&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;&#34;&gt;↳&lt;/span&gt; bin
2824&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;&#34;&gt;↳&lt;/span&gt; documents
2825&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;&#34;&gt;↳&lt;/span&gt; projects
2826&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;All of my code is located in &lt;code&gt;~/Vault/projects&lt;/code&gt; folder. And most of the projects
2827are Git repositories. I do not use this sync method for backup per see but in
2828case I reinstall my machine I can easily recreate all the important folder
2829structure with one quick command. No external drives needed that can fail etc.&lt;/p&gt;
2830&lt;h2 id=&#34;sync-script&#34;&gt;Sync script&lt;/h2&gt;
2831&lt;p&gt;My sync script is located in &lt;code&gt;~/Vault/bin/vault-backup.sh&lt;/code&gt;&lt;/p&gt;
2832&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;#!/bin/bash
2833&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;&lt;/span&gt;
2834&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# dconf load /com/gexperts/Tilix/ &amp;lt; tilix.dconf&lt;/span&gt;
2835&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# 0 2 * * * sh ~/Vault/bin/vault-backup.sh&lt;/span&gt;
2836&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2837&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;cd ~/Vault/backup/dotfiles
2838&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2839&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;MACHINE=&lt;span style=&#34;color:#00f&#34;&gt;$(&lt;/span&gt;whoami&lt;span style=&#34;color:#00f&#34;&gt;)&lt;/span&gt;@&lt;span style=&#34;color:#00f&#34;&gt;$(&lt;/span&gt;hostname&lt;span style=&#34;color:#00f&#34;&gt;)&lt;/span&gt;
2840&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;mkdir -p $MACHINE
2841&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;cd $MACHINE
2842&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2843&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;cp ~/.config/VSCodium/User/settings.json settings.json
2844&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;cp ~/.s3cfg s3cfg
2845&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;cp ~/.bash_extended bash_extended
2846&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;cp ~/.ssh ssh -rf
2847&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2848&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;codium --list-extensions &amp;gt; vscode-extension.txt
2849&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;dconf dump /com/gexperts/Tilix/ &amp;gt; tilix.dconf
2850&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2851&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;cd ~/Vault
2852&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;s3cmd sync --delete-removed --exclude &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;node_modules/*&amp;#39;&lt;/span&gt; --exclude &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;.git/*&amp;#39;&lt;/span&gt; --exclude &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;.venv/*&amp;#39;&lt;/span&gt; ./ s3://bucket-name/backup/
2853&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2854&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;echo &lt;span style=&#34;color:#a31515&#34;&gt;`&lt;/span&gt;date &#43;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;%D %T&amp;#34;&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;`&lt;/span&gt; &amp;gt;&amp;gt; ~/.vault.log
2855&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
2856&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;notify-send &lt;span style=&#34;color:#a31515&#34;&gt;\
2857&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; -u normal &lt;span style=&#34;color:#a31515&#34;&gt;\
2858&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; -i /usr/share/icons/Adwaita/96x96/status/security-medium-symbolic.symbolic.png &lt;span style=&#34;color:#a31515&#34;&gt;\
2859&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Vault sync succeded at `date &#43;&amp;#34;&lt;/span&gt;%D %T&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;`&amp;#34;&lt;/span&gt;
2860&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;This script also backups some of the dotfiles I use and sends notification to
2861Gnome notification center. It is a straightforward solution. Nothing special
2862going on.&lt;/p&gt;
2863&lt;blockquote&gt;
2864&lt;p&gt;One obvious benefit of this is that I can omit syncing Node&#39;s &lt;code&gt;node_modules&lt;/code&gt;
2865or Python&#39;s &lt;code&gt;.venv&lt;/code&gt; and &lt;code&gt;.git&lt;/code&gt; folders.&lt;/p&gt;
2866&lt;/blockquote&gt;
2867&lt;p&gt;You can use this script in a combination with &lt;a href=&#34;https://en.wikipedia.org/wiki/Cron&#34;&gt;Cron&lt;/a&gt;.&lt;/p&gt;
2868&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;0 2 * * * sh ~/Vault/bin/vault-backup.sh
2869&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;When you start syncing your local stuff with a remote server you can review your
2870items on DigitalOcean.&lt;/p&gt;
2871&lt;figure&gt;
2872&lt;img src=&#34;/posts/dropbox-sync/dropbox-spaces.png&#34; alt=&#34;Dropbox Spaces&#34; /&gt;
2873&lt;/figure&gt;
2874&lt;p&gt;I have been using this script now for quite some time, and it&#39;s working
2875flawlessly. I also uninstalled Dropbox and stopped using it completely.&lt;/p&gt;
2876&lt;p&gt;All I need to do is write a Bash script that does the reverse and downloads from
2877remote server to local folder. This could be another post.&lt;/p&gt;
2878</content:encoded>
2879 </item>
2880
2881
2882
2883 <item>
2884 <title>Using Digitalocean Spaces to sync between computers</title>
2885 <link>https://mitjafelicijan.com/digitalocean-spaces-to-sync-between-computers.html</link>
2886 <pubDate>Wed, 09 Sep 2020 12:00:00 &#43;0200</pubDate>
2887 <guid>https://mitjafelicijan.com/digitalocean-spaces-to-sync-between-computers.html</guid>
2888 <description>I&amp;#39;ve been using Dropbox for probably 10&#43; yearsnow and I-ve became so used to it that it runs in the background that I don&amp;#39;teven imagine a world without it.</description>
2889 <content:encoded>&lt;p&gt;I&#39;ve been using &lt;a href=&#34;https://www.dropbox.com/&#34;&gt;Dropbox&lt;/a&gt; for probably &lt;strong&gt;10&#43; years&lt;/strong&gt;
2890now and I-ve became so used to it that it runs in the background that I don&#39;t
2891even imagine a world without it. But it&#39;s not without problems.&lt;/p&gt;
2892&lt;p&gt;At first I had problems with &lt;code&gt;.venv&lt;/code&gt; environments for Python and the only
2893solution for excluding synchronization for this folder was to manually exclude a
2894specific folder which is not really scalable. FYI, my whole project folder is
2895synced on &lt;a href=&#34;https://www.dropbox.com/&#34;&gt;Dropbox&lt;/a&gt;. This of course introduced a lot
2896of syncing of files and folders that are not needed or even break things on
2897other machines. In the case of &lt;strong&gt;Python&lt;/strong&gt;, I couldn&#39;t use that on my second
2898machine. I needed to delete &lt;code&gt;.venv&lt;/code&gt; folder and pip it again which synced files
2899again to the main machine. This was very frustrating. &lt;strong&gt;Nodejs&lt;/strong&gt; handles this
2900much nicer and I can just run the scripts without deleting &lt;code&gt;node_modules&lt;/code&gt; again
2901and reinstalling. However, &lt;code&gt;node_modules&lt;/code&gt; is a beast of its own. It creates so
2902many files that OS has a problem counting them when you check the folder
2903contents for size.&lt;/p&gt;
2904&lt;p&gt;I wanted something similar to Dropbox. I could without the instant syncing but
2905it would need to be fast and had the option for me to exclude folders like
2906&lt;code&gt;node_modules, .venv, .git&lt;/code&gt; and folders like that.&lt;/p&gt;
2907&lt;p&gt;I went on a hunt for an alternative to &lt;a href=&#34;https://www.dropbox.com/&#34;&gt;Dropbox&lt;/a&gt;
2908and found:&lt;/p&gt;
2909&lt;ul&gt;
2910&lt;li&gt;&lt;a href=&#34;https://tresorit.com/&#34;&gt;Tresorit&lt;/a&gt;&lt;/li&gt;
2911&lt;li&gt;&lt;a href=&#34;https://sync.com&#34;&gt;Sync.com&lt;/a&gt;&lt;/li&gt;
2912&lt;li&gt;&lt;a href=&#34;https://www.box.com/&#34;&gt;Box&lt;/a&gt;&lt;/li&gt;
2913&lt;/ul&gt;
2914&lt;p&gt;You know, the usual list of suspects. I didn&#39;t include &lt;a href=&#34;https://drive.google.com&#34;&gt;Google
2915drive&lt;/a&gt; or &lt;a href=&#34;https://onedrive.live.com/&#34;&gt;One drive&lt;/a&gt;
2916since they are even more draconian than Dropbox.&lt;/p&gt;
2917&lt;blockquote&gt;
2918&lt;p&gt;All this does not stem from me being paranoid but recently these companies
2919have became more and more aggressive and they keep violating our privacy when
2920they share our data with 3rd party services. It is getting out of control.&lt;/p&gt;
2921&lt;/blockquote&gt;
2922&lt;p&gt;So, my main problem was still there. No way of excluding a specific folder from
2923syncing. And before we go into &amp;quot;&lt;em&gt;But you have git, isn&#39;t that enough?&lt;/em&gt;&amp;quot;, I must
2924say, that many of the files (PDFs, spreadsheets, etc) I have in a &lt;code&gt;git&lt;/code&gt; repo
2925don&#39;t get pushed upstream to Git and I still want to have them synced across my
2926computers.&lt;/p&gt;
2927&lt;p&gt;I initially wanted to use &lt;a href=&#34;https://linux.die.net/man/1/rsync&#34;&gt;rsync&lt;/a&gt; but I would
2928need to then have a remote VPS or transfer between my computers directly. I
2929wanted a solution where all my files could be accessible to me without my
2930machine.&lt;/p&gt;
2931&lt;blockquote&gt;
2932&lt;p&gt;&lt;strong&gt;WARNING: This solution will cost you money!&lt;/strong&gt; DigitalOcean Spaces are $5 per
2933month and there are some bandwidth limitations and if you go beyond that you get
2934billed additionally.&lt;/p&gt;
2935&lt;/blockquote&gt;
2936&lt;p&gt;Then I remembered that I could use something like
2937&lt;a href=&#34;https://en.wikipedia.org/wiki/Amazon_S3&#34;&gt;S3&lt;/a&gt; since it has versioning and is
2938fully managed. I didn&#39;t want to go down the AWS rabbit hole with this so I
2939choose &lt;a href=&#34;https://www.digitalocean.com/products/spaces/&#34;&gt;DigitalOcean Spaces&lt;/a&gt;.&lt;/p&gt;
2940&lt;p&gt;Then I needed a command-line tool to sync between source and target. I found
2941this nice tool &lt;a href=&#34;https://s3tools.org/s3cmd&#34;&gt;s3cmd&lt;/a&gt; and it is in the Ubuntu
2942repositories.&lt;/p&gt;
2943&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo apt install s3cmd
2944&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;After installation will I create a new Space bucket on DigitalOcean. Remember
2945the zone you will choose because you will need it when you will configure
2946&lt;code&gt;s3cmd&lt;/code&gt;.&lt;/p&gt;
2947&lt;p&gt;Then I visited &lt;a href=&#34;https://cloud.digitalocean.com/account/api/tokens&#34;&gt;Digitalocean Applications &amp;amp;
2948API&lt;/a&gt; and generated &lt;strong&gt;Spaces
2949access keys&lt;/strong&gt;. Save both key and secret somewhere safe because when you will
2950leave the page secret will not be available anymore to you and you will need to
2951re-generate it.&lt;/p&gt;
2952&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# enter your key and secret and correct endpoint&lt;/span&gt;
2953&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# my endpoint is ams3.digitaloceanspaces.com because&lt;/span&gt;
2954&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# I created my bucket in Amsterdam regiin&lt;/span&gt;
2955&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;s3cmd --configure
2956&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;After that I played around with options for &lt;code&gt;s3cmd&lt;/code&gt; and got to the following
2957command.&lt;/p&gt;
2958&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# I executed this command from my projects folder&lt;/span&gt;
2959&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;cd projects
2960&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;s3cmd sync --delete-removed --exclude &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;node_modules/*&amp;#39;&lt;/span&gt; --exclude &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;.git/*&amp;#39;&lt;/span&gt; --exclude &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;.venv/*&amp;#39;&lt;/span&gt; ./ s3://my-bucket-name/projects/
2961&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;When syncing int he other direction you will need to change the order of the
2962&lt;code&gt;SOURCE&lt;/code&gt; and &lt;code&gt;TARGET&lt;/code&gt; to &lt;code&gt;s3://my-bucket-name/projects/&lt;/code&gt; and &lt;code&gt;./&lt;/code&gt;.&lt;/p&gt;
2963&lt;blockquote&gt;
2964&lt;p&gt;Be sure that all the paths have trailing slash so that sync knows that this
2965are directories.&lt;/p&gt;
2966&lt;/blockquote&gt;
2967&lt;p&gt;I am planning to implement some sort of a &lt;code&gt;.ignore&lt;/code&gt; file that will enable me to
2968have a project-specific exclude options.&lt;/p&gt;
2969&lt;p&gt;I am currently running this every hour as a cronjob which is perfectly fine for
2970now when I am testing how this whole thing works and how it all will turn out.&lt;/p&gt;
2971&lt;p&gt;I have also created a small Gnome extension which is still very unstable, but
2972when/if this whole experiment pays of I will share on Github.&lt;/p&gt;
2973</content:encoded>
2974 </item>
2975
2976
2977
2978 <item>
2979 <title>Fix bind warning in .profile on login in Ubuntu</title>
2980 <link>https://mitjafelicijan.com/bind-warning-on-login-in-ubuntu.html</link>
2981 <pubDate>Tue, 08 Sep 2020 12:00:00 &#43;0200</pubDate>
2982 <guid>https://mitjafelicijan.com/bind-warning-on-login-in-ubuntu.html</guid>
2983 <description>Recently I moved back to bash as mydefault shell.</description>
2984 <content:encoded>&lt;p&gt;Recently I moved back to &lt;a href=&#34;https://www.gnu.org/software/bash/&#34;&gt;bash&lt;/a&gt; as my
2985default shell. I was previously using &lt;a href=&#34;https://fishshell.com/&#34;&gt;fish&lt;/a&gt; and got
2986used to the cool features it has. But, regardless of that, I wanted to move to a
2987more standard shell because I was hopping back and forth with exporting
2988variables and stuff like that which got pretty annoying.&lt;/p&gt;
2989&lt;p&gt;So I embarked on a mission to make &lt;a href=&#34;https://www.gnu.org/software/bash/&#34;&gt;bash&lt;/a&gt;
2990more like &lt;a href=&#34;https://fishshell.com/&#34;&gt;fish&lt;/a&gt; and in the process found that I really
2991missed autosuggest with TAB on changing directories.&lt;/p&gt;
2992&lt;p&gt;I found a nice alternative that emulates &lt;a href=&#34;http://zsh.sourceforge.net/&#34;&gt;zsh&lt;/a&gt; like
2993autosuggestion and autocomplete so I added the following to my &lt;code&gt;.bashrc&lt;/code&gt; file.&lt;/p&gt;
2994&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;bind &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;TAB:menu-complete&amp;#34;&lt;/span&gt;
2995&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;bind &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;set show-all-if-ambiguous on&amp;#34;&lt;/span&gt;
2996&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;bind &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;set completion-ignore-case on&amp;#34;&lt;/span&gt;
2997&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;bind &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;set menu-complete-display-prefix on&amp;#34;&lt;/span&gt;
2998&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;bind &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;&amp;#34;\e[Z&amp;#34;:menu-complete-backward&amp;#39;&lt;/span&gt;
2999&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;I haven&#39;t noticed anything wrong with this and all was working fine until I
3000restarted my machine and then I got this error.&lt;/p&gt;
3001&lt;figure&gt;
3002&lt;img src=&#34;/posts/profile-bind-error/error.jpg&#34; alt=&#34;Profile bind error&#34; /&gt;
3003&lt;/figure&gt;
3004&lt;p&gt;When I pressed OK, I got into the &lt;a href=&#34;https://wiki.gnome.org/Projects/GnomeShell&#34;&gt;Gnome
3005shell&lt;/a&gt; and all was working fine, but
3006the error was still bugging me. I started looking for the reason why this is
3007happening and found a solution to this error on &lt;a href=&#34;https://superuser.com/a/892682&#34;&gt;Remote SSH Commands - bash bind
3008warning: line editing not enabled&lt;/a&gt;.&lt;/p&gt;
3009&lt;p&gt;So I added a simple &lt;code&gt;if [ -t 1 ]&lt;/code&gt; around &lt;code&gt;bind&lt;/code&gt; statements to avoid running
3010commands that presume the session is interactive when it isn&#39;t.&lt;/p&gt;
3011&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; [ -t 1 ]; &lt;span style=&#34;color:#00f&#34;&gt;then&lt;/span&gt;
3012&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; bind &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;TAB:menu-complete&amp;#34;&lt;/span&gt;
3013&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; bind &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;set show-all-if-ambiguous on&amp;#34;&lt;/span&gt;
3014&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; bind &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;set completion-ignore-case on&amp;#34;&lt;/span&gt;
3015&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; bind &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;set menu-complete-display-prefix on&amp;#34;&lt;/span&gt;
3016&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; bind &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;&amp;#34;\e[Z&amp;#34;:menu-complete-backward&amp;#39;&lt;/span&gt;
3017&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;fi&lt;/span&gt;
3018&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;After logging out and back in the problem was gone.&lt;/p&gt;
3019</content:encoded>
3020 </item>
3021
3022
3023
3024 <item>
3025 <title>Getting started with MicroPython and ESP8266</title>
3026 <link>https://mitjafelicijan.com/esp8266-and-micropython-guide.html</link>
3027 <pubDate>Sun, 06 Sep 2020 12:00:00 &#43;0200</pubDate>
3028 <guid>https://mitjafelicijan.com/esp8266-and-micropython-guide.html</guid>
3029 <description>IntroductionA while ago I bought someESP8266 andESP32 dev boards to playaround with and I finally found a project to try it out.</description>
3030 <content:encoded>&lt;h2 id=&#34;introduction&#34;&gt;Introduction&lt;/h2&gt;
3031&lt;p&gt;A while ago I bought some
3032&lt;a href=&#34;https://www.espressif.com/en/products/socs/esp8266&#34;&gt;ESP8266&lt;/a&gt; and
3033&lt;a href=&#34;https://www.espressif.com/en/products/socs/esp32&#34;&gt;ESP32&lt;/a&gt; dev boards to play
3034around with and I finally found a project to try it out.&lt;/p&gt;
3035&lt;p&gt;For my project, I used &lt;a href=&#34;https://www.espressif.com/en/products/socs/esp32&#34;&gt;ESP32&lt;/a&gt;
3036but I could easily choose
3037&lt;a href=&#34;https://www.espressif.com/en/products/socs/esp8266&#34;&gt;ESP8266&lt;/a&gt;. This guide
3038contains which tools I use and how I prepared my workspace to code for
3039&lt;a href=&#34;https://www.espressif.com/en/products/socs/esp8266&#34;&gt;ESP8266&lt;/a&gt;.&lt;/p&gt;
3040&lt;figure&gt;
3041&lt;img src=&#34;/posts/esp8366-micropython/boards.jpg&#34; alt=&#34;ESP8266 and ESP32 boards&#34; /&gt;
3042&lt;/figure&gt;
3043&lt;p&gt;This guide covers:&lt;/p&gt;
3044&lt;ul&gt;
3045&lt;li&gt;flashing SOC&lt;/li&gt;
3046&lt;li&gt;install proper tooling&lt;/li&gt;
3047&lt;li&gt;deploying a simple script&lt;/li&gt;
3048&lt;/ul&gt;
3049&lt;blockquote&gt;
3050&lt;p&gt;Make sure that you are using &lt;strong&gt;a good USB cable&lt;/strong&gt;. I had some problems with
3051mine and once I replaced it everything started to work.&lt;/p&gt;
3052&lt;/blockquote&gt;
3053&lt;h2 id=&#34;flashing-the-soc&#34;&gt;Flashing the SOC&lt;/h2&gt;
3054&lt;p&gt;Plug your ESP8266 to USB port and check if the device was recognized with
3055executing &lt;code&gt;dmesg | grep ch341-uart&lt;/code&gt;.&lt;/p&gt;
3056&lt;p&gt;Then check if the device is available under &lt;code&gt;/dev/&lt;/code&gt; by running &lt;code&gt;ls /dev/ttyUSB*&lt;/code&gt;.&lt;/p&gt;
3057&lt;blockquote&gt;
3058&lt;p&gt;&lt;strong&gt;Linux users&lt;/strong&gt;: if a device is not available be sure you are in &lt;code&gt;dialout&lt;/code&gt;
3059group. You can check this by executing &lt;code&gt;groups $USER&lt;/code&gt;. You can add a user to
3060&lt;code&gt;dialout&lt;/code&gt; group with &lt;code&gt;sudo adduser $USER dialout&lt;/code&gt;.&lt;/p&gt;
3061&lt;/blockquote&gt;
3062&lt;p&gt;After these conditions are meet go to the navigate to
3063&lt;a href=&#34;https://micropython.org/download/esp8266/&#34;&gt;https://micropython.org/download/esp8266/&lt;/a&gt;
3064and download &lt;code&gt;esp8266-20200902-v1.13.bin&lt;/code&gt;.&lt;/p&gt;
3065&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;mkdir esp8266-test
3066&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;cd esp8266-test
3067&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3068&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;wget https://micropython.org/resources/firmware/esp8266-20200902-v1.13.bin
3069&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;After obtaining firmware we will need some tooling to flash the firmware to the
3070board.&lt;/p&gt;
3071&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo pip3 install esptool
3072&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;You can read more about &lt;code&gt;esptool&lt;/code&gt; at
3073&lt;a href=&#34;https://github.com/espressif/esptool/&#34;&gt;https://github.com/espressif/esptool/&lt;/a&gt;.&lt;/p&gt;
3074&lt;p&gt;Before flashing the firmware we need to erase the flash on device. Substitute
3075&lt;code&gt;USB0&lt;/code&gt; with the device listed in output of &lt;code&gt;ls /dev/ttyUSB*&lt;/code&gt;.&lt;/p&gt;
3076&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;esptool.py --port /dev/ttyUSB0 erase_flash
3077&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;If flash was successfully erased it is now time to flash the new firmware to it.&lt;/p&gt;
3078&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;esptool.py --port /dev/ttyUSB0 --baud 460800 write_flash --flash_size=detect 0 esp8266-20200902-v1.13.bin
3079&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;If everything went ok you can try accessing MicroPython REPL with &lt;code&gt; screen /dev/ttyUSB0 115200&lt;/code&gt; or &lt;code&gt;picocom /dev/ttyUSB0 -b115200&lt;/code&gt;.&lt;/p&gt;
3080&lt;blockquote&gt;
3081&lt;p&gt;Sometimes you will need to press &lt;code&gt;ENTER&lt;/code&gt; in &lt;code&gt;screen&lt;/code&gt; or &lt;code&gt;picocom&lt;/code&gt; to access
3082REPL.&lt;/p&gt;
3083&lt;/blockquote&gt;
3084&lt;p&gt;When you are in REPL you can test if all is working properly following steps.&lt;/p&gt;
3085&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;gt; &lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; machine
3086&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;gt; machine.freq()
3087&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;This should output a number representing a frequency of the CPU (mine was
3088&lt;code&gt;80000000&lt;/code&gt;).&lt;/p&gt;
3089&lt;p&gt;When you are in &lt;code&gt;screen&lt;/code&gt; or &lt;code&gt;picocom&lt;/code&gt; these can help you a bit.&lt;/p&gt;
3090&lt;table&gt;
3091&lt;thead&gt;
3092&lt;tr&gt;
3093&lt;th&gt;Key&lt;/th&gt;
3094&lt;th&gt;Command&lt;/th&gt;
3095&lt;/tr&gt;
3096&lt;/thead&gt;
3097&lt;tbody&gt;
3098&lt;tr&gt;
3099&lt;td&gt;CTRL&#43;d&lt;/td&gt;
3100&lt;td&gt;preforms soft reboot&lt;/td&gt;
3101&lt;/tr&gt;
3102&lt;tr&gt;
3103&lt;td&gt;CTRL&#43;a x&lt;/td&gt;
3104&lt;td&gt;exits picocom&lt;/td&gt;
3105&lt;/tr&gt;
3106&lt;tr&gt;
3107&lt;td&gt;CTRL&#43;a \&lt;/td&gt;
3108&lt;td&gt;exits screen&lt;/td&gt;
3109&lt;/tr&gt;
3110&lt;/tbody&gt;
3111&lt;/table&gt;
3112&lt;h2 id=&#34;install-better-tooling&#34;&gt;Install better tooling&lt;/h2&gt;
3113&lt;p&gt;Now, to make our lives a little bit easier there are couple of additional tools
3114that will make this whole experience a little more bearable.&lt;/p&gt;
3115&lt;p&gt;There are twq cool ways of uploading local files to SOC flash.&lt;/p&gt;
3116&lt;ul&gt;
3117&lt;li&gt;ampy → &lt;a href=&#34;https://github.com/scientifichackers/ampy&#34;&gt;https://github.com/scientifichackers/ampy&lt;/a&gt;&lt;/li&gt;
3118&lt;li&gt;rshell → &lt;a href=&#34;https://github.com/dhylands/rshell&#34;&gt;https://github.com/dhylands/rshell&lt;/a&gt;&lt;/li&gt;
3119&lt;/ul&gt;
3120&lt;h3 id=&#34;ampy&#34;&gt;ampy&lt;/h3&gt;
3121&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# installing ampy&lt;/span&gt;
3122&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo pip3 install adafruit-ampy
3123&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Listed below are some common commands I used.&lt;/p&gt;
3124&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# uploads file to flash&lt;/span&gt;
3125&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ampy --delay 2 --port /dev/ttyUSB0 put boot.py
3126&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3127&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# lists file on flash&lt;/span&gt;
3128&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ampy --delay 2 --port /dev/ttyUSB0 ls
3129&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3130&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# outputs contents of file on flash&lt;/span&gt;
3131&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ampy --delay 2 --port /dev/ttyUSB0 cat boot.py
3132&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;blockquote&gt;
3133&lt;p&gt;I added &lt;code&gt;delay&lt;/code&gt; of 2 seconds because I had problems with executing commands.&lt;/p&gt;
3134&lt;/blockquote&gt;
3135&lt;h3 id=&#34;rshell&#34;&gt;rshell&lt;/h3&gt;
3136&lt;p&gt;Even though &lt;code&gt;ampy&lt;/code&gt; is a cool tool I opted with &lt;code&gt;rshell&lt;/code&gt; in the end since it&#39;s
3137much more polished and feature rich.&lt;/p&gt;
3138&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# installing ampy&lt;/span&gt;
3139&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo pip3 install rshell
3140&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Now that &lt;code&gt;rshell&lt;/code&gt; is installed we can connect to the board.&lt;/p&gt;
3141&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;rshell --buffer-size=30 -p /dev/ttyUSB0 -a
3142&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;This will open a shell inside bash and from here you can execute multiple
3143commands. You can check what is supported with &lt;code&gt;help&lt;/code&gt; once you are inside of a
3144shell.&lt;/p&gt;
3145&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;m@turing ~/Junk/esp8266-test
3146&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ rshell --buffer-size=30 -p /dev/ttyUSB0 -a
3147&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3148&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Using buffer-size of 30
3149&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Connecting to /dev/ttyUSB0 (buffer-size 30)...
3150&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Trying to connect to REPL connected
3151&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Testing &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; ubinascii.unhexlify exists ... Y
3152&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Retrieving root directories ... /boot.py/
3153&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Setting time ... Sep 06, 2020 23:54:28
3154&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Evaluating board_name ... pyboard
3155&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Retrieving time epoch ... Jan 01, 2000
3156&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Welcome to rshell. Use Control-D (or the exit command) to exit rshell.
3157&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;/home/m/Junk/esp8266-test&amp;gt; help
3158&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3159&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Documented commands (type help &amp;lt;topic&amp;gt;):
3160&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;========================================
3161&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;args cat connect date edit filesize help mkdir rm shell
3162&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;boards cd cp echo exit filetype ls repl rsync
3163&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3164&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Use Control-D (or the exit command) to exit rshell.
3165&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;blockquote&gt;
3166&lt;p&gt;Inside a shell &lt;code&gt;ls&lt;/code&gt; will display list of files on your machine. To get list
3167of files on flash folder &lt;code&gt;/pyboard&lt;/code&gt; is remapped inside the shell. To list files
3168on flash you must perform &lt;code&gt;ls /pyboard&lt;/code&gt;.&lt;/p&gt;
3169&lt;/blockquote&gt;
3170&lt;h4 id=&#34;moving-files-to-flash&#34;&gt;Moving files to flash&lt;/h4&gt;
3171&lt;p&gt;To avoid copying files all the time I used &lt;code&gt;rsync&lt;/code&gt; function from the inside of
3172&lt;code&gt;rshell&lt;/code&gt;.&lt;/p&gt;
3173&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;rsync . /pyboard
3174&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h4 id=&#34;executing-scripts&#34;&gt;Executing scripts&lt;/h4&gt;
3175&lt;p&gt;It is a pain to continuously reboot the device to trigger &lt;code&gt;/pyboard/boot.py&lt;/code&gt; and
3176there is a better way of testing local scripts on remote device.&lt;/p&gt;
3177&lt;p&gt;Lets assume we have &lt;code&gt;src/freq.py&lt;/code&gt; file that displays CPU frequency of a remote
3178device.&lt;/p&gt;
3179&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# src/freq.py&lt;/span&gt;
3180&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3181&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; machine
3182&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print(machine.freq())
3183&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Now lets upload this and execute it.&lt;/p&gt;
3184&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# syncs files to remove device&lt;/span&gt;
3185&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;rsync ./src /pyboard
3186&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3187&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# goes into REPL&lt;/span&gt;
3188&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;repl
3189&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3190&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# we import file by importing it without .py extension and this will run the script&lt;/span&gt;
3191&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;gt; import freq
3192&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3193&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# CTRL&#43;x will exit REPL&lt;/span&gt;
3194&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;additional-resources&#34;&gt;Additional resources&lt;/h2&gt;
3195&lt;ul&gt;
3196&lt;li&gt;&lt;a href=&#34;https://randomnerdtutorials.com/getting-started-micropython-esp32-esp8266/&#34;&gt;https://randomnerdtutorials.com/getting-started-micropython-esp32-esp8266/&lt;/a&gt;&lt;/li&gt;
3197&lt;li&gt;&lt;a href=&#34;http://docs.micropython.org/en/latest/esp8266/quickref.html&#34;&gt;http://docs.micropython.org/en/latest/esp8266/quickref.html&lt;/a&gt;&lt;/li&gt;
3198&lt;/ul&gt;
3199</content:encoded>
3200 </item>
3201
3202
3203
3204 <item>
3205 <title>Disable mouse wake from suspend with systemd service</title>
3206 <link>https://mitjafelicijan.com/disable-mouse-wake-from-suspend-with-systemd-service.html</link>
3207 <pubDate>Sat, 15 Aug 2020 12:00:00 &#43;0200</pubDate>
3208 <guid>https://mitjafelicijan.com/disable-mouse-wake-from-suspend-with-systemd-service.html</guid>
3209 <description>I recently bought ThinkPadX220 just as ajoke on eBay to test Linux distributions and play around with things and notdestroy my main machine.</description>
3210 <content:encoded>&lt;p&gt;I recently bought &lt;a href=&#34;https://www.laptopmag.com/reviews/laptops/lenovo-thinkpad-x220&#34;&gt;ThinkPad
3211X220&lt;/a&gt; just as a
3212joke on eBay to test Linux distributions and play around with things and not
3213destroy my main machine. Little to my knowledge I felt in love with it. Man,
3214they really made awesome machines back then.&lt;/p&gt;
3215&lt;p&gt;After changing disk that came with it to SSD and installing Ubuntu to test if 
3216everything works I noticed that even after a single touch of my external mouse
3217the system would wake up from sleep even though the lid was shut down.&lt;/p&gt;
3218&lt;p&gt;I wouldn&#39;t even noticed it if laptop didn&#39;t have &lt;a href=&#34;https://support.lenovo.com/lk/en/solutions/~/media/Images/ContentImages/p/pd025386_x1_status_03.ashx?w=426&amp;amp;h=262&#34;&gt;LED
3219sleep indicator&lt;/a&gt;.
3220I already had a bad experience with Linux and it&#39;s power management. I had a
3221&lt;a href=&#34;https://www.pcmag.com/reviews/dell-inspiron-15-7537&#34;&gt;Dell Inspiron 7537&lt;/a&gt; laptop
3222with a touchscreen and while traveling it decided to wake up and started cooking
3223in my backpack to the point that the digitizer responsible for touch actually
3224glue off and the whole screen got wrecked. So, I am a bit touchy about this.&lt;/p&gt;
3225&lt;p&gt;I went on solution hunting and to my surprise there is no easy way to disable
3226specific devices to perform wake up. Why is this not under the power management 
3227tab in setting is really strange.&lt;/p&gt;
3228&lt;p&gt;After googling for a solution I found &lt;a href=&#34;https://codetrips.com/2020/03/18/ubuntu-disable-mouse-wake-from-suspend/&#34;&gt;this nice article describing the
3229solution&lt;/a&gt;
3230that worked for me. The only problem with this solution was that he added his
3231solution to &lt;code&gt;.bashrc&lt;/code&gt; and this triggers &lt;code&gt;sudo&lt;/code&gt; that asks for a password each
3232time new terminal is opened, which get annoying quickly since I open a lot of
3233terminals all the time.&lt;/p&gt;
3234&lt;p&gt;I followed his instructions and got to solution &lt;code&gt;sudo sh -c &amp;quot;echo &#39;disabled&#39; &amp;gt; /sys/bus/usb/devices/2-1.1/power/wakeup&amp;quot;&lt;/code&gt;.&lt;/p&gt;
3235&lt;p&gt;I created a system service file &lt;code&gt;sudo nano /etc/systemd/system/disable-mouse-wakeup.service&lt;/code&gt; and removed &lt;code&gt;sudo&lt;/code&gt; and
3236replaced &lt;code&gt;sh&lt;/code&gt; with &lt;code&gt;/usr/bin/sh&lt;/code&gt; and pasted all that in &lt;code&gt;ExecStart&lt;/code&gt;.&lt;/p&gt;
3237&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;[Unit]&lt;/span&gt;
3238&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Description=&lt;span style=&#34;color:#a31515&#34;&gt;Disables wakeup on mouse event&lt;/span&gt;
3239&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;After=&lt;span style=&#34;color:#a31515&#34;&gt;network.target&lt;/span&gt;
3240&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;StartLimitIntervalSec=&lt;span style=&#34;color:#a31515&#34;&gt;0&lt;/span&gt;
3241&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3242&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;[Service]&lt;/span&gt;
3243&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Type=&lt;span style=&#34;color:#a31515&#34;&gt;simple&lt;/span&gt;
3244&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Restart=&lt;span style=&#34;color:#a31515&#34;&gt;always&lt;/span&gt;
3245&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;RestartSec=&lt;span style=&#34;color:#a31515&#34;&gt;1&lt;/span&gt;
3246&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;User=&lt;span style=&#34;color:#a31515&#34;&gt;root&lt;/span&gt;
3247&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ExecStart=&lt;span style=&#34;color:#a31515&#34;&gt;/usr/bin/sh -c &amp;#34;echo &amp;#39;disabled&amp;#39; &amp;gt; /sys/bus/usb/devices/2-1.1/power/wakeup&amp;#34;&lt;/span&gt;
3248&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3249&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;[Install]&lt;/span&gt;
3250&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;WantedBy=&lt;span style=&#34;color:#a31515&#34;&gt;multi-user.target&lt;/span&gt;
3251&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;After that I enabled, started and checked status of service.&lt;/p&gt;
3252&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo systemctl enable disable-mouse-wakeup.service
3253&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo systemctl start disable-mouse-wakeup.service
3254&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sudo systemctl status disable-mouse-wakeup.service
3255&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;This will permanently disable that device from wakeing up you computer on boot.
3256If you have many devices you would like to surpress from waking up your machine
3257I would create a shell script and call that instead of direclty doing it in
3258service file.&lt;/p&gt;
3259</content:encoded>
3260 </item>
3261
3262
3263
3264 <item>
3265 <title>Remote work and how it affects the daily lives of people</title>
3266 <link>https://mitjafelicijan.com/remote-work.html</link>
3267 <pubDate>Tue, 05 May 2020 12:00:00 &#43;0200</pubDate>
3268 <guid>https://mitjafelicijan.com/remote-work.html</guid>
3269 <description>I have been working remotely for the past 5 years.</description>
3270 <content:encoded>&lt;p&gt;I have been working remotely for the past 5 years. I love it. Love the freedom
3271and make your schedule thingy.&lt;/p&gt;
3272&lt;h2 id=&#34;you-work-more-not-less&#34;&gt;You work more not less&lt;/h2&gt;
3273&lt;p&gt;I&#39;ve heard from people things like: &amp;quot;Oh, you are so lucky, working from home,
3274having all the free time you want&amp;quot;. It was obvious they had no clue what means
3275working remotely. They had this romantic idea of remote work. You can watch TV
3276whenever you like, you can go outside for a picnic if you want and stuff like
3277that.&lt;/p&gt;
3278&lt;p&gt;This may be true if you work a day or two in a week from home. But if you go
3279completely remote all these changes completely. I take some time to acclimate
3280but then you start feeling the consequences of going fully remote. And it&#39;s not
3281all rainbows and unicorns. Rather the opposite.&lt;/p&gt;
3282&lt;h2 id=&#34;feeling-lost&#34;&gt;Feeling lost&lt;/h2&gt;
3283&lt;p&gt;At first, I remembered I felt lost. I was not used to this kind of environment.
3284It felt disoriented and a part of you that is used to procrastinate turns on.
3285You start thinking of a workday as a whole day. And soon this idea of &amp;quot;I can do
3286this later&amp;quot; starts creeping in. Well, I have the whole day ahead of me. I can do
3287this a bit later.&lt;/p&gt;
3288&lt;h2 id=&#34;hyper-performance&#34;&gt;Hyper-performance&lt;/h2&gt;
3289&lt;p&gt;As a direct result, you become more focused on your work since you don&#39;t have
3290all the interruptions common in the workplace. And you can quickly get used to
3291this hyper-performance. But this mode requires also a lot of peace and quiet.&lt;/p&gt;
3292&lt;p&gt;And here we come to the ugly parts of all this. &lt;strong&gt;People rarely have the
3293self-control&lt;/strong&gt; to not waste other people&#39;s time. It is paralyzing when people
3294start calling you, sending you chat messages, etc. The thing is, that when I
3295achieve this hyper-performance mode I am completely embroiled in the problem I
3296am solving and this kind of interruptions mess with your head. I need an hour at
3297least to get back in the zone. Sometimes not achieving the same focus the whole
3298day.&lt;/p&gt;
3299&lt;p&gt;I know that life is not how you want it to be and takes its route but from what
3300I&#39;ve learned this kind of interruptions can be avoided in 90% of the case easily
3301just by closing any chat programs and putting your phone in a drawer.&lt;/p&gt;
3302&lt;h2 id=&#34;suggestion-to-all-the-new-remote-workers&#34;&gt;Suggestion to all the new remote workers&lt;/h2&gt;
3303&lt;ul&gt;
3304&lt;li&gt;Stop wasting other people&#39;s time. You don&#39;t bother people at their desks in
3305the office either.&lt;/li&gt;
3306&lt;li&gt;Do not replace daily chats in the hallways with instant messaging software.
3307It will only interrupt people. Nothing good will come of it.&lt;/li&gt;
3308&lt;li&gt;Set your working hours and try to not allow it to bleed outside these
3309boundaries and maintain your routine.&lt;/li&gt;
3310&lt;li&gt;Be prepared that hours will be longer regardless of your good intentions and
3311your well thought of routine.&lt;/li&gt;
3312&lt;li&gt;Try to be hyper-focused and do only one thing at the time. Multitasking is the
3313enemy of progress.&lt;/li&gt;
3314&lt;li&gt;Avoid long meetings and if possible eliminate them. Rather take time to write
3315them out and allow others to respond in their own time. Meetings are usually a
3316large waste of time and most of the people attending them are there just
3317because the manager said so.&lt;/li&gt;
3318&lt;li&gt;The software will not solve your problems. And throwing money at problems
3319neither.&lt;/li&gt;
3320&lt;li&gt;If you are in a managerial position don&#39;t supervise any single minute of
3321workers. They are probably giving you more hours anyways. Track progress
3322weekly not daily. You hired them and give them the benefit of the doubt that
3323they will deliver what you agreed upon.&lt;/li&gt;
3324&lt;/ul&gt;
3325</content:encoded>
3326 </item>
3327
3328
3329
3330 <item>
3331 <title>My love and hate relationship with Node.js</title>
3332 <link>https://mitjafelicijan.com/my-love-and-hate-relationship-with-nodejs.html</link>
3333 <pubDate>Mon, 30 Mar 2020 12:00:00 &#43;0200</pubDate>
3334 <guid>https://mitjafelicijan.com/my-love-and-hate-relationship-with-nodejs.html</guid>
3335 <description>Previous project I was working on was being coded inGolang.</description>
3336 <content:encoded>&lt;p&gt;Previous project I was working on was being coded in
3337&lt;a href=&#34;https://golang.org/&#34;&gt;Golang&lt;/a&gt;. Also was my first project using it. And damn,
3338that was an awesome experience. The whole thing is just superb. From how errors
3339are handled. The C-like way you handle compiling. The way the language is
3340structured making it incredibly versatile and easy to learn.&lt;/p&gt;
3341&lt;p&gt;It may cause some pain for somebody that is not used of using interfaces to map
3342JSON and doing the recompilation all the time. But we have tools like
3343&lt;a href=&#34;http://eradman.com/entrproject/&#34;&gt;entr&lt;/a&gt; and
3344&lt;a href=&#34;https://www.gnu.org/software/make/&#34;&gt;make&lt;/a&gt; to fix that.&lt;/p&gt;
3345&lt;p&gt;But we are not here to talk about my undying love for &lt;strong&gt;Golang&lt;/strong&gt;. Only in some
3346way we probably should. It is an excellent example of how modern language should
3347be designed. And because I have used it extensively in the last couple of years
3348this probably taints my views of other languages. And is doing me a great
3349disservice. Nevertheless, here we are.&lt;/p&gt;
3350&lt;p&gt;About two years ago I started flirting with &lt;a href=&#34;https://nodejs.org/en/&#34;&gt;Node.js&lt;/a&gt;
3351for a project I started working on. What I wanted was to have things written in
3352a language that is widely used, and we could get additional developers for. As
3353much as &lt;strong&gt;Golang&lt;/strong&gt; is amazing it&#39;s really hard to get developers for it. Even
3354now. And after playing around with it for a week I felt in love with the speed
3355of iteration and massive package ecosystem. Do you want SSO? You got it! Do you
3356want some esoteric library for something? There is a strong chance somebody
3357wrote it. It is so extensive that you find yourself evaluating packages based on
3358&lt;strong&gt;GitHub stars&lt;/strong&gt; and number of contributors. You get swallowed by the vanity
3359metrics and that potentially will become the downfall of Node.js.&lt;/p&gt;
3360&lt;p&gt;Because of the sheer amount of choice I often got anxiety when choosing
3361libraries. Will I choose the correct one? Is this library something that will be
3362supported for a foreseeable future or not? I am used of using libraries that are
3363being in development for 10 years plus (Python, C) and that gave me some sort of
3364comfort. And it is probably unfair to Node.js and community to expect same
3365dedication.&lt;/p&gt;
3366&lt;p&gt;Moving forward ... Work started and things were great. &lt;strong&gt;Speed of iteration was
3367insane&lt;/strong&gt;. For some feature that I would need a day in Golang only took me hour
3368or two. I became lazy! Using packages all over the place. Falling into the same
3369trap as others. Packages on top of packages. And &lt;a href=&#34;https://www.npmjs.com/&#34;&gt;npm&lt;/a&gt;
3370didn&#39;t help at all. The way that the package manager works is just
3371horrendous. And not allowing to have node_modules outside the project is also
3372the stupidest idea ever.&lt;/p&gt;
3373&lt;p&gt;So at that point I started feeling the technical debt that comes with Node.js
3374and the whole ecosystem. What nobody tells you is that &lt;strong&gt;structuring large
3375Node.js apps&lt;/strong&gt; is more problematic than one would think. And going microservice
3376for every single thing is also a bad idea. The amount of networking you
3377introduce with that approach always ends up being a pain in the ass. And I don&#39;t
3378even want to go into system administration here. The overhead is
3379insane. Package-lock.json made many days feel like living hell for me. And I
3380would eat the cost of all this if it meant for better development
3381experience. Well, it didn&#39;t.&lt;/p&gt;
3382&lt;p&gt;The &lt;strong&gt;lack of Typescript&lt;/strong&gt; support in the interpreter is still mind boggling to
3383me. Why haven&#39;t they added native support yet for this is beyond me?! That would
3384have solved so many problems. Lack of type safety became a problem somewhere in
3385the middle of the project where the codebase was sufficiently large enough to
3386present problems. We started adding arguments to functions and there was &lt;strong&gt;no
3387way to implicitly define argument types&lt;/strong&gt;. And because at that point there were
3388a lot of functions, it became impossible to know what each one accepts,
3389development became more and more trial and error based.&lt;/p&gt;
3390&lt;p&gt;I tried &lt;strong&gt;implementing Typescript&lt;/strong&gt;, but that would present a large refactor
3391that we were not willing to do at that point. The benefits were not enough. I
3392also tried &lt;a href=&#34;https://flow.org/&#34;&gt;Flow - static type checker&lt;/a&gt; but implementation
3393was also horrible. What Typescript and Flow forces you is to have src folder and
3394then &lt;strong&gt;transpile&lt;/strong&gt; your code into dist folder and run it with node. WTH is that
3395all about. Why can&#39;t this be done in memory or some virtual file system? Why? I
3396see no reason why this couldn&#39;t be done like this. But it is what it is. I
3397abandoned all hope for static type checking.&lt;/p&gt;
3398&lt;p&gt;One of the problems that resulted from not having interfaces or types was
3399inability to model out our data from &lt;strong&gt;Elasticsearch&lt;/strong&gt;. I could have done a
3400&lt;strong&gt;pedestrian implementation&lt;/strong&gt; of it, but there must be a better way of doing
3401this without resorting to some hack basically. Or maybe I haven&#39;t found a
3402solution, which is also a possibility. I have looked, though. No juice!&lt;/p&gt;
3403&lt;p&gt;&lt;strong&gt;Error handling?&lt;/strong&gt; Is that a joke?&lt;/p&gt;
3404&lt;p&gt;Thank god for &lt;strong&gt;await/async&lt;/strong&gt;. Without it, I would have probably just abandoned
3405the whole thing and went with something else like Python. That&#39;s all I am going
3406to say about this :)&lt;/p&gt;
3407&lt;p&gt;I started asking myself a question if Node.js is actually ready to be used in a
3408&lt;strong&gt;large scale applications&lt;/strong&gt;? And this was a totally wrong question. What I
3409should have been asking myself was, how to use Node.js in large scale
3410application. And you don&#39;t get this in &lt;strong&gt;marketing material&lt;/strong&gt; for Express or Koa
3411etc. They never tell you this. Making Node.js scale on infrastructure or in
3412codebase is really &lt;strong&gt;more of an art than a science&lt;/strong&gt;. And just like with the
3413whole JavaScript ecosystem:&lt;/p&gt;
3414&lt;ul&gt;
3415&lt;li&gt;impossible to master,&lt;/li&gt;
3416&lt;li&gt;half of your time you work on your tooling,&lt;/li&gt;
3417&lt;li&gt;just accept transpilers that convert one code into another (holly smokes),&lt;/li&gt;
3418&lt;li&gt;error handling is a joke,&lt;/li&gt;
3419&lt;li&gt;standards? What standards?&lt;/li&gt;
3420&lt;/ul&gt;
3421&lt;p&gt;But on the other hand. As I did, you will also learn to love it. Learn to use it
3422quickly and do impossible things in crazy limited time.&lt;/p&gt;
3423&lt;p&gt;I hate to admit it. But I love Node.js. Dammit, I love it :)&lt;/p&gt;
3424&lt;p&gt;&lt;strong&gt;2023 Update&lt;/strong&gt;: I hate Node.js!&lt;/p&gt;
3425</content:encoded>
3426 </item>
3427
3428
3429
3430 <item>
3431 <title>The strange case of Elasticsearch allocation failure</title>
3432 <link>https://mitjafelicijan.com/the-strange-case-of-elasticsearch-allocation-failure.html</link>
3433 <pubDate>Sun, 29 Mar 2020 12:00:00 &#43;0200</pubDate>
3434 <guid>https://mitjafelicijan.com/the-strange-case-of-elasticsearch-allocation-failure.html</guid>
3435 <description>I&amp;#39;ve been using Elasticsearch in production for 5 years now and never had asingle problem with it.</description>
3436 <content:encoded>&lt;p&gt;I&#39;ve been using Elasticsearch in production for 5 years now and never had a
3437single problem with it. Hell, never even known there could be a problem. Just
3438worked. All this time. The first node that I deployed is still being used in
3439production, never updated, upgraded, touched in anyway.&lt;/p&gt;
3440&lt;p&gt;All this bliss came to an abrupt end this Friday when I got notification that
3441Elasticsearch cluster went warm. Well, warm is not that bad right? Wrong!
3442Quickly after that I got another email which sent chills down my spine. Cluster
3443is now red. RED! Now, shit really hit the fan!&lt;/p&gt;
3444&lt;p&gt;I tried googling what could be the problem and after executing allocation
3445function noticed that some shards were unassigned and 5 attempts were already
3446made (which is BTW to my luck the maximum) and that meant I am basically fucked.
3447They also applied that one should wait for cluster to re-balance itself. So, I
3448waited. One hour, two hours, several hours. Nothing, still RED.&lt;/p&gt;
3449&lt;p&gt;The strangest thing about it all was, that queries were still being fulfilled.
3450Data was coming out. On the outside it looked like nothing was wrong but
3451everybody that would look at the cluster would know immediately that something
3452was very very wrong and we were living on borrowed time here.&lt;/p&gt;
3453&lt;blockquote&gt;
3454&lt;p&gt;&lt;strong&gt;Please, DO NOT do what I did.&lt;/strong&gt; Seriously! Please ask someone on official
3455forums or if you know an expert please consult him. There could be million of
3456reasons and these solution fit my problem. Maybe in your case it would
3457disastrous. I had all the data backed up and even if I would fail spectacularly
3458I would be able to restore the data. It would be a huge pain and I would loose
3459couple of days but I had a plan B.&lt;/p&gt;
3460&lt;/blockquote&gt;
3461&lt;p&gt;Executing allocation and told me what the problem was but no clear solution yet.&lt;/p&gt;
3462&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;GET /_cat/allocation?format=json
3463&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;I got a message that &lt;code&gt;ALLOCATION_FAILED&lt;/code&gt; with additional info &lt;code&gt;failed to create shard, failure ioexception[failed to obtain in-memory shard lock]&lt;/code&gt;. Well
3464splendid! I must also say that our cluster is capable more than enough to handle
3465the traffic. Also JVM memory pressure never was an issue. So what happened
3466really then?&lt;/p&gt;
3467&lt;p&gt;I tried also re-routing failed ones with no success due to AWS restrictions on
3468having managed Elasticsearch cluster (they lock some of the functions).&lt;/p&gt;
3469&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;POST /_cluster/reroute?retry_failed=true
3470&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;I got a message that significantly reduced my options.&lt;/p&gt;
3471&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;{
3472&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;Message&amp;#34;: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Your request: &amp;#39;/_cluster/reroute&amp;#39; is not allowed.&amp;#34;&lt;/span&gt;
3473&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
3474&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;After that I went on a hunt again. I won&#39;t bother you with all the details
3475because hours/days went by until I was finally able to re-index the problematic
3476index and hoped for the best. Until that moment even re-indexing was giving me
3477errors.&lt;/p&gt;
3478&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;POST _reindex
3479&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;{
3480&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;source&amp;#34;: {
3481&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;index&amp;#34;: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;myindex&amp;#34;&lt;/span&gt;
3482&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; },
3483&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;dest&amp;#34;: {
3484&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;index&amp;#34;: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;myindex-new&amp;#34;&lt;/span&gt;
3485&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
3486&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
3487&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;I needed to do this multiple times to get all the documents re-indexed. Then I
3488dropped the original one with the following command.&lt;/p&gt;
3489&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;DELETE /myindex
3490&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;And re-indexed again new one in the original one (well by name only).&lt;/p&gt;
3491&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;POST _reindex
3492&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;{
3493&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;source&amp;#34;: {
3494&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;index&amp;#34;: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;myindex-new&amp;#34;&lt;/span&gt;
3495&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; },
3496&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;dest&amp;#34;: {
3497&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;index&amp;#34;: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;myindex&amp;#34;&lt;/span&gt;
3498&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
3499&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
3500&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;On the surface it looks like all is working but I have a long road in front of
3501me to get all the things working again. Cluster now shows that it is in Green
3502mode but I am also getting a notification that the cluster has processing status
3503which could mean million of things.&lt;/p&gt;
3504&lt;p&gt;Godspeed!&lt;/p&gt;
3505</content:encoded>
3506 </item>
3507
3508
3509
3510 <item>
3511 <title>Create placeholder images with sharp Node.js image processing library</title>
3512 <link>https://mitjafelicijan.com/create-placeholder-images-with-sharp.html</link>
3513 <pubDate>Fri, 27 Mar 2020 12:00:00 &#43;0200</pubDate>
3514 <guid>https://mitjafelicijan.com/create-placeholder-images-with-sharp.html</guid>
3515 <description>I have been searching for a solution to pre-generate some placeholder images forimage server I needed to develop that resizes images on S3.</description>
3516 <content:encoded>&lt;p&gt;I have been searching for a solution to pre-generate some placeholder images for
3517image server I needed to develop that resizes images on S3. I though this would
3518be a 15min job and quickly found out how very mistaken I was.&lt;/p&gt;
3519&lt;p&gt;Even though Node.js is not really the best way to do this kind of things (surely
3520something written in C or Rust or even Golang would be the correct way to do
3521this but we didn&#39;t need the speed in our case) I found an excellent library
3522&lt;a href=&#34;https://github.com/lovell/sharp&#34;&gt;sharp - High performance Node.js image
3523processing&lt;/a&gt;.&lt;/p&gt;
3524&lt;p&gt;Getting things running was a breeze.&lt;/p&gt;
3525&lt;h2 id=&#34;fetch-image-from-s3-and-save-resized&#34;&gt;Fetch image from S3 and save resized&lt;/h2&gt;
3526&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; sharp = require(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;sharp&amp;#39;&lt;/span&gt;);
3527&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; aws = require(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;aws-sdk&amp;#39;&lt;/span&gt;);
3528&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3529&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; x,y = 100;
3530&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; s3 = &lt;span style=&#34;color:#00f&#34;&gt;new&lt;/span&gt; aws.S3({});
3531&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3532&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;aws.config.update({
3533&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; secretAccessKey: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;secretAccessKey&amp;#39;&lt;/span&gt;,
3534&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; accessKeyId: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;accessKeyId&amp;#39;&lt;/span&gt;,
3535&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; region: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;region&amp;#39;&lt;/span&gt;
3536&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;});
3537&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3538&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; originalImage = &lt;span style=&#34;color:#00f&#34;&gt;await&lt;/span&gt; s3.getObject({
3539&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Bucket: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;some-bucket-name&amp;#39;&lt;/span&gt;,
3540&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Key: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;image.jpg&amp;#39;&lt;/span&gt;,
3541&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}).promise();
3542&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3543&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; resizedImage = &lt;span style=&#34;color:#00f&#34;&gt;await&lt;/span&gt; sharp(originalImage.Body)
3544&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; .resize(x, y)
3545&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; .jpeg({ progressive: &lt;span style=&#34;color:#00f&#34;&gt;true&lt;/span&gt; })
3546&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; .toBuffer();
3547&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3548&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;s3.putObject({
3549&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Bucket: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;some-bucket-name&amp;#39;&lt;/span&gt;,
3550&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Key: &lt;span style=&#34;color:#a31515&#34;&gt;`optimized/&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;${&lt;/span&gt;x&lt;span style=&#34;color:#a31515&#34;&gt;}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;x&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;${&lt;/span&gt;y&lt;span style=&#34;color:#a31515&#34;&gt;}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;/image.jpg`&lt;/span&gt;,
3551&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Body: resizedImage,
3552&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; ContentType: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;image/jpeg&amp;#39;&lt;/span&gt;,
3553&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; ACL: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;public-read&amp;#39;&lt;/span&gt;
3554&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}).promise();
3555&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;All this code was wrapped inside a web service with some additional security
3556checks and defensive coding to detect if key is missing on S3.&lt;/p&gt;
3557&lt;p&gt;And at that point I needed to return placeholder images as a response in case
3558key is missing or x,y are not allowed by the server etc. I could have created
3559PNG in Gimp and just serve them but I wanted to respect aspect ratio and I
3560didn&#39;t want to return some mangled images.&lt;/p&gt;
3561&lt;blockquote&gt;
3562&lt;p&gt;Main problem with finding a clean solution I could copy and paste and change a
3563bit was a task. API is changing constantly and there weren&#39;t clear examples or
3564I was unable to find them.&lt;/p&gt;
3565&lt;/blockquote&gt;
3566&lt;h2 id=&#34;generating-placeholder-images-using-svg&#34;&gt;Generating placeholder images using SVG&lt;/h2&gt;
3567&lt;p&gt;What I ended up was using SVG to generate text and created image with sharp and
3568used composition to combine both layers. Response returned by this function is a
3569buffer you can use to either upload to S3 or save to local file.&lt;/p&gt;
3570&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; generatePlaceholderImageWithText = &lt;span style=&#34;color:#00f&#34;&gt;async&lt;/span&gt; (width, height, message) =&amp;gt; {
3571&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; overlay = &lt;span style=&#34;color:#a31515&#34;&gt;`&amp;lt;svg width=&amp;#34;&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;${&lt;/span&gt;width - 20&lt;span style=&#34;color:#a31515&#34;&gt;}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34; height=&amp;#34;&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;${&lt;/span&gt;height - 20&lt;span style=&#34;color:#a31515&#34;&gt;}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&amp;gt;
3572&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; &amp;lt;text x=&amp;#34;50%&amp;#34; y=&amp;#34;50%&amp;#34; font-family=&amp;#34;sans-serif&amp;#34; font-size=&amp;#34;16&amp;#34; text-anchor=&amp;#34;middle&amp;#34;&amp;gt;&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;${&lt;/span&gt;message&lt;span style=&#34;color:#a31515&#34;&gt;}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;lt;/text&amp;gt;
3573&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; &amp;lt;/svg&amp;gt;`&lt;/span&gt;;
3574&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3575&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;await&lt;/span&gt; sharp({
3576&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; create: {
3577&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; width: width,
3578&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; height: height,
3579&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; channels: 4,
3580&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; background: { r: 230, g: 230, b: 230, alpha: 1 }
3581&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
3582&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; })
3583&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; .composite([{
3584&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; input: Buffer.from(overlay),
3585&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; gravity: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;center&amp;#39;&lt;/span&gt;,
3586&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }])
3587&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; .jpeg()
3588&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; .toBuffer();
3589&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
3590&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;That is about it. Nothing more to it. You can change the color of the image by
3591changing &lt;code&gt;background&lt;/code&gt; and if you want to change text styling you can adapt SVG
3592to your needs.&lt;/p&gt;
3593&lt;blockquote&gt;
3594&lt;p&gt;Also be careful about the length of the text. This function positions text at
3595the center and adds &lt;code&gt;20px&lt;/code&gt; padding on all sides. If text is longer than the
3596image it will get cut.&lt;/p&gt;
3597&lt;/blockquote&gt;
3598</content:encoded>
3599 </item>
3600
3601
3602
3603 <item>
3604 <title>Simple Server-Sent Events based PubSub Server</title>
3605 <link>https://mitjafelicijan.com/simple-server-sent-events-based-pubsub-server.html</link>
3606 <pubDate>Sun, 22 Mar 2020 12:00:00 &#43;0200</pubDate>
3607 <guid>https://mitjafelicijan.com/simple-server-sent-events-based-pubsub-server.html</guid>
3608 <description>Before we continue .</description>
3609 <content:encoded>&lt;h2 id=&#34;before-we-continue-&#34;&gt;Before we continue ...&lt;/h2&gt;
3610&lt;p&gt;Publisher Subscriber model is nothing new and there are many amazing solutions
3611out there, so writing a new one would be a waste of time if other solutions
3612wouldn&#39;t have quite complex install procedures and weren&#39;t so hard to maintain.
3613But to be fair, comparing this simple server with something like
3614&lt;a href=&#34;https://kafka.apache.org/&#34;&gt;Kafka&lt;/a&gt; or &lt;a href=&#34;https://www.rabbitmq.com/&#34;&gt;RabbitMQ&lt;/a&gt; is
3615laughable at the least. Those solutions are enterprise grade and have many
3616mechanisms there to ensure messages aren&#39;t lost and much more. Regardless of
3617these drawbacks, this method has been tested on a large website and worked until
3618now without any problems. So now, that we got that cleared up, let&#39;s continue.&lt;/p&gt;
3619&lt;p&gt;&lt;em&gt;&lt;strong&gt;Wiki definition:&lt;/strong&gt; Publish/subscribe messaging, or pub/sub messaging, is a
3620form of asynchronous service-to-service communication used in serverless and
3621microservices architectures. In a pub/sub model, any message published to a
3622topic is immediately received by all the subscribers to the topic.&lt;/em&gt;&lt;/p&gt;
3623&lt;h2 id=&#34;general-goals&#34;&gt;General goals&lt;/h2&gt;
3624&lt;ul&gt;
3625&lt;li&gt;provide a simple server that relays messages to all the connected clients,&lt;/li&gt;
3626&lt;li&gt;messages can be posted on specific topics,&lt;/li&gt;
3627&lt;li&gt;messages get sent via &lt;a href=&#34;https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events&#34;&gt;Server-Sent
3628Events&lt;/a&gt;
3629to all the subscribers.&lt;/li&gt;
3630&lt;/ul&gt;
3631&lt;h2 id=&#34;how-exactly-does-the-pubsub-model-work&#34;&gt;How exactly does the pub/sub model work?&lt;/h2&gt;
3632&lt;p&gt;The easiest way to explain this is with diagram bellow. Basic function is
3633simple. We have subscribers that receive messages, and we have publishers that
3634create and post messages. Similar model is also well know pattern that works on
3635a premise of consumers and producers, and they take similar roles.&lt;/p&gt;
3636&lt;figure&gt;
3637&lt;img src=&#34;/posts/simple-pubsub-server/pubsub-overview.png&#34; alt=&#34;How PubSub works&#34; /&gt;
3638&lt;/figure&gt;
3639&lt;p&gt;&lt;strong&gt;These are some naive characteristics we want to achieve:&lt;/strong&gt;&lt;/p&gt;
3640&lt;ul&gt;
3641&lt;li&gt;producer is publishing messages to subscribe topic,&lt;/li&gt;
3642&lt;li&gt;consumer is receiving messages from subscribed topic,&lt;/li&gt;
3643&lt;li&gt;servers is also known as Broker,&lt;/li&gt;
3644&lt;li&gt;broker does not store messages or tracks success,&lt;/li&gt;
3645&lt;li&gt;broker uses
3646&lt;a href=&#34;https://en.wikipedia.org/wiki/FIFO_(computing_and_electronics)&#34;&gt;FIFO&lt;/a&gt; method
3647for delivering messages,&lt;/li&gt;
3648&lt;li&gt;if consumer wants to receive messages from a topic, producer and consumer
3649topics must match,&lt;/li&gt;
3650&lt;li&gt;consumer can subscribe to multiple topics,&lt;/li&gt;
3651&lt;li&gt;producer can publish to multiple topics,&lt;/li&gt;
3652&lt;li&gt;each message has a messageId.&lt;/li&gt;
3653&lt;/ul&gt;
3654&lt;p&gt;&lt;strong&gt;Known drawbacks:&lt;/strong&gt;&lt;/p&gt;
3655&lt;ul&gt;
3656&lt;li&gt;messages will not be stored in a persistent queue or unreceived messages like
3657&lt;a href=&#34;https://en.wikipedia.org/wiki/Dead_letter_queue&#34;&gt;DeadLetterQueue&lt;/a&gt; so old
3658messages could be lost on server restart,&lt;/li&gt;
3659&lt;li&gt;&lt;a href=&#34;https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events&#34;&gt;Server-Sent
3660Events&lt;/a&gt;
3661opens a long-running connection between the client and the server so make sure
3662if your setup is load balanced that the load balancer in this case can have
3663long opened connection,&lt;/li&gt;
3664&lt;li&gt;no system moderation due to the dynamic nature of creating queues.&lt;/li&gt;
3665&lt;/ul&gt;
3666&lt;h2 id=&#34;server-sent-events&#34;&gt;Server-Sent Events&lt;/h2&gt;
3667&lt;p&gt;Read more about it on &lt;a href=&#34;https://html.spec.whatwg.org/multipage/server-sent-events.html&#34;&gt;official specification
3668page&lt;/a&gt;.&lt;/p&gt;
3669&lt;h3 id=&#34;current-browser-support&#34;&gt;Current browser support&lt;/h3&gt;
3670&lt;figure&gt;
3671&lt;img src=&#34;/posts/simple-pubsub-server/caniuse.png&#34; alt=&#34;Browser support&#34; /&gt;
3672&lt;/figure&gt;
3673&lt;p&gt;Check
3674&lt;a href=&#34;https://caniuse.com/#feat=eventsource&#34;&gt;https://caniuse.com/#feat=eventsource&lt;/a&gt;
3675for latest information about browser support.&lt;/p&gt;
3676&lt;h3 id=&#34;known-issues&#34;&gt;Known issues&lt;/h3&gt;
3677&lt;ul&gt;
3678&lt;li&gt;Firefox 52 and below do not support EventSource in web/shared workers&lt;/li&gt;
3679&lt;li&gt;In Firefox prior to version 36 server-sent events do not reconnect
3680automatically in case of a connection interrupt (bug)&lt;/li&gt;
3681&lt;li&gt;Reportedly, CORS in EventSource is currently supported in Firefox 10&#43;, Opera
368212&#43;, Chrome 26&#43;, Safari 7.0&#43;.&lt;/li&gt;
3683&lt;li&gt;Antivirus software may block the event streaming data chunks.&lt;/li&gt;
3684&lt;/ul&gt;
3685&lt;p&gt;Source: &lt;a href=&#34;https://caniuse.com/#feat=eventsource&#34;&gt;https://caniuse.com/#feat=eventsource&lt;/a&gt;&lt;/p&gt;
3686&lt;h3 id=&#34;message-format&#34;&gt;Message format&lt;/h3&gt;
3687&lt;p&gt;The simplest message that can be sent is only with data attribute:&lt;/p&gt;
3688&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;data: this is a simple message
3689&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;lt;blank line&amp;gt;
3690&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;You can send message IDs to be used if the connection is dropped:&lt;/p&gt;
3691&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;id: 33
3692&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;data: this is line one
3693&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;data: this is line two
3694&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;lt;blank line&amp;gt;
3695&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;And you can specify your own event types (the above messages will all trigger
3696the message event):&lt;/p&gt;
3697&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;id: 36
3698&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;event: price
3699&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;data: 103.34
3700&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;lt;blank line&amp;gt;
3701&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h3 id=&#34;server-requirements&#34;&gt;Server requirements&lt;/h3&gt;
3702&lt;p&gt;The important thing is how you send headers and which headers are sent by the
3703server that triggers browser to threat response as a EventStream.&lt;/p&gt;
3704&lt;p&gt;Headers responsible for this are:&lt;/p&gt;
3705&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Content-Type: text/event-stream
3706&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Cache-Control: no-cache
3707&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Connection: keep-alive
3708&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h3 id=&#34;debugging-with-google-chrome&#34;&gt;Debugging with Google Chrome&lt;/h3&gt;
3709&lt;p&gt;Google Chrome provides build-in debugging and exploration tool for &lt;a href=&#34;https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events&#34;&gt;Server-Sent
3710Events&lt;/a&gt;
3711which is quite nice and available from Developer Tools under Network tab.&lt;/p&gt;
3712&lt;blockquote&gt;
3713&lt;p&gt;You can debug only client side events that get received and not the server
3714ones. For debugging server events add &lt;code&gt;console.log&lt;/code&gt; to &lt;code&gt;server.js&lt;/code&gt; code and
3715print out events.&lt;/p&gt;
3716&lt;/blockquote&gt;
3717&lt;figure&gt;
3718&lt;img src=&#34;/posts/simple-pubsub-server/chrome-debugging.png&#34; alt=&#34;Google Chrome Developer Tools EventStream&#34; /&gt;
3719&lt;/figure&gt;
3720&lt;h2 id=&#34;server-implementation&#34;&gt;Server implementation&lt;/h2&gt;
3721&lt;p&gt;For the sake of this example we will use &lt;a href=&#34;https://nodejs.org/en/&#34;&gt;Node.js&lt;/a&gt; with
3722&lt;a href=&#34;https://expressjs.com&#34;&gt;Express&lt;/a&gt; as our router since this is the easiest way to
3723get started and we will use already written SSE library for node
3724&lt;a href=&#34;https://www.npmjs.com/package/sse-pubsub&#34;&gt;sse-pubsub&lt;/a&gt; so we don&#39;t reinvent the
3725wheel.&lt;/p&gt;
3726&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;npm init --yes
3727&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3728&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;npm install express
3729&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;npm install body-parser
3730&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;npm install sse-pubsub
3731&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Basic implementation of a server (&lt;code&gt;server.js&lt;/code&gt;):&lt;/p&gt;
3732&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; express = require(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;express&amp;#39;&lt;/span&gt;);
3733&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; bodyParser = require(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;body-parser&amp;#39;&lt;/span&gt;);
3734&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; SSETopic = require(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;sse-pubsub&amp;#39;&lt;/span&gt;);
3735&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3736&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; app = express();
3737&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; port = process.env.PORT || 4000;
3738&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3739&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// topics container
3740&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; sseTopics = {};
3741&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3742&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;app.use(bodyParser.json());
3743&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3744&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// open for all cors
3745&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;app.all(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;*&amp;#39;&lt;/span&gt;, (req, res, next) =&amp;gt; {
3746&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; res.header(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;Access-Control-Allow-Origin&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;*&amp;#39;&lt;/span&gt;);
3747&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; res.header(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;Access-Control-Allow-Headers&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;X-Requested-With, Content-Type&amp;#39;&lt;/span&gt;);
3748&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; next();
3749&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;});
3750&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3751&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// preflight request error fix
3752&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;app.options(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;*&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#00f&#34;&gt;async&lt;/span&gt; (req, res) =&amp;gt; {
3753&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; res.header(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;Access-Control-Allow-Origin&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;*&amp;#39;&lt;/span&gt;);
3754&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; res.header(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;Access-Control-Allow-Headers&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;X-Requested-With, Content-Type&amp;#39;&lt;/span&gt;);
3755&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; res.send(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;OK&amp;#39;&lt;/span&gt;);
3756&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;});
3757&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3758&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// serve the event streams
3759&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;app.get(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;/stream/:topic&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#00f&#34;&gt;async&lt;/span&gt; (req, res, next) =&amp;gt; {
3760&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; topic = req.params.topic;
3761&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3762&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; (!(topic &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; sseTopics)) {
3763&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; sseTopics[topic] = &lt;span style=&#34;color:#00f&#34;&gt;new&lt;/span&gt; SSETopic({
3764&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; pingInterval: 0,
3765&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; maxStreamDuration: 15000,
3766&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; });
3767&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
3768&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3769&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// subscribing client to topic
3770&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; sseTopics[topic].subscribe(req, res);
3771&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;});
3772&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3773&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// accepts new messages into topic
3774&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;app.post(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;/publish&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#00f&#34;&gt;async&lt;/span&gt; (req, res) =&amp;gt; {
3775&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;let&lt;/span&gt; body = req.body;
3776&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;let&lt;/span&gt; status = 200;
3777&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3778&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; console.log(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;Incoming message:&amp;#39;&lt;/span&gt;, req.body);
3779&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3780&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; (
3781&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; body.hasOwnProperty(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;topic&amp;#39;&lt;/span&gt;) &amp;amp;&amp;amp;
3782&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; body.hasOwnProperty(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;event&amp;#39;&lt;/span&gt;) &amp;amp;&amp;amp;
3783&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; body.hasOwnProperty(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;message&amp;#39;&lt;/span&gt;)
3784&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; ) {
3785&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; topic = req.body.topic;
3786&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; event = req.body.event;
3787&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; message = req.body.message;
3788&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3789&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; (topic &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; sseTopics) {
3790&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// sends message to all the subscribers
3791&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; sseTopics[topic].publish(message, event);
3792&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
3793&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; } &lt;span style=&#34;color:#00f&#34;&gt;else&lt;/span&gt; {
3794&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; status = 400;
3795&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
3796&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3797&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; res.status(status).send({
3798&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; status,
3799&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; });
3800&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;});
3801&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3802&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// returns JSON object of all opened topics
3803&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;app.get(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;/status&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#00f&#34;&gt;async&lt;/span&gt; (req, res) =&amp;gt; {
3804&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; res.send(sseTopics);
3805&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;});
3806&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3807&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// health-check endpoint
3808&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;app.get(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;/&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#00f&#34;&gt;async&lt;/span&gt; (req, res) =&amp;gt; {
3809&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; res.send(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;OK&amp;#39;&lt;/span&gt;);
3810&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;});
3811&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3812&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// return a 404 if no routes match
3813&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;app.use((req, res, next) =&amp;gt; {
3814&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; res.set(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;Cache-Control&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;private, no-store&amp;#39;&lt;/span&gt;);
3815&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; res.status(404).end(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;Not found&amp;#39;&lt;/span&gt;);
3816&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;});
3817&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3818&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// starts the server
3819&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;app.listen(port, () =&amp;gt; {
3820&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; console.log(&lt;span style=&#34;color:#a31515&#34;&gt;`PubSub server running on http://localhost:&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;${&lt;/span&gt;port&lt;span style=&#34;color:#a31515&#34;&gt;}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;`&lt;/span&gt;);
3821&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;});
3822&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h3 id=&#34;our-custom-message-format&#34;&gt;Our custom message format&lt;/h3&gt;
3823&lt;p&gt;Each message posted on a server must be in a specific format that out server
3824accepts. Having structure like this allows us to have multiple separated type of
3825events on each topic.&lt;/p&gt;
3826&lt;p&gt;With this we can separate streams and only receive events that belong to the
3827topic.&lt;/p&gt;
3828&lt;p&gt;One example would be, that we have index page and we want to receive messages
3829about new upvotes or new subscribers but we don&#39;t want to follow events for
3830other pages. This reduces clutter and overall network. And structure is much
3831nicer and maintanable.&lt;/p&gt;
3832&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;{
3833&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;topic&amp;#34;: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;sample-topic&amp;#34;&lt;/span&gt;,
3834&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;event&amp;#34;: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;sample-event&amp;#34;&lt;/span&gt;,
3835&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;message&amp;#34;: { &amp;#34;name&amp;#34;: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;John&amp;#34;&lt;/span&gt; }
3836&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
3837&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;publisher-and-subscriber-clients&#34;&gt;Publisher and subscriber clients&lt;/h2&gt;
3838&lt;h3 id=&#34;publisher-and-subscriber-in-action&#34;&gt;Publisher and subscriber in action&lt;/h3&gt;
3839&lt;p&gt;&lt;video src=&#34;/posts/simple-pubsub-server/clients.m4v&#34; controls&gt;&lt;/video&gt;&lt;/p&gt;
3840&lt;p&gt;You can download &lt;a href=&#34;../simple-pubsub-server/sse-pubsub-server.zip&#34;&gt;the code&lt;/a&gt; and
3841follow along.&lt;/p&gt;
3842&lt;h3 id=&#34;publisher&#34;&gt;Publisher&lt;/h3&gt;
3843&lt;p&gt;As talked about above publisher is the one that send messages to the
3844broker/server. Message inside the payload can be whatever you want (string,
3845object, array). I would however personally avoid send large chunks of data like
3846blobs and such.&lt;/p&gt;
3847&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;&amp;lt;!DOCTYPE html&amp;gt;&lt;/span&gt;
3848&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;lt;html lang=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;en&amp;#34;&lt;/span&gt;&amp;gt;
3849&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3850&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;head&amp;gt;
3851&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;meta charset=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;UTF-8&amp;#34;&lt;/span&gt;&amp;gt;
3852&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;meta name=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;viewport&amp;#34;&lt;/span&gt; content=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;width=device-width, initial-scale=1.0&amp;#34;&lt;/span&gt;&amp;gt;
3853&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;title&amp;gt;Publisher&amp;lt;/title&amp;gt;
3854&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/head&amp;gt;
3855&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3856&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;body&amp;gt;
3857&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3858&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;h1&amp;gt;Publisher&amp;lt;/h1&amp;gt;
3859&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3860&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;fieldset&amp;gt;
3861&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;p&amp;gt;
3862&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;label&amp;gt;Server:&amp;lt;/label&amp;gt;
3863&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;input type=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;text&amp;#34;&lt;/span&gt; id=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;server&amp;#34;&lt;/span&gt; value=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;http://localhost:4000&amp;#34;&lt;/span&gt;&amp;gt;
3864&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/p&amp;gt;
3865&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;p&amp;gt;
3866&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;label&amp;gt;Topic:&amp;lt;/label&amp;gt;
3867&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;input type=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;text&amp;#34;&lt;/span&gt; id=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;topic&amp;#34;&lt;/span&gt; value=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;sample-topic&amp;#34;&lt;/span&gt;&amp;gt;
3868&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/p&amp;gt;
3869&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;p&amp;gt;
3870&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;label&amp;gt;Event:&amp;lt;/label&amp;gt;
3871&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;input type=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;text&amp;#34;&lt;/span&gt; id=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;event&amp;#34;&lt;/span&gt; value=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;sample-event&amp;#34;&lt;/span&gt;&amp;gt;
3872&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/p&amp;gt;
3873&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;p&amp;gt;
3874&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;label&amp;gt;Message:&amp;lt;/label&amp;gt;
3875&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;input type=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;text&amp;#34;&lt;/span&gt; id=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;message&amp;#34;&lt;/span&gt; value=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;{&amp;#34;name&amp;#34;: &amp;#34;John&amp;#34;}&amp;#39;&lt;/span&gt;&amp;gt;
3876&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/p&amp;gt;
3877&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;p&amp;gt;
3878&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;button type=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;button&amp;#34;&lt;/span&gt; id=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;button&amp;#34;&lt;/span&gt;&amp;gt;Publish message to topic&amp;lt;/button&amp;gt;
3879&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/p&amp;gt;
3880&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/fieldset&amp;gt;
3881&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3882&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;script&amp;gt;
3883&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3884&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; button = document.querySelector(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;#button&amp;#39;&lt;/span&gt;);
3885&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; server = document.querySelector(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;#server&amp;#39;&lt;/span&gt;);
3886&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; topic = document.querySelector(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;#topic&amp;#39;&lt;/span&gt;);
3887&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; event = document.querySelector(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;#event&amp;#39;&lt;/span&gt;);
3888&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; message = document.querySelector(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;#message&amp;#39;&lt;/span&gt;);
3889&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3890&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; button.addEventListener(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;click&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#00f&#34;&gt;async&lt;/span&gt; (evt) =&amp;gt; {
3891&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; req = &lt;span style=&#34;color:#00f&#34;&gt;await&lt;/span&gt; fetch(&lt;span style=&#34;color:#a31515&#34;&gt;`&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;${&lt;/span&gt;server.value&lt;span style=&#34;color:#a31515&#34;&gt;}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;/publish`&lt;/span&gt;, {
3892&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; method: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;post&amp;#39;&lt;/span&gt;,
3893&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; headers: {
3894&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;Accept&amp;#39;&lt;/span&gt;: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;application/json&amp;#39;&lt;/span&gt;,
3895&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;Content-Type&amp;#39;&lt;/span&gt;: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;application/json&amp;#39;&lt;/span&gt;,
3896&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; },
3897&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; body: JSON.stringify({
3898&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; topic: topic.value,
3899&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; event: event.value,
3900&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; message: JSON.parse(message.value),
3901&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }),
3902&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; });
3903&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3904&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; res = &lt;span style=&#34;color:#00f&#34;&gt;await&lt;/span&gt; req.json();
3905&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; console.log(res);
3906&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; });
3907&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3908&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/script&amp;gt;
3909&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3910&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/body&amp;gt;
3911&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3912&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;lt;/html&amp;gt;
3913&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h3 id=&#34;subscriber&#34;&gt;Subscriber&lt;/h3&gt;
3914&lt;p&gt;Subscriber is responsible for receiving new messages that come from server via
3915publisher. The code bellow is very rudimentary but works and follows the
3916implementation guidelines for EventSource.&lt;/p&gt;
3917&lt;p&gt;You can use either Developer Tools Console to see incoming messages or you can
3918defer to Debugging with Google Chrome section above to see all EventStream
3919messages.&lt;/p&gt;
3920&lt;blockquote&gt;
3921&lt;p&gt;Don&#39;t be alarmed if the subscriber gets disconnected from the server every so
3922often. The code we have here resets connection every 15s but it automatically
3923get reconnected and fetches all messages up to last received message id. This
3924setting can be adjusted in &lt;code&gt;server.js&lt;/code&gt; file; search for the
3925&lt;code&gt;maxStreamDuration&lt;/code&gt; variable.&lt;/p&gt;
3926&lt;/blockquote&gt;
3927&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;&amp;lt;!DOCTYPE html&amp;gt;&lt;/span&gt;
3928&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;lt;html lang=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;en&amp;#34;&lt;/span&gt;&amp;gt;
3929&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3930&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;head&amp;gt;
3931&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;meta charset=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;UTF-8&amp;#34;&lt;/span&gt;&amp;gt;
3932&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;meta name=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;viewport&amp;#34;&lt;/span&gt; content=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;width=device-width, initial-scale=1.0&amp;#34;&lt;/span&gt;&amp;gt;
3933&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;title&amp;gt;Subscriber&amp;lt;/title&amp;gt;
3934&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;link rel=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;stylesheet&amp;#34;&lt;/span&gt; href=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;style.css&amp;#34;&lt;/span&gt;&amp;gt;
3935&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/head&amp;gt;
3936&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3937&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;body&amp;gt;
3938&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3939&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;h1&amp;gt;Subscriber&amp;lt;/h1&amp;gt;
3940&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3941&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;fieldset&amp;gt;
3942&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;p&amp;gt;
3943&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;label&amp;gt;Server:&amp;lt;/label&amp;gt;
3944&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;input type=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;text&amp;#34;&lt;/span&gt; id=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;server&amp;#34;&lt;/span&gt; value=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;http://localhost:4000&amp;#34;&lt;/span&gt;&amp;gt;
3945&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/p&amp;gt;
3946&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;p&amp;gt;
3947&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;label&amp;gt;Topic:&amp;lt;/label&amp;gt;
3948&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;input type=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;text&amp;#34;&lt;/span&gt; id=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;topic&amp;#34;&lt;/span&gt; value=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;sample-topic&amp;#34;&lt;/span&gt;&amp;gt;
3949&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/p&amp;gt;
3950&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;p&amp;gt;
3951&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;label&amp;gt;Event:&amp;lt;/label&amp;gt;
3952&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;input type=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;text&amp;#34;&lt;/span&gt; id=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;event&amp;#34;&lt;/span&gt; value=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;sample-event&amp;#34;&lt;/span&gt;&amp;gt;
3953&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/p&amp;gt;
3954&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;p&amp;gt;
3955&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;button type=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;button&amp;#34;&lt;/span&gt; id=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;button&amp;#34;&lt;/span&gt;&amp;gt;Subscribe to topic&amp;lt;/button&amp;gt;
3956&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/p&amp;gt;
3957&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/fieldset&amp;gt;
3958&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3959&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;script&amp;gt;
3960&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3961&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; button = document.querySelector(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;#button&amp;#39;&lt;/span&gt;);
3962&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; server = document.querySelector(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;#server&amp;#39;&lt;/span&gt;);
3963&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; topic = document.querySelector(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;#topic&amp;#39;&lt;/span&gt;);
3964&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;const&lt;/span&gt; event = document.querySelector(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;#event&amp;#39;&lt;/span&gt;);
3965&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3966&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; button.addEventListener(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;click&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#00f&#34;&gt;async&lt;/span&gt; (evt) =&amp;gt; {
3967&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3968&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;let&lt;/span&gt; es = &lt;span style=&#34;color:#00f&#34;&gt;new&lt;/span&gt; EventSource(&lt;span style=&#34;color:#a31515&#34;&gt;`&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;${&lt;/span&gt;server.value&lt;span style=&#34;color:#a31515&#34;&gt;}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;/stream/&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;${&lt;/span&gt;topic.value&lt;span style=&#34;color:#a31515&#34;&gt;}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;`&lt;/span&gt;);
3969&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3970&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; es.addEventListener(event.value, &lt;span style=&#34;color:#00f&#34;&gt;function&lt;/span&gt; (evt) {
3971&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; console.log(&lt;span style=&#34;color:#a31515&#34;&gt;`incoming message`&lt;/span&gt;, JSON.parse(evt.data));
3972&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; });
3973&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3974&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; es.addEventListener(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;open&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#00f&#34;&gt;function&lt;/span&gt; (evt) {
3975&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; console.log(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;connected&amp;#39;&lt;/span&gt;, evt);
3976&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; });
3977&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3978&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; es.addEventListener(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;error&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#00f&#34;&gt;function&lt;/span&gt; (evt) {
3979&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; console.log(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;error&amp;#39;&lt;/span&gt;, evt);
3980&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; });
3981&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3982&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; });
3983&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3984&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/script&amp;gt;
3985&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3986&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/body&amp;gt;
3987&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
3988&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;lt;/html&amp;gt;
3989&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;reading-further&#34;&gt;Reading further&lt;/h2&gt;
3990&lt;ul&gt;
3991&lt;li&gt;&lt;a href=&#34;https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events&#34;&gt;Using server-sent events&lt;/a&gt;&lt;/li&gt;
3992&lt;li&gt;&lt;a href=&#34;https://www.smashingmagazine.com/2018/02/sse-websockets-data-flow-http2/&#34;&gt;Using SSE Instead Of WebSockets For Unidirectional Data Flow Over HTTP/2&lt;/a&gt;&lt;/li&gt;
3993&lt;li&gt;&lt;a href=&#34;https://apifriends.com/api-streaming/server-sent-events/&#34;&gt;What is Server-Sent Events?&lt;/a&gt;&lt;/li&gt;
3994&lt;li&gt;&lt;a href=&#34;https://tools.ietf.org/id/draft-xie-bidirectional-messaging-01.html&#34;&gt;An HTTP/2 extension for bidirectional messaging communication&lt;/a&gt;&lt;/li&gt;
3995&lt;li&gt;&lt;a href=&#34;https://developers.google.com/web/fundamentals/performance/http2&#34;&gt;Introduction to HTTP/2&lt;/a&gt;&lt;/li&gt;
3996&lt;li&gt;&lt;a href=&#34;https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API&#34;&gt;The WebSocket API (WebSockets)&lt;/a&gt;&lt;/li&gt;
3997&lt;/ul&gt;
3998</content:encoded>
3999 </item>
4000
4001
4002
4003 <item>
4004 <title>Using sentiment analysis for clickbait detection in RSS feeds</title>
4005 <link>https://mitjafelicijan.com/using-sentiment-analysis-for-clickbait-detection-in-rss-feeds.html</link>
4006 <pubDate>Sat, 19 Oct 2019 12:00:00 &#43;0200</pubDate>
4007 <guid>https://mitjafelicijan.com/using-sentiment-analysis-for-clickbait-detection-in-rss-feeds.html</guid>
4008 <description>Initial thoughtsOne of the things that interested me for a while now is if major wellestablished news sites use click bait titles to drive additional traffic totheir sites and generate additional impressions.</description>
4009 <content:encoded>&lt;h2 id=&#34;initial-thoughts&#34;&gt;Initial thoughts&lt;/h2&gt;
4010&lt;p&gt;One of the things that interested me for a while now is if major well
4011established news sites use click bait titles to drive additional traffic to
4012their sites and generate additional impressions.&lt;/p&gt;
4013&lt;p&gt;Goal is to see how article titles and actual content of article differ from each
4014other and see if titles are clickbaited.&lt;/p&gt;
4015&lt;h2 id=&#34;preparing-and-cleaning-data&#34;&gt;Preparing and cleaning data&lt;/h2&gt;
4016&lt;p&gt;For this example I opted to just use RSS feed from a new website and decided to
4017go with &lt;a href=&#34;https://www.theguardian.com&#34;&gt;The Guardian&lt;/a&gt; World news. While this gets
4018us limited data (~40) articles and also description (actual content) is trimmed
4019this really doesn&#39;t reflect the actual article contents.&lt;/p&gt;
4020&lt;p&gt;To get better content I could use web scraping and use RSS as link list and
4021fetch contents directly from website, but for this simple example this will
4022suffice.&lt;/p&gt;
4023&lt;p&gt;There are couple of requirements we need to install before we continue:&lt;/p&gt;
4024&lt;ul&gt;
4025&lt;li&gt;&lt;code&gt;pip3 install feedparser&lt;/code&gt; (parses RSS feed from url)&lt;/li&gt;
4026&lt;li&gt;&lt;code&gt;pip3 install vaderSentiment&lt;/code&gt; (does sentiment polarity analysis)&lt;/li&gt;
4027&lt;li&gt;&lt;code&gt;pip3 install matplotlib&lt;/code&gt; (plots chart of results)&lt;/li&gt;
4028&lt;/ul&gt;
4029&lt;p&gt;So first we need to fetch RSS data and sanitize HTML content from description.&lt;/p&gt;
4030&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; re
4031&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; feedparser
4032&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4033&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;feed_url = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;https://www.theguardian.com/world/rss&amp;#34;&lt;/span&gt;
4034&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;feed = feedparser.parse(feed_url)
4035&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4036&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# sanitize html&lt;/span&gt;
4037&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; item &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; feed.entries:
4038&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; item.description = re.sub(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;&amp;lt;[^&amp;lt;]&#43;?&amp;gt;&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;&amp;#39;&lt;/span&gt;, item.description)
4039&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;perform-sentiment-analysis&#34;&gt;Perform sentiment analysis&lt;/h2&gt;
4040&lt;p&gt;Since we now have cleaned up data in our &lt;code&gt;feed.entries&lt;/code&gt; object we can start with
4041performing sentiment analysis.&lt;/p&gt;
4042&lt;p&gt;There are many sentiment analysis libraries available that range from rule-based
4043sentiment analysis up to machine learning supported analysis. To keep things
4044simple I decided to use rule-based analysis library
4045&lt;a href=&#34;https://github.com/cjhutto/vaderSentiment&#34;&gt;vaderSentiment&lt;/a&gt; from
4046&lt;a href=&#34;https://github.com/cjhutto&#34;&gt;C.J. Hutto&lt;/a&gt;. Really nice library and quite easy to
4047use.&lt;/p&gt;
4048&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;from&lt;/span&gt; vaderSentiment.vaderSentiment &lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; SentimentIntensityAnalyzer
4049&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;analyser = SentimentIntensityAnalyzer()
4050&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4051&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;sentiment_results = []
4052&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; item &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; feed.entries:
4053&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; sentiment_title = analyser.polarity_scores(item.title)
4054&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; sentiment_description = analyser.polarity_scores(item.description)
4055&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; sentiment_results.append([sentiment_title[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;compound&amp;#39;&lt;/span&gt;], sentiment_description[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;compound&amp;#39;&lt;/span&gt;]])
4056&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Now that we have this data in a shape that is compatible with matplotlib we can
4057plot results to see the difference between title and description sentiment of an
4058article.&lt;/p&gt;
4059&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; matplotlib.pyplot &lt;span style=&#34;color:#00f&#34;&gt;as&lt;/span&gt; plt
4060&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4061&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;plt.rcParams[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;figure.figsize&amp;#39;&lt;/span&gt;] = (15, 3)
4062&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;plt.plot(sentiment_results, drawstyle=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;steps&amp;#39;&lt;/span&gt;)
4063&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;plt.title(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;Sentiment analysis relationship between title and description (Guardian World News)&amp;#39;&lt;/span&gt;)
4064&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;plt.legend([&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;title&amp;#39;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;description&amp;#39;&lt;/span&gt;])
4065&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;plt.show()
4066&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;results-and-assets&#34;&gt;Results and assets&lt;/h2&gt;
4067&lt;ol&gt;
4068&lt;li&gt;Because of the small sample size further conclusions are impossible to make.&lt;/li&gt;
4069&lt;li&gt;Rule-based approach may not be the best way of doing this. By using deep
4070learning we would be able to get better insights.&lt;/li&gt;
4071&lt;li&gt;&lt;strong&gt;Next step would be to&lt;/strong&gt; periodically fetch RSS items and store them over a
4072longer period of time and then perform analysis again and use either machine
4073learning or deep learning on top of it.&lt;/li&gt;
4074&lt;/ol&gt;
4075&lt;figure&gt;
4076&lt;img src=&#34;/posts/sentiment-analysis/guardian-sa-title-desc-relationship.png&#34; alt=&#34;Relationship between title and description&#34; /&gt;
4077&lt;/figure&gt;
4078&lt;p&gt;Figure above displays difference between title and description sentiment for
4079specific RSS feed item. 1 means positive and -1 means negative sentiment.&lt;/p&gt;
4080&lt;p&gt;&lt;a href=&#34;/posts/sentiment-analysis/sentiment-analysis.ipynb&#34;&gt;» Download Jupyter Notebook&lt;/a&gt;&lt;/p&gt;
4081&lt;h2 id=&#34;going-further&#34;&gt;Going further&lt;/h2&gt;
4082&lt;ul&gt;
4083&lt;li&gt;&lt;a href=&#34;https://github.com/bswiss/news_mood&#34;&gt;Twitter Sentiment Analysis by Bryan Schwierzke&lt;/a&gt;&lt;/li&gt;
4084&lt;li&gt;&lt;a href=&#34;https://github.com/thisandagain/sentiment&#34;&gt;AFINN-based sentiment analysis for Node.js by Andrew Sliwinski&lt;/a&gt;&lt;/li&gt;
4085&lt;li&gt;&lt;a href=&#34;https://github.com/adeshpande3/LSTM-Sentiment-Analysis&#34;&gt;Sentiment Analysis with LSTMs in Tensorflow by Adit Deshpande&lt;/a&gt;&lt;/li&gt;
4086&lt;li&gt;&lt;a href=&#34;https://github.com/abdulfatir/twitter-sentiment-analysis&#34;&gt;Sentiment analysis on tweets using Naive Bayes, SVM, CNN, LSTM, etc. by Abdul Fatir&lt;/a&gt;&lt;/li&gt;
4087&lt;/ul&gt;
4088</content:encoded>
4089 </item>
4090
4091
4092
4093 <item>
4094 <title>Simplifying and reducing clutter in my life and work</title>
4095 <link>https://mitjafelicijan.com/simplifying-and-reducing-clutter.html</link>
4096 <pubDate>Mon, 14 Oct 2019 12:00:00 &#43;0200</pubDate>
4097 <guid>https://mitjafelicijan.com/simplifying-and-reducing-clutter.html</guid>
4098 <description>I recently moved my main working machine back from Hachintosh to Linux.</description>
4099 <content:encoded>&lt;p&gt;I recently moved my main working machine back from Hachintosh to Linux. Well the
4100experiment was interesting and I have done some great work on macOS but it was
4101time to move back.&lt;/p&gt;
4102&lt;p&gt;I actually really missed Linux. The simplicity of &lt;code&gt;apt-get&lt;/code&gt; or just the amount
4103of software that exists for Linux should be a no-brainer. I spent most of my
4104time on macOS finding solutions to make things work. Using
4105&lt;a href=&#34;https://brew.sh/&#34;&gt;Brew&lt;/a&gt; was just a horrible experience and far from package
4106managers of Linux. At least they managed to get that &lt;code&gt;sudo&lt;/code&gt; debacle sorted.&lt;/p&gt;
4107&lt;p&gt;Not all was bad. macOS in general was a perfectly good environment. Things like
4108Docker and tooling like this worked without any hiccups. My normal tools like
4109coding IDE worked flawlessly and the whole look and feel is just superb. I have
4110been using MacBook Air for couple of years so I was used to the system but never
4111as a daily driver.&lt;/p&gt;
4112&lt;p&gt;One of the things I did after I installed Linux back on my machine was cleaning
4113up my Dropbox folder. I have everything on Dropbox. Even projects folder. I
4114write code for living so my whole life revolves around couple of megs of code
4115(with assets). So it&#39;s not like I have huge files on my machine. I don&#39;t have
4116movies or music or pictures on my PC. All of that stuff is in cloud. I use
4117Google music and I have Netflix account which is more than enough for me.&lt;/p&gt;
4118&lt;p&gt;I also went and deleted some of the repositories on my Github account. I have
4119deleted more code than deployed. People find this strange but for me deleting
4120something feels so cathartic and also forces me to write better code next time
4121around when I am faced with similar problem. That was a huge relief if I am
4122being totally honest.&lt;/p&gt;
4123&lt;p&gt;Next step was to do something with my webpage. I have been using some scripts I
4124wrote a while ago to generate static pages from markdown source posts. I kept on
4125adding and adding stuff on top of it and it became a source of a
4126frustration. And this is just a simple blog and I was using gulp and npm.
4127Anyways after couple of hours of searching and testing static generators I found
4128an interesting one
4129&lt;a href=&#34;https://github.com/piranha/gostatic&#34;&gt;https://github.com/piranha/gostatic&lt;/a&gt; and I
4130just decided to use this one. It was the only one that had a simple templating
4131engine, not that I really need one. But others had this convoluted way of trying
4132to solve everything and at the end just required quite bigger learning curve I
4133was ready to go with. So I deleted couple of old posts, simplified HTML, trashed
4134most of the CSS and went with
4135&lt;a href=&#34;https://motherfuckingwebsite.com/&#34;&gt;https://motherfuckingwebsite.com/&lt;/a&gt;
4136aesthetics. Yeah, the previous site was more visually stimulating but all I
4137really care is the content at this point. And Times New Roman font is kind of
4138awesome.&lt;/p&gt;
4139&lt;p&gt;I stopped working on most of the projects in the past couple of months because
4140the overhead was just too insane. There comes a point when you stretch yourself
4141too much and then you stop progressing and with that comes dissatisfaction.&lt;/p&gt;
4142&lt;p&gt;So that&#39;s about it. Moving forward minimal style.&lt;/p&gt;
4143</content:encoded>
4144 </item>
4145
4146
4147
4148 <item>
4149 <title>Encoding binary data into DNA sequence</title>
4150 <link>https://mitjafelicijan.com/encoding-binary-data-into-dna-sequence.html</link>
4151 <pubDate>Thu, 03 Jan 2019 12:00:00 &#43;0200</pubDate>
4152 <guid>https://mitjafelicijan.com/encoding-binary-data-into-dna-sequence.html</guid>
4153 <description>Initial thoughtsImagine a world where you could go outside and take a leaf from a tree and putit through your personal DNA sequencer and get data like music, videos orcomputer programs from it.</description>
4154 <content:encoded>&lt;h2 id=&#34;initial-thoughts&#34;&gt;Initial thoughts&lt;/h2&gt;
4155&lt;p&gt;Imagine a world where you could go outside and take a leaf from a tree and put
4156it through your personal DNA sequencer and get data like music, videos or
4157computer programs from it. Well, this is all possible now. It was not done on a
4158large scale because it is quite expensive to create DNA strands but it&#39;s
4159possible.&lt;/p&gt;
4160&lt;p&gt;Encoding data into DNA sequence is relatively simple process once you understand
4161the relationship between binary data and nucleotides and scientists have been
4162making large leaps in this field in order to provide viable long-term storage
4163solution for our data that would potentially survive our specie if case of
4164global disaster. We could imprint all the world&#39;s knowledge into plants and
4165ensure the survival of our knowledge.&lt;/p&gt;
4166&lt;p&gt;More optimistic usage for this technology would be easier storage of ever
4167growing data we produce every day. Once machines for sequencing DNA become fast
4168enough and cheaper this could mean the next evolution of storing data and
4169abandoning classical hard and solid state drives in data warehouses.&lt;/p&gt;
4170&lt;p&gt;As we currently stand this is still not viable but it is quite an amazing and
4171cool technology.&lt;/p&gt;
4172&lt;p&gt;My interests in this field are purely in encoding processes and experimental
4173testing mainly because I don&#39;t have the access to this expensive machines. My
4174initial goal was to create a toolkit that can be used by everybody to encode
4175their data into a proper DNA sequence.&lt;/p&gt;
4176&lt;h2 id=&#34;glossary&#34;&gt;Glossary&lt;/h2&gt;
4177&lt;p&gt;&lt;strong&gt;deoxyribose&lt;/strong&gt; A five-carbon sugar molecule with a hydrogen atom rather than a
4178hydroxyl group in the 2′ position; the sugar component of DNA nucleotides.&lt;/p&gt;
4179&lt;p&gt;&lt;strong&gt;double helix&lt;/strong&gt; The molecular shape of DNA in which two strands of nucleotides
4180wind around each other in a spiral shape.&lt;/p&gt;
4181&lt;p&gt;&lt;strong&gt;nitrogenous base&lt;/strong&gt; A nitrogen-containing molecule that acts as a base; often
4182referring to one of the purine or pyrimidine components of nucleic acids.&lt;/p&gt;
4183&lt;p&gt;&lt;strong&gt;phosphate group&lt;/strong&gt; A molecular group consisting of a central phosphorus atom
4184bound to four oxygen atoms.&lt;/p&gt;
4185&lt;p&gt;&lt;strong&gt;RGB&lt;/strong&gt; The RGB color model is an additive color model in which red, green and
4186blue light are added together in various ways to reproduce a broad array of
4187colors.&lt;/p&gt;
4188&lt;p&gt;&lt;strong&gt;GCC&lt;/strong&gt; The GNU Compiler Collection is a compiler system produced by the GNU
4189Project supporting various programming languages.&lt;/p&gt;
4190&lt;h2 id=&#34;data-encoding&#34;&gt;Data encoding&lt;/h2&gt;
4191&lt;p&gt;&lt;strong&gt;TL;DR:&lt;/strong&gt; Encoding involves the use of a code to change original data into a
4192form that can be used by an external process.&lt;/p&gt;
4193&lt;p&gt;Encoding is the process of converting data into a format required for a number
4194of information processing needs, including:&lt;/p&gt;
4195&lt;ul&gt;
4196&lt;li&gt;Program compiling and execution&lt;/li&gt;
4197&lt;li&gt;Data transmission, storage and compression/decompression&lt;/li&gt;
4198&lt;li&gt;Application data processing, such as file conversion&lt;/li&gt;
4199&lt;/ul&gt;
4200&lt;p&gt;Encoding can have two meanings:&lt;/p&gt;
4201&lt;ul&gt;
4202&lt;li&gt;In computer technology, encoding is the process of applying a specific code,
4203such as letters, symbols and numbers, to data for conversion into an
4204equivalent cipher.&lt;/li&gt;
4205&lt;li&gt;In electronics, encoding refers to analog to digital conversion.&lt;/li&gt;
4206&lt;/ul&gt;
4207&lt;h2 id=&#34;quick-history-of-dna&#34;&gt;Quick history of DNA&lt;/h2&gt;
4208&lt;ul&gt;
4209&lt;li&gt;&lt;strong&gt;1869&lt;/strong&gt; - Friedrich Miescher identifies &amp;quot;nuclein&amp;quot;.&lt;/li&gt;
4210&lt;li&gt;&lt;strong&gt;1900s&lt;/strong&gt; - The Eugenics Movement.&lt;/li&gt;
4211&lt;li&gt;&lt;strong&gt;1900&lt;/strong&gt; – Mendel&#39;s theories are rediscovered by researchers.&lt;/li&gt;
4212&lt;li&gt;&lt;strong&gt;1944&lt;/strong&gt; - Oswald Avery identifies DNA as the &#39;transforming principle&#39;.&lt;/li&gt;
4213&lt;li&gt;&lt;strong&gt;1952&lt;/strong&gt; - Rosalind Franklin photographs crystallized DNA fibres.&lt;/li&gt;
4214&lt;li&gt;&lt;strong&gt;1953&lt;/strong&gt; - James Watson and Francis Crick discover the double helix structure of DNA.&lt;/li&gt;
4215&lt;li&gt;&lt;strong&gt;1965&lt;/strong&gt; - Marshall Nirenberg is the first person to sequence the bases in each codon.&lt;/li&gt;
4216&lt;li&gt;&lt;strong&gt;1983&lt;/strong&gt; - Huntington&#39;s disease is the first mapped genetic disease.&lt;/li&gt;
4217&lt;li&gt;&lt;strong&gt;1990&lt;/strong&gt; - The Human Genome Project begins.&lt;/li&gt;
4218&lt;li&gt;&lt;strong&gt;1995&lt;/strong&gt; - Haemophilus Influenzae is the first bacterium genome sequenced.&lt;/li&gt;
4219&lt;li&gt;&lt;strong&gt;1996&lt;/strong&gt; - Dolly the sheep is cloned.&lt;/li&gt;
4220&lt;li&gt;&lt;strong&gt;1999&lt;/strong&gt; - First human chromosome is decoded.&lt;/li&gt;
4221&lt;li&gt;&lt;strong&gt;2000&lt;/strong&gt; – Genetic code of the fruit fly is decoded.&lt;/li&gt;
4222&lt;li&gt;&lt;strong&gt;2002&lt;/strong&gt; – Mouse is the first mammal to have its genome decoded.&lt;/li&gt;
4223&lt;li&gt;&lt;strong&gt;2003&lt;/strong&gt; – The Human Genome Project is completed.&lt;/li&gt;
4224&lt;li&gt;&lt;strong&gt;2013&lt;/strong&gt; – DNA Worldwide and Eurofins Forensic discover identical twins have differences in their genetic makeup.&lt;/li&gt;
4225&lt;/ul&gt;
4226&lt;h2 id=&#34;what-is-dna&#34;&gt;What is DNA?&lt;/h2&gt;
4227&lt;p&gt;Deoxyribonucleic acid, a self-replicating material which is &lt;strong&gt;present in nearly
4228all living organisms&lt;/strong&gt; as the main constituent of chromosomes. It is the
4229&lt;strong&gt;carrier of genetic information&lt;/strong&gt;.&lt;/p&gt;
4230&lt;blockquote&gt;
4231&lt;p&gt;The nitrogen in our DNA, the calcium in our teeth, the iron in our blood,
4232the carbon in our apple pies were made in the interiors of collapsing stars.
4233We are made of starstuff.
4234&lt;strong&gt;-- Carl Sagan, Cosmos&lt;/strong&gt;&lt;/p&gt;
4235&lt;/blockquote&gt;
4236&lt;p&gt;The nucleotide in DNA consists of a sugar (deoxyribose), one of four bases
4237(cytosine (C), thymine (T), adenine (A), guanine (G)), and a phosphate.
4238Cytosine and thymine are pyrimidine bases, while adenine and guanine are purine
4239bases. The sugar and the base together are called a nucleoside.&lt;/p&gt;
4240&lt;figure&gt;
4241&lt;img src=&#34;/posts/dna-sequence/dna-basics.jpg&#34; alt=&#34;DNA&#34; /&gt;
4242&lt;figcaption&gt;&lt;p&gt;&lt;em&gt;DNA (a) forms a double stranded helix, and (b) adenine pairs with thymine and
4243cytosine pairs with guanine. (credit a: modification of work by Jerome Walker,
4244Dennis Myts)&lt;/em&gt;&lt;/p&gt;&lt;/figcaption&gt;
4245&lt;/figure&gt;
4246&lt;h2 id=&#34;encode-binary-data-into-dna-sequence&#34;&gt;Encode binary data into DNA sequence&lt;/h2&gt;
4247&lt;p&gt;As an input file you can use any file you want:&lt;/p&gt;
4248&lt;ul&gt;
4249&lt;li&gt;ASCII files,&lt;/li&gt;
4250&lt;li&gt;Compiled programs,&lt;/li&gt;
4251&lt;li&gt;Multimedia files (MP3, MP4, MVK, etc),&lt;/li&gt;
4252&lt;li&gt;Images,&lt;/li&gt;
4253&lt;li&gt;Database files,&lt;/li&gt;
4254&lt;li&gt;etc.&lt;/li&gt;
4255&lt;/ul&gt;
4256&lt;p&gt;Note: If you would copy all the bytes from RAM to file or pipe data to file you
4257could encode also this data as long as you provide file pointer to the encoder.&lt;/p&gt;
4258&lt;h3 id=&#34;basic-encoding&#34;&gt;Basic Encoding&lt;/h3&gt;
4259&lt;p&gt;As already mentioned, the Basic Encoding is based on a simple mapping. Since DNA
4260is composed of 4 nucleotides (Adenine, Cytosine, Guanine, Thymine; usually
4261referred using the first letter). Using this technique we can encode&lt;/p&gt;
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4263&lt;p&gt;using a single nucleotide. In this way, we are able to use the 4 bases that
4264compose the DNA strand to encode each byte of data.&lt;/p&gt;
4265&lt;table&gt;
4266&lt;thead&gt;
4267&lt;tr&gt;
4268&lt;th&gt;Two bits&lt;/th&gt;
4269&lt;th&gt;Nucleotides&lt;/th&gt;
4270&lt;/tr&gt;
4271&lt;/thead&gt;
4272&lt;tbody&gt;
4273&lt;tr&gt;
4274&lt;td&gt;00&lt;/td&gt;
4275&lt;td&gt;&lt;strong&gt;A&lt;/strong&gt; (Adenine)&lt;/td&gt;
4276&lt;/tr&gt;
4277&lt;tr&gt;
4278&lt;td&gt;10&lt;/td&gt;
4279&lt;td&gt;&lt;strong&gt;G&lt;/strong&gt; (Guanine)&lt;/td&gt;
4280&lt;/tr&gt;
4281&lt;tr&gt;
4282&lt;td&gt;01&lt;/td&gt;
4283&lt;td&gt;&lt;strong&gt;C&lt;/strong&gt; (Cytosine)&lt;/td&gt;
4284&lt;/tr&gt;
4285&lt;tr&gt;
4286&lt;td&gt;11&lt;/td&gt;
4287&lt;td&gt;&lt;strong&gt;T&lt;/strong&gt; (Thymine)&lt;/td&gt;
4288&lt;/tr&gt;
4289&lt;/tbody&gt;
4290&lt;/table&gt;
4291&lt;p&gt;With this in mind we can simply encode any data by using two-bit to Nucleotides
4292conversion.&lt;/p&gt;
4293&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;{ Algorithm 1: Naive byte array to DNA encode }
4294&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;procedure EncodeToDNASequence(f) string
4295&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;begin
4296&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; enc string
4297&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;while&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;not&lt;/span&gt; eof(f) do
4298&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; c byte := buffer[0] { Read 1 byte &lt;span style=&#34;color:#00f&#34;&gt;from&lt;/span&gt; buffer }
4299&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; bin integer := sprintf(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;08b&amp;#39;&lt;/span&gt;, c) { Convert to string binary }
4300&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; e &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; range[0, 2, 4, 6] do
4301&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; e[0] == 48 &lt;span style=&#34;color:#00f&#34;&gt;and&lt;/span&gt; e[1] == 48 then { 0x00 - A (Adenine) }
4302&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; enc &#43;= &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;A&amp;#39;&lt;/span&gt;
4303&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;else&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; e[0] == 48 &lt;span style=&#34;color:#00f&#34;&gt;and&lt;/span&gt; e[1] == 49 then { 0x01 - G (Guanine) }
4304&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; enc &#43;= &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;G&amp;#39;&lt;/span&gt;
4305&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;else&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; e[0] == 49 &lt;span style=&#34;color:#00f&#34;&gt;and&lt;/span&gt; e[1] == 48 then { 0x10 - C (Cytosine) }
4306&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; enc &#43;= &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;C&amp;#39;&lt;/span&gt;
4307&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;else&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; e[0] == 49 &lt;span style=&#34;color:#00f&#34;&gt;and&lt;/span&gt; e[1] == 49 then { 0x11 - T (Thymine) }
4308&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; enc &#43;= &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;T&amp;#39;&lt;/span&gt;
4309&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt; enc { Return DNA sequence }
4310&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;end
4311&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Another encoding would be &lt;strong&gt;Goldman encoding&lt;/strong&gt;. Using this encoding helps with
4312Nonsense mutation (amino acids replaced by a stop codon) that occurs and is the
4313most problematic during translation because it leads to truncated amino acid
4314sequences, which in turn results in truncated proteins.&lt;/p&gt;
4315&lt;p&gt;&lt;a href=&#34;https://www.youtube.com/watch?v=a4PiGWNsIEU&#34;&gt;Where to store big data? In DNA: Nick Goldman at TEDxPrague&lt;/a&gt;&lt;/p&gt;
4316&lt;h3 id=&#34;fasta-file-format&#34;&gt;FASTA file format&lt;/h3&gt;
4317&lt;p&gt;In bioinformatics, FASTA format is a text-based format for representing either
4318nucleotide sequences or peptide sequences, in which nucleotides or amino acids
4319are represented using single-letter codes. The format also allows for sequence
4320names and comments to precede the sequences. The format originates from the
4321FASTA software package, but has now become a standard in the field of
4322bioinformatics.&lt;/p&gt;
4323&lt;p&gt;The first line in a FASTA file started either with a &amp;quot;&amp;gt;&amp;quot; (greater-than) symbol
4324or, less frequently, a &amp;quot;;&amp;quot; (semicolon) was taken as a comment. Subsequent lines
4325starting with a semicolon would be ignored by software. Since the only comment
4326used was the first, it quickly became used to hold a summary description of the
4327sequence, often starting with a unique library accession number, and with time
4328it has become commonplace to always use &amp;quot;&amp;gt;&amp;quot; for the first line and to not use
4329&amp;quot;;&amp;quot; comments (which would otherwise be ignored).&lt;/p&gt;
4330&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;;LCBO - Prolactin precursor - Bovine
4331&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;; a sample sequence in FASTA format
4332&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;MDSKGSSQKGSRLLLLLVVSNLLLCQGVVSTPVCPNGPGNCQVSLRDLFDRAVMVSHYIHDLSS
4333&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;EMFNEFDKRYAQGKGFITMALNSCHTSSLPTPEDKEQAQQTHHEVLMSLILGLLRSWNDPLYHL
4334&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;VTEVRGMKGAPDAILSRAIEIEEENKRLLEGMEMIFGQVIPGAKETEPYPVWSGLPSLQTKDED
4335&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ARYSAFYNLLHCLRRDSSKIDTYLKLLNCRIIYNNNC*
4336&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4337&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;gt;MCHU - Calmodulin - Human, rabbit, bovine, rat, and chicken
4338&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ADQLTEEQIAEFKEAFSLFDKDGDGTITTKELGTVMRSLGQNPTEAELQDMINEVDADGNGTID
4339&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;FPEFLTMMARKMKDTDSEEEIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDEEVDEMIREA
4340&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;DIDGDGQVNYEEFVQMMTAK*
4341&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4342&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;gt;gi|5524211|gb|AAD44166.1| cytochrome b [Elephas maximus maximus]
4343&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;LCLYTHIGRNIYYGSYLYSETWNTGIMLLLITMATAFMGYVLPWGQMSFWGATVITNLFSAIPYIGTNLV
4344&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;EWIWGGFSVDKATLNRFFAFHFILPFTMVALAGVHLTFLHETGSNNPLGLTSDSDKIPFHPYYTIKDFLG
4345&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;LLILILLLLLLALLSPDMLGDPDNHMPADPLNTPLHIKPEWYFLFAYAILRSVPNKLGGVLALFLSIVIL
4346&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;GLMPFLHTSKHRSMMLRPLSQALFWTLTMDLLTLTWIGSQPVEYPYTIIGQMASILYFSIILAFLPIAGX
4347&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;IENY
4348&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;FASTA format was extended by &lt;a href=&#34;https://en.wikipedia.org/wiki/FASTQ_format&#34;&gt;FASTQ&lt;/a&gt;
4349format from the &lt;a href=&#34;https://www.sanger.ac.uk/&#34;&gt;Sanger Centre&lt;/a&gt; in Cambridge.&lt;/p&gt;
4350&lt;h3 id=&#34;png-encoded-dna-sequence&#34;&gt;PNG encoded DNA sequence&lt;/h3&gt;
4351&lt;table&gt;
4352&lt;thead&gt;
4353&lt;tr&gt;
4354&lt;th&gt;Nucleotides&lt;/th&gt;
4355&lt;th&gt;RGB&lt;/th&gt;
4356&lt;th&gt;Color name&lt;/th&gt;
4357&lt;/tr&gt;
4358&lt;/thead&gt;
4359&lt;tbody&gt;
4360&lt;tr&gt;
4361&lt;td&gt;A ➞ Adenine&lt;/td&gt;
4362&lt;td&gt;(0,0,255)&lt;/td&gt;
4363&lt;td&gt;Blue&lt;/td&gt;
4364&lt;/tr&gt;
4365&lt;tr&gt;
4366&lt;td&gt;G ➞ Guanine&lt;/td&gt;
4367&lt;td&gt;(0,100,0)&lt;/td&gt;
4368&lt;td&gt;Green&lt;/td&gt;
4369&lt;/tr&gt;
4370&lt;tr&gt;
4371&lt;td&gt;C ➞ Cytosine&lt;/td&gt;
4372&lt;td&gt;(255,0,0)&lt;/td&gt;
4373&lt;td&gt;Red&lt;/td&gt;
4374&lt;/tr&gt;
4375&lt;tr&gt;
4376&lt;td&gt;T ➞ Thymine&lt;/td&gt;
4377&lt;td&gt;(255,255,0)&lt;/td&gt;
4378&lt;td&gt;Yellow&lt;/td&gt;
4379&lt;/tr&gt;
4380&lt;/tbody&gt;
4381&lt;/table&gt;
4382&lt;p&gt;With this in mind we can create a simple algorithm to create PNG representation
4383of a DNA sequence.&lt;/p&gt;
4384&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;{ Algorithm 2: Naive DNA to PNG encode &lt;span style=&#34;color:#00f&#34;&gt;from&lt;/span&gt; FASTA file }
4385&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;procedure EncodeDNASequenceToPNG(f)
4386&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;begin
4387&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; i image
4388&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;while&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;not&lt;/span&gt; eof(f) do
4389&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; c char := buffer[0] { Read 1 char &lt;span style=&#34;color:#00f&#34;&gt;from&lt;/span&gt; buffer }
4390&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; case c of
4391&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;A&amp;#39;&lt;/span&gt;: color := RGB(0, 0, 255) { Blue }
4392&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;G&amp;#39;&lt;/span&gt;: color := RGB(0, 100, 0) { Green }
4393&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;C&amp;#39;&lt;/span&gt;: color := RGB(255, 0, 0) { Red }
4394&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;T&amp;#39;&lt;/span&gt;: color := RGB(255, 255, 0) { Yellow }
4395&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; drawRect(i, [x, y], color)
4396&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; save(i) { Save PNG image }
4397&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;end
4398&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;encoding-text-file-in-practice&#34;&gt;Encoding text file in practice&lt;/h2&gt;
4399&lt;p&gt;In this example we will take a simple text file as our input stream for
4400encoding. This file will have a quote from Niels Bohr and saved as txt file.&lt;/p&gt;
4401&lt;blockquote&gt;
4402&lt;p&gt;How wonderful that we have met with a paradox. Now we have some hope of
4403making progress.
4404― Niels Bohr&lt;/p&gt;
4405&lt;/blockquote&gt;
4406&lt;p&gt;First we encode text file into FASTA file.&lt;/p&gt;
4407&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;./dnae-encode -i quote.txt -o quote.fa
4408&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;2019/01/10 00:38:29 Gathering input file stats
4409&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;2019/01/10 00:38:29 Starting encoding ...
4410&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; 106 B / 106 B [==================================] 100.00% 0s
4411&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;2019/01/10 00:38:29 Saving to FASTA file ...
4412&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;2019/01/10 00:38:29 Output FASTA file length is 438 B
4413&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;2019/01/10 00:38:29 Process took 987.263µs
4414&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;2019/01/10 00:38:29 Done ...
4415&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Output of &lt;code&gt;quote.fa&lt;/code&gt; file contains the encoded DNA sequence in ASCII format.&lt;/p&gt;
4416&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;gt;SEQ1
4417&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;GACAGCTTGTGTACAAGTGTGCTTGCTCGCGAGCGGGTACGCGCGTGGGCTAACAAGTGA
4418&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;GCCAGCAGGTGAACAAGTGTGCGGACAAGCCAGCAGGTGCGCGGACAAGCTGGCGGGTGA
4419&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ACAAGTGTGCCGGTGAGCCAACAAGCAGACAAGTAAGCAGGTACGCAGGCGAGCTTGTCA
4420&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ACTCACAAGATCGCTTGTGTACAAGTGTGCGGACAAGCCAGCAGGTGCGCGGACAAGTAT
4421&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;GCTTGCTGGCGGACAAGCCAGCTTGTAAGCGGACAAGCTTGCGCACAAGCTGGCAGGCCT
4422&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;GCCGGCTCGCGTACAAATTCACAAGTAAGTACGCTTGCGTGTACGCGGGTATGTATACTC
4423&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;AACCTCACCAAACGGGACAAGATCGCCGGCGGGCTAGTATACAAGAACGCTTGCCAGTAC
4424&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;AACC
4425&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Then we encode FASTA file from previous operation to encode this data into PNG.&lt;/p&gt;
4426&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;./dnae-png -i quote.fa -o quote.png
4427&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;2019/01/10 00:40:09 Gathering input file stats ...
4428&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;2019/01/10 00:40:09 Deconstructing FASTA file ...
4429&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;2019/01/10 00:40:09 Compositing image file ...
4430&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; 424 / 424 [==================================] 100.00% 0s
4431&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;2019/01/10 00:40:09 Saving output file ...
4432&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;2019/01/10 00:40:09 Output image file length is 1.1 kB
4433&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;2019/01/10 00:40:09 Process took 19.036117ms
4434&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;2019/01/10 00:40:09 Done ...
4435&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;After encoding into PNG format this file looks like this.&lt;/p&gt;
4436&lt;figure&gt;
4437&lt;img src=&#34;/posts/dna-sequence/quote.png&#34; alt=&#34;Encoded Quote in PNG format&#34; /&gt;
4438&lt;figcaption&gt;&lt;p&gt;The larger the input stream is the larger the PNG file would be.&lt;/p&gt;&lt;/figcaption&gt;
4439&lt;/figure&gt;
4440&lt;p&gt;Compiled basic Hello World C program with
4441&lt;a href=&#34;https://www.gnu.org/software/gcc/&#34;&gt;GCC&lt;/a&gt; would &lt;a href=&#34;/posts/dna-sequence/sample.png&#34;&gt;look
4442like&lt;/a&gt;.&lt;/p&gt;
4443&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// gcc -O3 -o sample sample.c
4444&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;#include&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;&amp;lt;stdio.h&amp;gt;&lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;
4445&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;&lt;/span&gt;
4446&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;main() {
4447&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; printf(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Hello, world!&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\n&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt;);
4448&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt; 0;
4449&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
4450&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;toolkit-for-encoding-data&#34;&gt;Toolkit for encoding data&lt;/h2&gt;
4451&lt;p&gt;I have created a toolkit with two main programs:&lt;/p&gt;
4452&lt;ul&gt;
4453&lt;li&gt;dnae-encode (encodes file into FASTA file)&lt;/li&gt;
4454&lt;li&gt;dnae-png (encodes FASTA file into PNG)&lt;/li&gt;
4455&lt;/ul&gt;
4456&lt;p&gt;Toolkit with full source code is available on
4457&lt;a href=&#34;https://github.com/mitjafelicijan/dna-encoding&#34;&gt;github.com/mitjafelicijan/dna-encoding&lt;/a&gt;.&lt;/p&gt;
4458&lt;h3 id=&#34;dnae-encode&#34;&gt;dnae-encode&lt;/h3&gt;
4459&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;gt; ./dnae-encode --help
4460&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;usage: dnae-encode --input=INPUT [&amp;lt;flags&amp;gt;]
4461&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4462&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;A command-line application that encodes file into DNA sequence.
4463&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4464&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Flags:
4465&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; --help Show context-sensitive help (also try --help-long and --help-man).
4466&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; -i, --input=INPUT Input file (ASCII or binary) which will be encoded into DNA sequence.
4467&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; -o, --output=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;out.fa&amp;#34;&lt;/span&gt; Output file which stores DNA sequence in FASTA format.
4468&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; -s, --sequence=SEQ1 The description line (defline) or header/identifier line, gives a name and/or a unique identifier &lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; the sequence.
4469&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; -c, --columns=60 Row characters length (no more than 120 characters). Devices preallocate fixed line sizes in software.
4470&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; --version Show application version.
4471&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h3 id=&#34;dnae-png&#34;&gt;dnae-png&lt;/h3&gt;
4472&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;gt; ./dnae-png --help
4473&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;usage: dnae-png --input=INPUT [&amp;lt;flags&amp;gt;]
4474&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4475&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;A command-line application that encodes FASTA file into PNG image.
4476&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4477&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;Flags:
4478&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; --help Show context-sensitive help (also try --help-long and --help-man).
4479&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; -i, --input=INPUT Input FASTA file which will be encoded into PNG image.
4480&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; -o, --output=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;out.png&amp;#34;&lt;/span&gt; Output file in PNG format that represents DNA sequence in graphical way.
4481&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; -s, --size=10 Size of pairings of DNA bases on image in pixels (lower resolution lower file size).
4482&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; --version Show application version.
4483&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h2 id=&#34;benchmarks&#34;&gt;Benchmarks&lt;/h2&gt;
4484&lt;p&gt;First we generate some binary sample data with dd.&lt;/p&gt;
4485&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;dd &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt;=&amp;lt;(openssl enc -aes-256-ctr -pass pass:&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;$(&lt;/span&gt;dd &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt;=/dev/urandom bs=128 count=1 2&amp;gt;/dev/null | base64&lt;span style=&#34;color:#00f&#34;&gt;)&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt; -nosalt &amp;lt; /dev/zero) of=1KB.bin bs=1KB count=1 iflag=fullblock
4486&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;figure&gt;
4487&lt;img src=&#34;/posts/dna-sequence/sample-binary-file.png&#34; alt=&#34;Sample binary file 1KB&#34; /&gt;
4488&lt;figcaption&gt;&lt;p&gt;Our freshly generated 1KB file looks something like this (its full of
4489garbage data as intended).&lt;/p&gt;&lt;/figcaption&gt;
4490&lt;/figure&gt;
4491&lt;p&gt;We create following binary files:&lt;/p&gt;
4492&lt;ul&gt;
4493&lt;li&gt;1KB.bin&lt;/li&gt;
4494&lt;li&gt;10KB.bin&lt;/li&gt;
4495&lt;li&gt;100KB.bin&lt;/li&gt;
4496&lt;li&gt;1MB.bin&lt;/li&gt;
4497&lt;li&gt;10MB.bin&lt;/li&gt;
4498&lt;li&gt;100MB.bin&lt;/li&gt;
4499&lt;/ul&gt;
4500&lt;p&gt;After this we create FASTA files for all the binary files by encoding them
4501into DNA sequence.&lt;/p&gt;
4502&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;./dnae-encode -i 100MB.bin -o 100MB.fa
4503&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Then we GZIP all the FASTA files to see how much the can be compressed.&lt;/p&gt;
4504&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;gzip -9 &amp;lt; 10MB.fa &amp;gt; 10MB.fa.gz
4505&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;figure&gt;
4506&lt;img src=&#34;/posts/dna-sequence/chart-speed.svg&#34; alt=&#34;Encode to FASTA&#34; /&gt;
4507&lt;figcaption&gt;&lt;p&gt;The speed increase that occurs when encoding to FASTA format.&lt;/p&gt;&lt;/figcaption&gt;
4508&lt;/figure&gt;
4509&lt;figure&gt;
4510&lt;img src=&#34;/posts/dna-sequence/chart-size.svg&#34; alt=&#34;File sizes&#34; /&gt;
4511&lt;figcaption&gt;&lt;p&gt;Size of the out file after encoding.&lt;/p&gt;&lt;/figcaption&gt;
4512&lt;/figure&gt;
4513&lt;p&gt;&lt;a href=&#34;/posts/dna-sequence/benchmarks.csv&#34;&gt;Download CSV file with benchmarks&lt;/a&gt;.&lt;/p&gt;
4514&lt;h2 id=&#34;references&#34;&gt;References&lt;/h2&gt;
4515&lt;ul&gt;
4516&lt;li&gt;&lt;a href=&#34;https://www.techopedia.com/definition/948/encoding&#34;&gt;https://www.techopedia.com/definition/948/encoding&lt;/a&gt;&lt;/li&gt;
4517&lt;li&gt;&lt;a href=&#34;https://www.dna-worldwide.com/resource/160/history-dna-timeline&#34;&gt;https://www.dna-worldwide.com/resource/160/history-dna-timeline&lt;/a&gt;&lt;/li&gt;
4518&lt;li&gt;&lt;a href=&#34;https://opentextbc.ca/biology/chapter/9-1-the-structure-of-dna/&#34;&gt;https://opentextbc.ca/biology/chapter/9-1-the-structure-of-dna/&lt;/a&gt;&lt;/li&gt;
4519&lt;li&gt;&lt;a href=&#34;https://arxiv.org/abs/1801.04774&#34;&gt;https://arxiv.org/abs/1801.04774&lt;/a&gt;&lt;/li&gt;
4520&lt;li&gt;&lt;a href=&#34;https://en.wikipedia.org/wiki/FASTA_format&#34;&gt;https://en.wikipedia.org/wiki/FASTA_format&lt;/a&gt;&lt;/li&gt;
4521&lt;/ul&gt;
4522</content:encoded>
4523 </item>
4524
4525
4526
4527 <item>
4528 <title>Using DigitalOcean Spaces Object Storage with FUSE</title>
4529 <link>https://mitjafelicijan.com/using-digitalocean-spaces-object-storage-with-fuse.html</link>
4530 <pubDate>Tue, 16 Jan 2018 12:00:00 &#43;0200</pubDate>
4531 <guid>https://mitjafelicijan.com/using-digitalocean-spaces-object-storage-with-fuse.html</guid>
4532 <description>Couple of months ago DigitalOcean introduced newproduct calledSpaces whichis Object Storage very similar to Amazon&amp;#39;s S3.</description>
4533 <content:encoded>&lt;p&gt;Couple of months ago &lt;a href=&#34;https://www.digitalocean.com&#34;&gt;DigitalOcean&lt;/a&gt; introduced new
4534product called
4535&lt;a href=&#34;https://blog.digitalocean.com/introducing-spaces-object-storage/&#34;&gt;Spaces&lt;/a&gt; which
4536is Object Storage very similar to Amazon&#39;s S3. This really peaked my interest,
4537because this was something I was missing and even the thought of going over the
4538internet for such functionality was in no interest to me. Also in fashion with
4539their previous pricing this also is very cheap and pricing page is a no-brainer
4540compared to AWS or GCE. &lt;a href=&#34;https://www.digitalocean.com/pricing/&#34;&gt;Prices are clearly and precisely defined and
4541outlined&lt;/a&gt;. You must love them for that
4542:)&lt;/p&gt;
4543&lt;h2 id=&#34;initial-requirements&#34;&gt;Initial requirements&lt;/h2&gt;
4544&lt;ul&gt;
4545&lt;li&gt;Is it possible to use them as a mounted drive with FUSE? (tl;dr YES)&lt;/li&gt;
4546&lt;li&gt;Will the performance degrade over time and over different sizes of objects?
4547(tl;dr NO&amp;amp;YES)&lt;/li&gt;
4548&lt;li&gt;Can storage be mounted on multiple machines at the same time and be writable?
4549(tl;dr YES)&lt;/li&gt;
4550&lt;/ul&gt;
4551&lt;blockquote&gt;
4552&lt;p&gt;Let me be clear. This scripts I use are made just for benchmarking and are not
4553intended to be used in real-life situations. Besides that, I am looking into
4554using this approaches but adding caching service in front of it and then
4555dumping everything as an object to storage. This could potentially be some
4556interesting post of itself. But in case you would need real-time data without
4557eventual consistency please take this scripts as they are: not usable in such
4558situations.&lt;/p&gt;
4559&lt;/blockquote&gt;
4560&lt;h2 id=&#34;is-it-possible-to-use-them-as-a-mounted-drive-with-fuse&#34;&gt;Is it possible to use them as a mounted drive with FUSE?&lt;/h2&gt;
4561&lt;p&gt;Well, actually they can be used in such manor. Because they are similar to &lt;a href=&#34;https://aws.amazon.com/s3/&#34;&gt;AWS
4562S3&lt;/a&gt; many tools are available and you can find many
4563articles and &lt;a href=&#34;https://stackoverflow.com/search?q=s3&#43;fuse&#34;&gt;Stackoverflow items&lt;/a&gt;.&lt;/p&gt;
4564&lt;p&gt;To make this work you will need DigitalOcean account. If you don&#39;t have one you
4565will not be able to test this code. But if you have an account then you go and
4566&lt;a href=&#34;https://cloud.digitalocean.com/droplets/new?size=s-1vcpu-1gb&amp;amp;region=ams3&amp;amp;distro=debian&amp;amp;distroImage=debian-9-x64&amp;amp;options=private_networking,install_agent&#34;&gt;create new
4567Droplet&lt;/a&gt;.
4568If you click on this link you will already have preselected Debian 9 with
4569smallest VM option.&lt;/p&gt;
4570&lt;ul&gt;
4571&lt;li&gt;Please be sure to add you SSH key, because we will login to this machine
4572remotely.&lt;/li&gt;
4573&lt;li&gt;If you change your region please remember which one you choose because we will
4574need this information when we try to mount space to our machine.&lt;/li&gt;
4575&lt;/ul&gt;
4576&lt;p&gt;Instuctions on how to use SSH keys and how to setup them are available in
4577article &lt;a href=&#34;https://www.digitalocean.com/community/tutorials/how-to-use-ssh-keys-with-digitalocean-droplets&#34;&gt;How To Use SSH Keys with DigitalOcean
4578Droplets&lt;/a&gt;.&lt;/p&gt;
4579&lt;figure&gt;
4580&lt;img src=&#34;/posts/do-fuse/fuse-droplets.png&#34; alt=&#34;DigitalOcean Droplets&#34; /&gt;
4581&lt;/figure&gt;
4582&lt;p&gt;After we created Droplet it&#39;s time to create new Space. This is done by clicking
4583on a button &lt;a href=&#34;https://cloud.digitalocean.com/spaces/new&#34;&gt;Create&lt;/a&gt; (right top
4584corner) and selecting Spaces. Choose pronounceable &lt;code&gt;Unique name&lt;/code&gt; because we
4585will use it in examples below. You can either choose Private or Public, it
4586doesn&#39;t matter in our case. And you can always change that in the future.&lt;/p&gt;
4587&lt;p&gt;When you have created new Space we should &lt;a href=&#34;https://cloud.digitalocean.com/settings/api/tokens&#34;&gt;generate Access
4588key&lt;/a&gt;. This link will guide
4589to the page when you can generate this key. After you create new one, please
4590save provided Key and Secret because Secret will not be shown again.&lt;/p&gt;
4591&lt;figure&gt;
4592&lt;img src=&#34;/posts/do-fuse/fuse-spaces.png&#34; alt=&#34;DigitalOcean Spaces&#34; /&gt;
4593&lt;/figure&gt;
4594&lt;p&gt;Now that we have new Space and Access key we should SSH into our machine.&lt;/p&gt;
4595&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# replace IP with the ip of your newly created droplet&lt;/span&gt;
4596&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;ssh root@IP
4597&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4598&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# this will install utilities for mounting storage objects as FUSE&lt;/span&gt;
4599&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;apt install s3fs
4600&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4601&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# we now need to provide credentials (access key we created earlier)&lt;/span&gt;
4602&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# replace KEY and SECRET with your own credentials but leave the colon between them&lt;/span&gt;
4603&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# we also need to set proper permissions&lt;/span&gt;
4604&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;echo &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;KEY:SECRET&amp;#34;&lt;/span&gt; &amp;gt; .passwd-s3fs
4605&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;chmod 600 .passwd-s3fs
4606&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4607&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# now we mount space to our machine&lt;/span&gt;
4608&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# replace UNIQUE-NAME with the name you choose earlier&lt;/span&gt;
4609&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# if you choose different region for your space be careful about -ourl option (ams3)&lt;/span&gt;
4610&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;s3fs UNIQUE-NAME /mnt/ -ourl=https://ams3.digitaloceanspaces.com -ouse_cache=/tmp
4611&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4612&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# now we try to create a file&lt;/span&gt;
4613&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# once you mount it may take a couple of seconds to retrieve data&lt;/span&gt;
4614&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;echo &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Hello cruel world&amp;#34;&lt;/span&gt; &amp;gt; /mnt/hello.txt
4615&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;After all this you can return to your browser and go to &lt;a href=&#34;https://cloud.digitalocean.com/spaces&#34;&gt;DigitalOcean
4616Spaces&lt;/a&gt; and click on your created
4617space. If file hello.txt is present you have successfully mounted space to your
4618machine and wrote data to it.&lt;/p&gt;
4619&lt;p&gt;I choose the same region for my Droplet and my Space but you don&#39;t have to. You
4620can have different regions. What this actually does to performance I don&#39;t know.&lt;/p&gt;
4621&lt;p&gt;Additional information on FUSE:&lt;/p&gt;
4622&lt;ul&gt;
4623&lt;li&gt;&lt;a href=&#34;https://github.com/s3fs-fuse/s3fs-fuse&#34;&gt;Github project page for s3fs&lt;/a&gt;&lt;/li&gt;
4624&lt;li&gt;&lt;a href=&#34;https://en.wikipedia.org/wiki/Filesystem_in_Userspace&#34;&gt;FUSE - Filesystem in Userspace&lt;/a&gt;&lt;/li&gt;
4625&lt;/ul&gt;
4626&lt;h2 id=&#34;will-the-performance-degrade-over-time-and-over-different-sizes-of-objects&#34;&gt;Will the performance degrade over time and over different sizes of objects?&lt;/h2&gt;
4627&lt;p&gt;For this task I didn&#39;t want to just read and write text files or uploading
4628images. I actually wanted to figure out if using something like SQlite is viable
4629in this case.&lt;/p&gt;
4630&lt;h3 id=&#34;measurement-experiment-1-file-copy&#34;&gt;Measurement experiment 1: File copy&lt;/h3&gt;
4631&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# first we create some dummy files at different sizes&lt;/span&gt;
4632&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;dd &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt;=/dev/zero of=10KB.dat bs=1024 count=10 &lt;span style=&#34;color:#008000&#34;&gt;#10KB&lt;/span&gt;
4633&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;dd &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt;=/dev/zero of=100KB.dat bs=1024 count=100 &lt;span style=&#34;color:#008000&#34;&gt;#100KB&lt;/span&gt;
4634&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;dd &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt;=/dev/zero of=1MB.dat bs=1024 count=1024 &lt;span style=&#34;color:#008000&#34;&gt;#1MB&lt;/span&gt;
4635&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;dd &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt;=/dev/zero of=10MB.dat bs=1024 count=10240 &lt;span style=&#34;color:#008000&#34;&gt;#10MB&lt;/span&gt;
4636&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4637&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# now we set time command to only return real&lt;/span&gt;
4638&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;TIMEFORMAT=%R
4639&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4640&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# now lets test it&lt;/span&gt;
4641&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;(time cp 10KB.dat /mnt/) |&amp;amp; tee -a 10KB.results.txt
4642&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4643&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# and now we automate&lt;/span&gt;
4644&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# this will perform the same operation 100 times&lt;/span&gt;
4645&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# this will output results into separated files based on objecty size&lt;/span&gt;
4646&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;n=0; &lt;span style=&#34;color:#00f&#34;&gt;while&lt;/span&gt; (( n&#43;&#43; &amp;lt; 100 )); &lt;span style=&#34;color:#00f&#34;&gt;do&lt;/span&gt; (time cp 10KB.dat /mnt/10KB.$n.dat) |&amp;amp; tee -a 10KB.results.txt; &lt;span style=&#34;color:#00f&#34;&gt;done&lt;/span&gt;
4647&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;n=0; &lt;span style=&#34;color:#00f&#34;&gt;while&lt;/span&gt; (( n&#43;&#43; &amp;lt; 100 )); &lt;span style=&#34;color:#00f&#34;&gt;do&lt;/span&gt; (time cp 100KB.dat /mnt/100KB.$n.dat) |&amp;amp; tee -a 100KB.results.txt; &lt;span style=&#34;color:#00f&#34;&gt;done&lt;/span&gt;
4648&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;n=0; &lt;span style=&#34;color:#00f&#34;&gt;while&lt;/span&gt; (( n&#43;&#43; &amp;lt; 100 )); &lt;span style=&#34;color:#00f&#34;&gt;do&lt;/span&gt; (time cp 1MB.dat /mnt/1MB.$n.dat) |&amp;amp; tee -a 1MB.results.txt; &lt;span style=&#34;color:#00f&#34;&gt;done&lt;/span&gt;
4649&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;n=0; &lt;span style=&#34;color:#00f&#34;&gt;while&lt;/span&gt; (( n&#43;&#43; &amp;lt; 100 )); &lt;span style=&#34;color:#00f&#34;&gt;do&lt;/span&gt; (time cp 10MB.dat /mnt/10MB.$n.dat) |&amp;amp; tee -a 10MB.results.txt; &lt;span style=&#34;color:#00f&#34;&gt;done&lt;/span&gt;
4650&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Files of size 100MB were not successfully transferred and ended up displaying
4651error (cp: failed to close &#39;/mnt/100MB.1.dat&#39;: Operation not permitted).&lt;/p&gt;
4652&lt;p&gt;As I suspected, object size is not really that important. Sadly I don&#39;t have the
4653time to test performance over periods of time. But if some of you would do it
4654please send me your data. I would be interested in seeing results.&lt;/p&gt;
4655&lt;p&gt;&lt;strong&gt;Here are plotted results&lt;/strong&gt;&lt;/p&gt;
4656&lt;p&gt;You can download &lt;a href=&#34;/posts/do-fuse/copy-benchmarks.tsv&#34;&gt;raw result here&lt;/a&gt;.
4657Measurements are in seconds.&lt;/p&gt;
4658&lt;script src=&#34;//cdn.plot.ly/plotly-latest.min.js&#34;&gt;&lt;/script&gt;
4659&lt;div id=&#34;copy-benchmarks&#34;&gt;&lt;/div&gt;
4660&lt;script&gt;
4661(function(){
4662 var request = new XMLHttpRequest();
4663 request.open(&#34;GET&#34;, &#34;/posts/do-fuse/copy-benchmarks.tsv&#34;, true);
4664 request.onload = function() {
4665 if (request.status &gt;= 200 &amp;&amp; request.status &lt; 400) {
4666 var payload = request.responseText.trim();
4667 var tsv = payload.split(&#34;\n&#34;);
4668 for (var i=0; i&lt;tsv.length; i&#43;&#43;) { tsv[i] = tsv[i].split(&#34;\t&#34;); }
4669 var traces = [];
4670 var headers = tsv[0];
4671 tsv.shift();
4672 Array.prototype.forEach.call(headers, function(el, idx) {
4673 var x = [];
4674 var y = [];
4675 for (var j=0; j&lt;tsv.length; j&#43;&#43;) {
4676 x.push(j);
4677 y.push(parseFloat(tsv[j][idx].replace(&#34;,&#34;, &#34;.&#34;)));
4678 }
4679 traces.push({ x: x, y: y, type: &#34;scatter&#34;, name: el, line: { width: 1, shape: &#34;spline&#34; } });
4680 });
4681 var copy = Plotly.newPlot(&#34;copy-benchmarks&#34;, traces, { legend: {&#34;orientation&#34;: &#34;h&#34;}, height: 400, margin: { l: 40, r: 0, b: 20, t: 30, pad: 0 }, yaxis: { title: &#34;execution time in seconds&#34;, titlefont: { size: 12 } }, xaxis: { title: &#34;fn(i)&#34;, titlefont: { size: 12 } } });
4682 } else { }
4683 };
4684 request.onerror = function() { };
4685 request.send(null);
4686})();
4687&lt;/script&gt;
4688&lt;p&gt;As far as these tests show, performance is quite stable and can be predicted
4689which is fantastic. But this is a small test and spans only over couple of
4690hours. So you should not completely trust them.&lt;/p&gt;
4691&lt;h3 id=&#34;measurement-experiment-2-sqlite-performanse&#34;&gt;Measurement experiment 2: SQLite performanse&lt;/h3&gt;
4692&lt;p&gt;I was unable to use database file directly from mounted drive so this is a no-go
4693as I suspected. So I executed code below on a local disk just to get some
4694benchmarks. I inserted 1000 records with DROPTABLE, CREATETABLE, INSERTMANY,
4695FETCHALL, COMMIT for 1000 times to generate statistics. As you can see
4696performance of SQLite is quite amazing. You could then potentially just copy
4697file to mounted drive and be done with it.&lt;/p&gt;
4698&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; time
4699&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; sqlite3
4700&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; sys
4701&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4702&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; len(sys.argv) &amp;lt; 3:
4703&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;usage: python sqlite-benchmark.py DB_PATH NUM_RECORDS REPEAT&amp;#34;&lt;/span&gt;)
4704&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; exit()
4705&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4706&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;def&lt;/span&gt; data_iter(x):
4707&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; i &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; range(x):
4708&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;yield&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;m&amp;#34;&lt;/span&gt; &#43; str(i), &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;f&amp;#34;&lt;/span&gt; &#43; str(i*i)
4709&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4710&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;header_line = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%s&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\t&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%s&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\t&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%s&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\t&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%s&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\t&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%s&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\n&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt; % (&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;DROPTABLE&amp;#34;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;CREATETABLE&amp;#34;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;INSERTMANY&amp;#34;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;FETCHALL&amp;#34;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;COMMIT&amp;#34;&lt;/span&gt;)
4711&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;with&lt;/span&gt; open(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;sqlite-benchmarks.tsv&amp;#34;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;w&amp;#34;&lt;/span&gt;) &lt;span style=&#34;color:#00f&#34;&gt;as&lt;/span&gt; fp:
4712&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; fp.write(header_line)
4713&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4714&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;start_time = time.time()
4715&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;conn = sqlite3.connect(sys.argv[1])
4716&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;c = conn.cursor()
4717&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;end_time = time.time()
4718&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;result_time = CONNECT = end_time - start_time
4719&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;CONNECT: &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%g&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; seconds&amp;#34;&lt;/span&gt; % (result_time))
4720&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4721&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;start_time = time.time()
4722&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;c.execute(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;PRAGMA journal_mode=WAL&amp;#34;&lt;/span&gt;)
4723&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;c.execute(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;PRAGMA temp_store=MEMORY&amp;#34;&lt;/span&gt;)
4724&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;c.execute(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;PRAGMA synchronous=OFF&amp;#34;&lt;/span&gt;)
4725&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;result_time = PRAGMA = end_time - start_time
4726&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;PRAGMA: &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%g&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; seconds&amp;#34;&lt;/span&gt; % (result_time))
4727&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4728&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; i &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; range(int(sys.argv[3])):
4729&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;#&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%i&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt; % (i))
4730&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4731&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; start_time = time.time()
4732&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; c.execute(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;drop table if exists test&amp;#34;&lt;/span&gt;)
4733&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; end_time = time.time()
4734&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; result_time = DROPTABLE = end_time - start_time
4735&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;DROPTABLE: &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%g&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; seconds&amp;#34;&lt;/span&gt; % (result_time))
4736&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4737&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; start_time = time.time()
4738&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; c.execute(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;create table if not exists test(a,b)&amp;#34;&lt;/span&gt;)
4739&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; end_time = time.time()
4740&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; result_time = CREATETABLE = end_time - start_time
4741&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;CREATETABLE: &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%g&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; seconds&amp;#34;&lt;/span&gt; % (result_time))
4742&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4743&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; start_time = time.time()
4744&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; c.executemany(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;INSERT INTO test VALUES (?, ?)&amp;#34;&lt;/span&gt;, data_iter(int(sys.argv[2])))
4745&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; end_time = time.time()
4746&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; result_time = INSERTMANY = end_time - start_time
4747&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;INSERTMANY: &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%g&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; seconds&amp;#34;&lt;/span&gt; % (result_time))
4748&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4749&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; start_time = time.time()
4750&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; c.execute(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;select count(*) from test&amp;#34;&lt;/span&gt;)
4751&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; res = c.fetchall()
4752&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; end_time = time.time()
4753&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; result_time = FETCHALL = end_time - start_time
4754&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;FETCHALL: &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%g&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; seconds&amp;#34;&lt;/span&gt; % (result_time))
4755&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4756&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; start_time = time.time()
4757&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; conn.commit()
4758&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; end_time = time.time()
4759&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; result_time = COMMIT = end_time - start_time
4760&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;COMMIT: &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%g&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; seconds&amp;#34;&lt;/span&gt; % (result_time))
4761&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4762&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; print
4763&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; log_line = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%f&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\t&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%f&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\t&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%f&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\t&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%f&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\t&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%f&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;\n&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt; % (DROPTABLE, CREATETABLE, INSERTMANY, FETCHALL, COMMIT)
4764&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;with&lt;/span&gt; open(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;sqlite-benchmarks.tsv&amp;#34;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;a&amp;#34;&lt;/span&gt;) &lt;span style=&#34;color:#00f&#34;&gt;as&lt;/span&gt; fp:
4765&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; fp.write(log_line)
4766&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4767&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;start_time = time.time()
4768&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;conn.close()
4769&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;end_time = time.time()
4770&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;result_time = CLOSE = end_time - start_time
4771&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;CLOSE: &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%g&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; seconds&amp;#34;&lt;/span&gt; % (result_time))
4772&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;You can download &lt;a href=&#34;/posts/do-fuse/sqlite-benchmarks.tsv&#34;&gt;raw result here&lt;/a&gt;. And
4773again, these results are done on a local block storage and do not represent
4774capabilities of object storage. With my current approach and state of the test
4775code these can not be done. I would need to make Python code much more robust
4776and check locking etc.&lt;/p&gt;
4777&lt;div id=&#34;sqlite-benchmarks&#34;&gt;&lt;/div&gt;
4778&lt;script&gt;
4779(function(){
4780 var request = new XMLHttpRequest();
4781 request.open(&#34;GET&#34;, &#34;/posts/do-fuse/sqlite-benchmarks.tsv&#34;, true);
4782 request.onload = function() {
4783 if (request.status &gt;= 200 &amp;&amp; request.status &lt; 400) {
4784 var payload = request.responseText.trim();
4785 var tsv = payload.split(&#34;\n&#34;);
4786 for (var i=0; i&lt;tsv.length; i&#43;&#43;) { tsv[i] = tsv[i].split(&#34;\t&#34;); }
4787 var traces = [];
4788 var headers = tsv[0];
4789 tsv.shift();
4790 Array.prototype.forEach.call(headers, function(el, idx) {
4791 var x = [];
4792 var y = [];
4793 for (var j=0; j&lt;tsv.length; j&#43;&#43;) {
4794 x.push(j);
4795 y.push(parseFloat(tsv[j][idx].replace(&#34;,&#34;, &#34;.&#34;)));
4796 }
4797 traces.push({ x: x, y: y, type: &#34;scatter&#34;, name: el, line: { width: 1, shape: &#34;spline&#34; } });
4798 });
4799 var sqlite = Plotly.newPlot(&#34;sqlite-benchmarks&#34;, traces, { legend: {&#34;orientation&#34;: &#34;h&#34;}, height: 400, margin: { l: 50, r: 0, b: 20, t: 30, pad: 0 }, yaxis: { title: &#34;execution time in seconds&#34;, titlefont: { size: 12 } } });
4800 } else { }
4801 };
4802 request.onerror = function() { };
4803 request.send(null);
4804})();
4805&lt;/script&gt;
4806&lt;h2 id=&#34;can-storage-be-mounted-on-multiple-machines-at-the-same-time-and-be-writable&#34;&gt;Can storage be mounted on multiple machines at the same time and be writable?&lt;/h2&gt;
4807&lt;p&gt;Well, this one didn&#39;t take long to test. And the answer is &lt;strong&gt;YES&lt;/strong&gt;. I mounted
4808space on both machines and measured same performance on both machines. But
4809because file is downloaded before write and then uploaded on complete there
4810could potentially be problems is another process is trying to access the same
4811file.&lt;/p&gt;
4812&lt;h2 id=&#34;observations-and-conslusion&#34;&gt;Observations and conslusion&lt;/h2&gt;
4813&lt;p&gt;Using Spaces in this way makes it easier to access and manage files. But besides
4814that you would need to write additional code to make this one play nice with you
4815applications.&lt;/p&gt;
4816&lt;p&gt;Nevertheless, this was extremely simple to setup and use and this is just
4817another excellent product in DigitalOcean product line. I found this exercise
4818very valuable and am thinking about implementing some sort of mechanism for
4819SQLite, so data can be stored on Spaces and accessed by many VM&#39;s. For a project
4820where data doesn&#39;t need to be accessible in real-time and can have couple of
4821minutes old data this would be very interesting. If any of you find this
4822proposal interesting please write in a comment box below or shoot me an email
4823and I will keep you posted.&lt;/p&gt;
4824</content:encoded>
4825 </item>
4826
4827
4828
4829 <item>
4830 <title>Simple IOT application supported by real-time monitoring and data history</title>
4831 <link>https://mitjafelicijan.com/simple-iot-application.html</link>
4832 <pubDate>Fri, 11 Aug 2017 12:00:00 &#43;0200</pubDate>
4833 <guid>https://mitjafelicijan.com/simple-iot-application.html</guid>
4834 <description>Initial thoughtsI have been developing these kind of application for the better part of my last5 years and people keep asking me how to approach developing such applicationand I will give a try explaining it here.</description>
4835 <content:encoded>&lt;h2 id=&#34;initial-thoughts&#34;&gt;Initial thoughts&lt;/h2&gt;
4836&lt;p&gt;I have been developing these kind of application for the better part of my last
48375 years and people keep asking me how to approach developing such application
4838and I will give a try explaining it here.&lt;/p&gt;
4839&lt;p&gt;IOT applications are really no different than any other kind of applications.
4840We have data that needs to be collected and visualized in some form of tables or
4841charts. The main difference here is that most of the times these data is
4842collected by some kind of device foreign to developer that mainly operates in
4843web domain. But fear not, it&#39;s not that different than writing some JavaScript.&lt;/p&gt;
4844&lt;p&gt;There are many devices able to transmit data via wireless or wired network by
4845default but for the sake of example we will be using commonly known Arduino with
4846wireless module already on the board → &lt;a href=&#34;https://store.arduino.cc/arduino-mkr1000&#34;&gt;Arduino
4847MKR1000&lt;/a&gt;.&lt;/p&gt;
4848&lt;p&gt;In order to make this little project as accessible to others as possible I will
4849try to make it as inexpensive as possible. And by this I mean that I will avoid
4850using hosted virtual servers and will be using my own laptop as a server. But
4851you must buy Arduino MKR1000 to follow steps below. But if you would want to
4852deploy this software I would suggest using
4853&lt;a href=&#34;https://www.digitalocean.com&#34;&gt;DigitalOcean&lt;/a&gt; → smallest VPS is only per month
4854making this one of the most affordable option out there. Please notice that this
4855software will not run on stock web hosting that only supports LAMP (Linux,
4856Apache, MySQL, and PHP).&lt;/p&gt;
4857&lt;p&gt;But before we begin please take notice that this is strictly experimental code
4858and not well optimized and there are much better ways in handling some aspects
4859of the application but that requires much deeper knowledge of technology that is
4860not needed for an example like this.&lt;/p&gt;
4861&lt;p&gt;&lt;strong&gt;Development steps&lt;/strong&gt;&lt;/p&gt;
4862&lt;ol&gt;
4863&lt;li&gt;Simple Python API that will receive and store incoming data.&lt;/li&gt;
4864&lt;li&gt;Prototype C&#43;&#43; code that will read &amp;quot;sensor data&amp;quot; and transmit it to API.&lt;/li&gt;
4865&lt;li&gt;Data visualization with charts → extends Python web application.&lt;/li&gt;
4866&lt;/ol&gt;
4867&lt;p&gt;Step 1. and 3. will share the same web application. One route will be dedicated
4868to API and another to serving HTML with chart.&lt;/p&gt;
4869&lt;p&gt;Schema below represents what we will try to achieve and how different parts
4870correlates to each other.&lt;/p&gt;
4871&lt;figure&gt;
4872&lt;img src=&#34;/posts/iot-application/simple-iot-application-overview.svg&#34; alt=&#34;Overview&#34; /&gt;
4873&lt;/figure&gt;
4874&lt;h2 id=&#34;simple-python-api&#34;&gt;Simple Python API&lt;/h2&gt;
4875&lt;p&gt;I have always been a fan of simplicity so we will be using &lt;a href=&#34;https://bottlepy.org/docs/dev/&#34;&gt;Bottle: Python Web
4876Framework&lt;/a&gt;. It is a single file web framework
4877that seriously simplifies working with routes, templating and has built-in web
4878server that satisfies our need in this case.&lt;/p&gt;
4879&lt;p&gt;First we need to install bottle package. This can be done by downloading
4880&lt;code&gt;bottle.py&lt;/code&gt; and placing it in the root of your application or by using pip
4881software &lt;code&gt;pip install bottle --user&lt;/code&gt;.&lt;/p&gt;
4882&lt;p&gt;If you are using Linux or MacOS then Python is already installed. If you will
4883try to test this on Windows please install &lt;a href=&#34;https://www.python.org/downloads/windows/&#34;&gt;Python for
4884Windows&lt;/a&gt;. There may be some problems
4885with path when you will try to launch &lt;code&gt;python webapp.py&lt;/code&gt; so please take care
4886of this before you continue.&lt;/p&gt;
4887&lt;h3 id=&#34;basic-web-application&#34;&gt;Basic web application&lt;/h3&gt;
4888&lt;p&gt;Most basic bottle application is quite simple. Paste code below in
4889&lt;code&gt;webapp.py&lt;/code&gt; file and save.&lt;/p&gt;
4890&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# -*- coding: utf-8 -*-&lt;/span&gt;
4891&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4892&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; bottle
4893&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4894&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# initializing bottle app&lt;/span&gt;
4895&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;app = bottle.Bottle()
4896&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4897&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# triggered when / is accessed from browser&lt;/span&gt;
4898&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# only accepts GET → no POST allowed&lt;/span&gt;
4899&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@app.route(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;/&amp;#34;&lt;/span&gt;, method=[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;GET&amp;#34;&lt;/span&gt;])
4900&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;def&lt;/span&gt; route_default():
4901&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;howdy from python&amp;#34;&lt;/span&gt;
4902&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4903&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# starting server on http://0.0.0.0:5000&lt;/span&gt;
4904&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; __name__ == &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;__main__&amp;#34;&lt;/span&gt;:
4905&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; bottle.run(
4906&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; app = app,
4907&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; host = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;0.0.0.0&amp;#34;&lt;/span&gt;,
4908&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; port = 5000,
4909&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; debug = &lt;span style=&#34;color:#00f&#34;&gt;True&lt;/span&gt;,
4910&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; reloader = &lt;span style=&#34;color:#00f&#34;&gt;True&lt;/span&gt;,
4911&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; catchall = &lt;span style=&#34;color:#00f&#34;&gt;True&lt;/span&gt;,
4912&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; )
4913&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;To run this simple application you should open command prompt or terminal on
4914your machine and go to the folder containing your file and type &lt;code&gt;python webapp.py&lt;/code&gt;. If everything goes ok then open your web browser and point it to
4915&lt;code&gt;http://0.0.0.0:5000&lt;/code&gt;.&lt;/p&gt;
4916&lt;p&gt;If you would like change the port of your application (like port 80) and not use
4917root to run your app this will present a problem. The TCP/IP port numbers below
49181024 are privileged ports → this is a security feature. So in order of
4919simplicity and security use a port number above 1024 like I have used port 5000.&lt;/p&gt;
4920&lt;p&gt;If this fails at any time please fix it before you continue, because nothing
4921below will work otherwise.&lt;/p&gt;
4922&lt;p&gt;We use 0.0.0.0 as default host so that this app is available over your local
4923network. If you find your local ip &lt;code&gt;ifconfig&lt;/code&gt; and try accessing this site
4924with your phone (if on same network/router as your machine) this should work as
4925well (example of such ip &lt;code&gt;http://192.168.1.15:5000&lt;/code&gt;). This is a must have
4926because Arduino will be accessing this application to send it&#39;s data.&lt;/p&gt;
4927&lt;h3 id=&#34;web-application-security&#34;&gt;Web application security&lt;/h3&gt;
4928&lt;p&gt;There is a lot to be said about security and is a topic of many books. Of course
4929all this can not be written here but to just establish some basic security → you
4930should always use SSL with your application. Some fantastic free certificates
4931are available by &lt;a href=&#34;https://letsencrypt.org&#34;&gt;Let&#39;s Encrypt - Free SSL/TLS
4932Certificates&lt;/a&gt;. With SSL certificate installed you
4933should then make use of HTTP headers and send your &amp;quot;API key&amp;quot; via a header. If
4934your key is send via header then this key is encrypted by SSL and send encrypted
4935over the network. Never send your api keys by GET parameter like
4936&lt;code&gt;http://example.com/?api_key=somekeyvalue&lt;/code&gt;. The problem that this kind of
4937sending presents is that this key is visible in logs and by network sniffers.&lt;/p&gt;
4938&lt;p&gt;There is a fantastic article describing some aspects about security: &lt;a href=&#34;https://www.keycdn.com/blog/web-application-security-best-practices/&#34;&gt;11 Web
4939Application Security Best
4940Practices&lt;/a&gt;. Please
4941check it out.&lt;/p&gt;
4942&lt;h3 id=&#34;simple-api-for-writing-data-points&#34;&gt;Simple API for writing data-points&lt;/h3&gt;
4943&lt;p&gt;We will now be using boilerplate code from example above and extend it to be
4944SQLite3 because it plays well with Python and can store quite large amount of
4945able to write data received by API to local storage. For example use I will use
4946data. I have been using it to collect gigabytes of data in a single database
4947without any corruption or problems → your experience may vary.&lt;/p&gt;
4948&lt;p&gt;To avoid learning SQLite I will be using &lt;a href=&#34;https://dataset.readthedocs.io/en/latest/index.html&#34;&gt;Dataset: databases for lazy
4949people&lt;/a&gt;. This package
4950abstracts SQL and simplifies writing and reading data from database. You should
4951install this package with pip software &lt;code&gt;pip install dataset --user&lt;/code&gt;.&lt;/p&gt;
4952&lt;p&gt;Because API will use POST method I will be testing if code works correctly by
4953using &lt;a href=&#34;https://chrome.google.com/webstore/detail/restlet-client-rest-api-t/aejoelaoggembcahagimdiliamlcdmfm&#34;&gt;Restlet Client for Google
4954Chrome&lt;/a&gt;.
4955This software also allows you to set headers → for basic security with API_KEY.&lt;/p&gt;
4956&lt;p&gt;To quickly generate passwords or API keys I usually use this nifty website
4957&lt;a href=&#34;https://randomkeygen.com/&#34;&gt;RandomKeygen&lt;/a&gt;.&lt;/p&gt;
4958&lt;p&gt;Copy and paste code below over your previous code in file &lt;code&gt;webapp.py&lt;/code&gt;.&lt;/p&gt;
4959&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# -*- coding: utf-8 -*-&lt;/span&gt;
4960&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4961&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; time
4962&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; bottle
4963&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; random
4964&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; dataset
4965&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4966&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# initializing bottle app&lt;/span&gt;
4967&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;app = bottle.Bottle()
4968&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4969&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# connects to sqlite database&lt;/span&gt;
4970&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# check_same_thread=False allows using it in multi-threaded mode&lt;/span&gt;
4971&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;app.config[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;dsn&amp;#34;&lt;/span&gt;] = dataset.connect(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;sqlite:///data.db?check_same_thread=False&amp;#34;&lt;/span&gt;)
4972&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4973&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# api key that will be used in Arduino code&lt;/span&gt;
4974&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;app.config[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;api_key&amp;#34;&lt;/span&gt;] = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;JtF2aUE5SGHfVJBCG5SH&amp;#34;&lt;/span&gt;
4975&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4976&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# triggered when /api is accessed from browser&lt;/span&gt;
4977&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# only accepts POST → no GET allowed&lt;/span&gt;
4978&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@app.route(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;/api&amp;#34;&lt;/span&gt;, method=[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;POST&amp;#34;&lt;/span&gt;])
4979&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;def&lt;/span&gt; route_default():
4980&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; status = 400
4981&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; ts = int(time.time()) &lt;span style=&#34;color:#008000&#34;&gt;# current timestamp&lt;/span&gt;
4982&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; value = bottle.request.body.read() &lt;span style=&#34;color:#008000&#34;&gt;# data from device&lt;/span&gt;
4983&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; api_key = bottle.request.get_header(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Api_Key&amp;#34;&lt;/span&gt;) &lt;span style=&#34;color:#008000&#34;&gt;# api key from header&lt;/span&gt;
4984&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4985&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;# outputs to console received data for debug reason&lt;/span&gt;
4986&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; print &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&amp;gt;&amp;gt;&amp;gt; &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;{}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; :: &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;{}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt;.format(value, api_key)
4987&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4988&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;# if api_key is correct and value is present&lt;/span&gt;
4989&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;# then writes attribute to point table&lt;/span&gt;
4990&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; api_key == app.config[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;api_key&amp;#34;&lt;/span&gt;] &lt;span style=&#34;color:#00f&#34;&gt;and&lt;/span&gt; value:
4991&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; app.config[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;dsn&amp;#34;&lt;/span&gt;][&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;point&amp;#34;&lt;/span&gt;].insert(dict(ts=ts, value=value))
4992&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; status = 200
4993&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4994&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;# we only need to return status&lt;/span&gt;
4995&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt; bottle.HTTPResponse(status=status, body=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&amp;#34;&lt;/span&gt;)
4996&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
4997&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# starting server on http://0.0.0.0:5000&lt;/span&gt;
4998&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; __name__ == &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;__main__&amp;#34;&lt;/span&gt;:
4999&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; bottle.run(
5000&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; app = app,
5001&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; host = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;0.0.0.0&amp;#34;&lt;/span&gt;,
5002&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; port = 5000,
5003&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; debug = &lt;span style=&#34;color:#00f&#34;&gt;True&lt;/span&gt;,
5004&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; reloader = &lt;span style=&#34;color:#00f&#34;&gt;True&lt;/span&gt;,
5005&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; catchall = &lt;span style=&#34;color:#00f&#34;&gt;True&lt;/span&gt;,
5006&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; )
5007&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;To run this simply go to folder containing python file and run &lt;code&gt;python webapp.py&lt;/code&gt; from terminal. If everything goes ok you should have simple API
5008available via POST method on /api route.&lt;/p&gt;
5009&lt;p&gt;After testing the service with Restlet Client you should be able to view your
5010data in a database file &lt;code&gt;data.db&lt;/code&gt;.&lt;/p&gt;
5011&lt;figure&gt;
5012&lt;img src=&#34;/posts/iot-application/iot-rest-example.png&#34; alt=&#34;REST settings example&#34; /&gt;
5013&lt;/figure&gt;
5014&lt;p&gt;You can also check the contents of new database file by using desktop client
5015for SQLite → &lt;a href=&#34;http://sqlitebrowser.org/&#34;&gt;DB Browser for SQLite&lt;/a&gt;.&lt;/p&gt;
5016&lt;figure&gt;
5017&lt;img src=&#34;/posts/iot-application/iot-sqlite-db.png&#34; alt=&#34;SQLite database example&#34; /&gt;
5018&lt;/figure&gt;
5019&lt;p&gt;Table structure is as simple as it can be. We have ts (timestamp) and value
5020(value from Arduino). As you can see timestamp is generated on API side. If you
5021would happen to have atomic clock on Arduino it would be then better to generate
5022and send timestamp with the value. This would be particularity useful if we
5023would be collecting sensor data at a higher frequency and then sending this data
5024in bulk to API.&lt;/p&gt;
5025&lt;p&gt;If you will deploy this app with uWSGI and multi-threaded, use DSN (Data Source
5026Name) url with &lt;code&gt;?check_same_thread=False&lt;/code&gt;.&lt;/p&gt;
5027&lt;p&gt;Ok, now that we have some sort of a working API with some basic security so
5028unwanted people can not post data to your database can we proceed further and
5029try to program Arduino to send data to API.&lt;/p&gt;
5030&lt;h2 id=&#34;sending-data-to-api-with-arduino-mkr1000&#34;&gt;Sending data to API with Arduino MKR1000&lt;/h2&gt;
5031&lt;p&gt;First of all you should have MKR1000 module and microUSB cable to proceed. If
5032you have ever done any work with Arduino you should know that you also need
5033&lt;a href=&#34;https://www.arduino.cc/en/Main/Software&#34;&gt;Arduino IDE&lt;/a&gt;. On provided link you
5034should be able to download and install IDE. Once that task is completed and you
5035have successfully run blink example you should proceed to the next step.&lt;/p&gt;
5036&lt;p&gt;In order to use wireless capabilities of MKR1000 you need to first install
5037&lt;a href=&#34;https://www.arduino.cc/en/Reference/WiFi101&#34;&gt;WiFi101 library&lt;/a&gt; in Arduino IDE.
5038Please check before you install, you may already have it installed.&lt;/p&gt;
5039&lt;p&gt;Code below is a working example that sends data to API. Before you try to test
5040your code make sure you have run Python web application. Then change settings
5041for wifi, api endpoint and api_key. If by some reason code bellow doesn&#39;t work
5042for you please leave a comment and I&#39;ll try to help.&lt;/p&gt;
5043&lt;p&gt;Once you have opened IDE and copied this code try to compile and upload it.
5044Then open &amp;quot;Serial monitor&amp;quot; to see if any output is presented by Arduino.&lt;/p&gt;
5045&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;#include&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;&amp;lt;WiFi101.h&amp;gt;&lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;
5046&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;&lt;/span&gt;
5047&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// wifi settings
5048&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;&lt;span style=&#34;color:#2b91af&#34;&gt;char&lt;/span&gt; ssid[] = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;ssid-name&amp;#34;&lt;/span&gt;;
5049&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#2b91af&#34;&gt;char&lt;/span&gt; pass[] = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;ssid-password&amp;#34;&lt;/span&gt;;
5050&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5051&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// api server enpoint
5052&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;&lt;span style=&#34;color:#2b91af&#34;&gt;char&lt;/span&gt; server[] = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;192.168.6.22&amp;#34;&lt;/span&gt;;
5053&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#2b91af&#34;&gt;int&lt;/span&gt; port = 5000;
5054&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5055&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// api key that must be the same as the one in Python code
5056&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;String api_key = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;JtF2aUE5SGHfVJBCG5SH&amp;#34;&lt;/span&gt;;
5057&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5058&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;// frequency data is sent in ms - every 5 seconds
5059&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;&lt;span style=&#34;color:#2b91af&#34;&gt;int&lt;/span&gt; timeout = 1000 * 5;
5060&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5061&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#2b91af&#34;&gt;int&lt;/span&gt; status = WL_IDLE_STATUS;
5062&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5063&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#2b91af&#34;&gt;void&lt;/span&gt; setup() {
5064&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5065&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// initialize serial and wait for port to open:
5066&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; Serial.begin(9600);
5067&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; delay(1000);
5068&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5069&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// check for the presence of the shield
5070&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; (WiFi.status() == WL_NO_SHIELD) {
5071&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Serial.println(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;WiFi shield not present&amp;#34;&lt;/span&gt;);
5072&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;while&lt;/span&gt; (true);
5073&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5074&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5075&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// attempt to connect to wifi network
5076&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;while&lt;/span&gt; (status != WL_CONNECTED) {
5077&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Serial.print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Attempting to connect to SSID: &amp;#34;&lt;/span&gt;);
5078&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Serial.println(ssid);
5079&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; status = WiFi.begin(ssid, pass);
5080&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// wait 10 seconds for connection
5081&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; delay(10000);
5082&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5083&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5084&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// output wifi status to serial monitor
5085&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; Serial.print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;SSID: &amp;#34;&lt;/span&gt;);
5086&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Serial.println(WiFi.SSID());
5087&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5088&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; IPAddress ip = WiFi.localIP();
5089&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Serial.print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;IP Address: &amp;#34;&lt;/span&gt;);
5090&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Serial.println(ip);
5091&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5092&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#2b91af&#34;&gt;long&lt;/span&gt; rssi = WiFi.RSSI();
5093&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Serial.print(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;signal strength (RSSI):&amp;#34;&lt;/span&gt;);
5094&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Serial.print(rssi);
5095&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Serial.println(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34; dBm&amp;#34;&lt;/span&gt;);
5096&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
5097&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5098&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#2b91af&#34;&gt;void&lt;/span&gt; loop() {
5099&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; WiFiClient client;
5100&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5101&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; (client.connect(server, port)) {
5102&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5103&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// I use random number generator for this example
5104&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// but you can use analog or digital inputs from arduino
5105&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; String content = String(random(1000));
5106&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5107&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; client.println(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;POST /api HTTP/1.1&amp;#34;&lt;/span&gt;);
5108&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; client.println(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Connection: close&amp;#34;&lt;/span&gt;);
5109&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; client.println(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Api-Key: &amp;#34;&lt;/span&gt; &#43; api_key);
5110&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; client.println(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Content-Length: &amp;#34;&lt;/span&gt; &#43; String(content.length()));
5111&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; client.println();
5112&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; client.println(content);
5113&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5114&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; delay(100);
5115&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; client.stop();
5116&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Serial.println(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Data sent successfully ...&amp;#34;&lt;/span&gt;);
5117&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5118&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; } &lt;span style=&#34;color:#00f&#34;&gt;else&lt;/span&gt; {
5119&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; Serial.println(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Problem sending data ...&amp;#34;&lt;/span&gt;);
5120&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5121&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5122&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// waits for x seconds and continue looping
5123&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; delay(timeout);
5124&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
5125&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;As seen from example you can notice that Arduino is generating random integer
5126between [ 0 .. 1000 ]. You can easily replace this with a temperature sensor or
5127any other kind of sensor.&lt;/p&gt;
5128&lt;p&gt;Now that we have API under the hood and Arduino is sending demo data we can now
5129focus on data visualization.&lt;/p&gt;
5130&lt;h2 id=&#34;data-visualization&#34;&gt;Data visualization&lt;/h2&gt;
5131&lt;p&gt;Before we continue we should examine our project folder structure. Currently we
5132only have two files in our project:&lt;/p&gt;
5133&lt;p&gt;&lt;em&gt;simple-iot-app/&lt;/em&gt;&lt;/p&gt;
5134&lt;ul&gt;
5135&lt;li&gt;&lt;em&gt;webapp.py&lt;/em&gt;&lt;/li&gt;
5136&lt;li&gt;&lt;em&gt;data.db&lt;/em&gt;&lt;/li&gt;
5137&lt;/ul&gt;
5138&lt;p&gt;We will now add HTML template that will contain CSS and JavaScript code inline
5139for the simplicity reason. And for the bottle framework to be able to scan root
5140application folder for templates we will add &lt;code&gt;bottle.TEMPLATE_PATH.insert(0, &amp;quot;./&amp;quot;)&lt;/code&gt; in &lt;code&gt;webapp.py&lt;/code&gt;. By default bottle framework uses &lt;code&gt;views/&lt;/code&gt;
5141subfolder to store templates. This is not the ideal situation and if you will
5142use bottle to develop web applications you should use native behavior and store
5143templates in it&#39;s predefined folder. But for the sake of example we will
5144over-ride this. Be careful to fully replace your code with new code that is
5145provided below. Avoid partially replacing code in file :) Also new code for
5146reading data-points is provided in Python example below.&lt;/p&gt;
5147&lt;p&gt;First we add new route to our web application. It should be trigger when browser
5148hits root of application &lt;code&gt;http://0.0.0.0:5000/&lt;/code&gt;. This route will do nothing
5149more than render &lt;code&gt;frontend.html&lt;/code&gt; template. This is done by &lt;code&gt;return bottle.template(&amp;quot;frontend.html&amp;quot;)&lt;/code&gt;. Check code below to further examine how
5150exactly this is done.&lt;/p&gt;
5151&lt;p&gt;Now we will expand &lt;code&gt;/api&lt;/code&gt; route and use different methods to write or read
5152data-points. For writing data-point we will use POST method and for reading
5153points we will use GET method. GET method will return JSON object with latest
5154readings and historical data.&lt;/p&gt;
5155&lt;p&gt;There is a fantastic JavaScript library for plotting time-series charts called
5156&lt;a href=&#34;https://www.metricsgraphicsjs.org&#34;&gt;MetricsGraphics.js&lt;/a&gt; that is based on
5157&lt;a href=&#34;https://d3js.org/&#34;&gt;D3.js&lt;/a&gt; library for visualizing data.&lt;/p&gt;
5158&lt;p&gt;Data schema required by MetricsGraphics.js → to achieve this we need to
5159transform data from database into this format:&lt;/p&gt;
5160&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;[
5161&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; {
5162&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;date&amp;#34;: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;2017-08-11 01:07:20&amp;#34;&lt;/span&gt;,
5163&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;value&amp;#34;: 933
5164&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; },
5165&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; {
5166&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;date&amp;#34;: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;2017-08-11 01:07:30&amp;#34;&lt;/span&gt;,
5167&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;value&amp;#34;: 743
5168&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5169&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;]
5170&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Web application is now complete and we only need &lt;code&gt;frontend.html&lt;/code&gt; that we
5171will develop now. If you would try to start web app now and go to root app this
5172will return error because we don&#39;t have frontend.html yet.&lt;/p&gt;
5173&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# -*- coding: utf-8 -*-&lt;/span&gt;
5174&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5175&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; time
5176&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; bottle
5177&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; json
5178&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; datetime
5179&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; random
5180&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; dataset
5181&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5182&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# initializing bottle app&lt;/span&gt;
5183&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;app = bottle.Bottle()
5184&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5185&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# adds root directory as template folder&lt;/span&gt;
5186&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;bottle.TEMPLATE_PATH.insert(0, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;./&amp;#34;&lt;/span&gt;)
5187&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5188&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# connects to sqlite database&lt;/span&gt;
5189&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# check_same_thread=False allows using it in multi-threaded mode&lt;/span&gt;
5190&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;app.config[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;db&amp;#34;&lt;/span&gt;] = dataset.connect(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;sqlite:///data.db?check_same_thread=False&amp;#34;&lt;/span&gt;)
5191&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5192&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# api key that will be used in Arduino code&lt;/span&gt;
5193&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;app.config[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;api_key&amp;#34;&lt;/span&gt;] = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;JtF2aUE5SGHfVJBCG5SH&amp;#34;&lt;/span&gt;
5194&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5195&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# triggered when / is accessed from browser&lt;/span&gt;
5196&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# only accepts GET → no POST allowed&lt;/span&gt;
5197&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@app.route(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;/&amp;#34;&lt;/span&gt;, method=[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;GET&amp;#34;&lt;/span&gt;])
5198&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;def&lt;/span&gt; route_default():
5199&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt; bottle.template(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;frontend.html&amp;#34;&lt;/span&gt;)
5200&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5201&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# triggered when /api is accessed from browser&lt;/span&gt;
5202&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# accepts POST and GET&lt;/span&gt;
5203&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@app.route(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;/api&amp;#34;&lt;/span&gt;, method=[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;GET&amp;#34;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;POST&amp;#34;&lt;/span&gt;])
5204&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;def&lt;/span&gt; route_default():
5205&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5206&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;# if method is POST then we write datapoint&lt;/span&gt;
5207&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; bottle.request.method == &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;POST&amp;#34;&lt;/span&gt;:
5208&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; status = 400
5209&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; ts = int(time.time()) &lt;span style=&#34;color:#008000&#34;&gt;# current timestamp&lt;/span&gt;
5210&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; value = bottle.request.body.read() &lt;span style=&#34;color:#008000&#34;&gt;# data from device&lt;/span&gt;
5211&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; api_key = bottle.request.get_header(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Api-Key&amp;#34;&lt;/span&gt;) &lt;span style=&#34;color:#008000&#34;&gt;# api key from header&lt;/span&gt;
5212&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5213&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;# outputs to console recieved data for debug reason&lt;/span&gt;
5214&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; print &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&amp;gt;&amp;gt;&amp;gt; &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;{}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; :: &lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;{}&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&lt;/span&gt;.format(value, api_key)
5215&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5216&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;# if api_key is correct and value is present&lt;/span&gt;
5217&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;# then writes attribute to point table&lt;/span&gt;
5218&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; api_key == app.config[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;api_key&amp;#34;&lt;/span&gt;] &lt;span style=&#34;color:#00f&#34;&gt;and&lt;/span&gt; value:
5219&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; app.config[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;db&amp;#34;&lt;/span&gt;][&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;point&amp;#34;&lt;/span&gt;].insert(dict(ts=ts, value=value))
5220&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; status = 200
5221&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5222&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;# we only need to return status&lt;/span&gt;
5223&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt; bottle.HTTPResponse(status=status, body=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;&amp;#34;&lt;/span&gt;)
5224&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5225&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;# if method is GET then we read datapoint&lt;/span&gt;
5226&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;else&lt;/span&gt;:
5227&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; response = []
5228&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; datapoints = app.config[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;db&amp;#34;&lt;/span&gt;][&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;point&amp;#34;&lt;/span&gt;].all()
5229&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5230&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; point &lt;span style=&#34;color:#00f&#34;&gt;in&lt;/span&gt; datapoints:
5231&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; response.append({
5232&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;date&amp;#34;&lt;/span&gt;: datetime.datetime.fromtimestamp(int(point[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;ts&amp;#34;&lt;/span&gt;])).strftime(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;%Y-%m-&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt;%d&lt;/span&gt;&lt;span style=&#34;color:#a31515&#34;&gt; %H:%M:%S&amp;#34;&lt;/span&gt;),
5233&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;value&amp;#34;&lt;/span&gt;: point[&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;value&amp;#34;&lt;/span&gt;]
5234&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; })
5235&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5236&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; bottle.response.content_type = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;application/json&amp;#34;&lt;/span&gt;
5237&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt; json.dumps(response)
5238&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5239&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# starting server on http://0.0.0.0:5000&lt;/span&gt;
5240&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; __name__ == &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;__main__&amp;#34;&lt;/span&gt;:
5241&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; bottle.run(
5242&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; app = app,
5243&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; host = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;0.0.0.0&amp;#34;&lt;/span&gt;,
5244&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; port = 5000,
5245&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; debug = &lt;span style=&#34;color:#00f&#34;&gt;True&lt;/span&gt;,
5246&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; reloader = &lt;span style=&#34;color:#00f&#34;&gt;True&lt;/span&gt;,
5247&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; catchall = &lt;span style=&#34;color:#00f&#34;&gt;True&lt;/span&gt;,
5248&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; )
5249&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;And now finally we can implement &lt;code&gt;frontend.html&lt;/code&gt;. Create file with this name
5250and copy code below. When you are done you can start web application. Steps for
5251this part are listed below the code.&lt;/p&gt;
5252&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;&amp;lt;!DOCTYPE html&amp;gt;&lt;/span&gt;
5253&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;lt;html&amp;gt;
5254&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5255&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;head&amp;gt;
5256&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;meta charset=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;utf-8&amp;#34;&lt;/span&gt;&amp;gt;
5257&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;title&amp;gt;Simple IOT application&amp;lt;/title&amp;gt;
5258&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/head&amp;gt;
5259&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5260&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;body&amp;gt;
5261&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5262&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;h1&amp;gt;Simple IOT application&amp;lt;/h1&amp;gt;
5263&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5264&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;div class=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;chart-placeholder&amp;#34;&lt;/span&gt;&amp;gt;
5265&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;div id=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;chart&amp;#34;&lt;/span&gt;&amp;gt;&amp;lt;/div&amp;gt;
5266&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/div&amp;gt;
5267&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5268&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;&amp;lt;!-- application main script --&amp;gt;&lt;/span&gt;
5269&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;script src=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js&amp;#34;&lt;/span&gt;&amp;gt;&amp;lt;/script&amp;gt;
5270&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;script src=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;https://cdnjs.cloudflare.com/ajax/libs/d3/4.10.0/d3.min.js&amp;#34;&lt;/span&gt;&amp;gt;&amp;lt;/script&amp;gt;
5271&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;script src=&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;https://cdnjs.cloudflare.com/ajax/libs/metrics-graphics/2.11.0/metricsgraphics.min.js&amp;#34;&lt;/span&gt;&amp;gt;&amp;lt;/script&amp;gt;
5272&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;script&amp;gt;
5273&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;function&lt;/span&gt; fetch_and_render() {
5274&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; d3.json(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;/api&amp;#34;&lt;/span&gt;, &lt;span style=&#34;color:#00f&#34;&gt;function&lt;/span&gt;(data) {
5275&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; data = MG.convert.date(data, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;date&amp;#34;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;%Y-%m-%d %H:%M:%S&amp;#34;&lt;/span&gt;);
5276&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; MG.data_graphic({
5277&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; data: data,
5278&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; chart_type: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;line&amp;#34;&lt;/span&gt;,
5279&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; full_width: &lt;span style=&#34;color:#00f&#34;&gt;true&lt;/span&gt;,
5280&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; height: 270,
5281&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; target: document.getElementById(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;chart&amp;#34;&lt;/span&gt;),
5282&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; x_accessor: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;date&amp;#34;&lt;/span&gt;,
5283&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; y_accessor: &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;value&amp;#34;&lt;/span&gt;
5284&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; });
5285&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; });
5286&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5287&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; window.onload = &lt;span style=&#34;color:#00f&#34;&gt;function&lt;/span&gt;() {
5288&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// initial call for rendering
5289&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; fetch_and_render();
5290&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5291&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;// updates chart every 5 seconds
5292&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt; setInterval(&lt;span style=&#34;color:#00f&#34;&gt;function&lt;/span&gt;() {
5293&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; fetch_and_render();
5294&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }, 5000);
5295&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5296&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/script&amp;gt;
5297&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5298&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;&amp;lt;!-- application styles --&amp;gt;&lt;/span&gt;
5299&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;style&amp;gt;
5300&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; body {
5301&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;font&lt;/span&gt;: 13&lt;span style=&#34;color:#2b91af&#34;&gt;px&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;sans-serif&lt;/span&gt;;
5302&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;padding&lt;/span&gt;: 20&lt;span style=&#34;color:#2b91af&#34;&gt;px&lt;/span&gt; 50&lt;span style=&#34;color:#2b91af&#34;&gt;px&lt;/span&gt;;
5303&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5304&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; .&lt;span style=&#34;color:#2b91af&#34;&gt;chart-placeholder&lt;/span&gt; {
5305&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;border&lt;/span&gt;: 2&lt;span style=&#34;color:#2b91af&#34;&gt;px&lt;/span&gt; &lt;span style=&#34;color:#00f&#34;&gt;solid&lt;/span&gt; #ccc;
5306&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;width&lt;/span&gt;: 100&lt;span style=&#34;color:#2b91af&#34;&gt;%&lt;/span&gt;;
5307&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;user-select&lt;/span&gt;: &lt;span style=&#34;color:#00f&#34;&gt;none&lt;/span&gt;;
5308&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5309&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#008000&#34;&gt;/* chart styles */&lt;/span&gt;
5310&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; .&lt;span style=&#34;color:#2b91af&#34;&gt;mg-line1-color&lt;/span&gt; {
5311&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; stroke: &lt;span style=&#34;color:#00f&#34;&gt;red&lt;/span&gt;;
5312&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; stroke-width: 2;
5313&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5314&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; .&lt;span style=&#34;color:#2b91af&#34;&gt;mg-main-area&lt;/span&gt;, .&lt;span style=&#34;color:#2b91af&#34;&gt;mg-main-line&lt;/span&gt; {
5315&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; fill: #fff;
5316&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5317&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; .&lt;span style=&#34;color:#2b91af&#34;&gt;mg-x-axis&lt;/span&gt; line, .&lt;span style=&#34;color:#2b91af&#34;&gt;mg-y-axis&lt;/span&gt; line {
5318&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; stroke: #b3b2b2;
5319&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; stroke-width: 1&lt;span style=&#34;color:#2b91af&#34;&gt;px&lt;/span&gt;;
5320&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5321&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/style&amp;gt;
5322&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5323&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;/body&amp;gt;
5324&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5325&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&amp;lt;/html&amp;gt;
5326&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Now the folder structure should look like:&lt;/p&gt;
5327&lt;p&gt;&lt;em&gt;simple-iot-app/&lt;/em&gt;&lt;/p&gt;
5328&lt;ul&gt;
5329&lt;li&gt;&lt;em&gt;webapp.py&lt;/em&gt;&lt;/li&gt;
5330&lt;li&gt;&lt;em&gt;data.db&lt;/em&gt;&lt;/li&gt;
5331&lt;li&gt;&lt;em&gt;frontend.html&lt;/em&gt;&lt;/li&gt;
5332&lt;/ul&gt;
5333&lt;p&gt;Ok, lets now start application and start feeding it data.&lt;/p&gt;
5334&lt;ol&gt;
5335&lt;li&gt;&lt;code&gt;python webapp.py&lt;/code&gt;&lt;/li&gt;
5336&lt;li&gt;connect Arduino MKR1000 to power source&lt;/li&gt;
5337&lt;li&gt;open browser and go to &lt;code&gt;http://0.0.0.0:5000&lt;/code&gt;&lt;/li&gt;
5338&lt;/ol&gt;
5339&lt;p&gt;If everything goes well you should be seeing new data-points rendered on chart
5340every 5 seconds.&lt;/p&gt;
5341&lt;p&gt;If you navigate to &lt;code&gt;http://0.0.0.0:5000&lt;/code&gt; you should see rendered chart as
5342shown on picture below.&lt;/p&gt;
5343&lt;figure&gt;
5344&lt;img src=&#34;/posts/iot-application/iot-app-output.png&#34; alt=&#34;Application output&#34; /&gt;
5345&lt;/figure&gt;
5346&lt;p&gt;Complete application with all the code is available for
5347&lt;a href=&#34;/posts/iot-application/simple-iot-application.zip&#34;&gt;download&lt;/a&gt;.&lt;/p&gt;
5348&lt;h2 id=&#34;conclusion&#34;&gt;Conclusion&lt;/h2&gt;
5349&lt;p&gt;I hope this clarifies some aspects of IOT application development. Of course
5350this is a minimal example and is far from what can be done in real life with
5351some further dive into other technologies.&lt;/p&gt;
5352&lt;p&gt;If you would like to continue exploring IOT world here are some interesting
5353resources for you to examine:&lt;/p&gt;
5354&lt;ul&gt;
5355&lt;li&gt;&lt;a href=&#34;https://www.allaboutcircuits.com/projects/reading-sensors-with-an-arduino/&#34;&gt;Reading Sensors with an Arduino&lt;/a&gt;&lt;/li&gt;
5356&lt;li&gt;&lt;a href=&#34;http://www.hivemq.com/blog/how-to-get-started-with-mqtt&#34;&gt;MQTT 101 – How to Get Started with the lightweight IoT Protocol&lt;/a&gt;&lt;/li&gt;
5357&lt;li&gt;&lt;a href=&#34;https://www.html5rocks.com/en/tutorials/eventsource/basics/&#34;&gt;Stream Updates with Server-Sent Events&lt;/a&gt;&lt;/li&gt;
5358&lt;li&gt;&lt;a href=&#34;http://www.tutorialspoint.com/internet_of_things/&#34;&gt;Internet of Things (IoT) Tutorials&lt;/a&gt;&lt;/li&gt;
5359&lt;/ul&gt;
5360&lt;p&gt;Any comment or additional ideas are welcomed in comments below.&lt;/p&gt;
5361</content:encoded>
5362 </item>
5363
5364
5365
5366 <item>
5367 <title>Profiling Python web applications with visual tools</title>
5368 <link>https://mitjafelicijan.com/profiling-python-web-applications-with-visual-tools.html</link>
5369 <pubDate>Fri, 21 Apr 2017 12:00:00 &#43;0200</pubDate>
5370 <guid>https://mitjafelicijan.com/profiling-python-web-applications-with-visual-tools.html</guid>
5371 <description>I have been profiling my software with KCachegrind for a long time now and I wasmissing this option when I am developing API&amp;#39;s or other web services.</description>
5372 <content:encoded>&lt;p&gt;I have been profiling my software with KCachegrind for a long time now and I was
5373missing this option when I am developing API&#39;s or other web services. I always
5374knew that this is possible but never really took the time and dive into it.&lt;/p&gt;
5375&lt;p&gt;Before we begin there are some requirements. We will need to:&lt;/p&gt;
5376&lt;ul&gt;
5377&lt;li&gt;implement &lt;a href=&#34;https://docs.python.org/2/library/profile.html#module-cProfile&#34;&gt;cProfile&lt;/a&gt; into our web app,&lt;/li&gt;
5378&lt;li&gt;convert output to &lt;a href=&#34;http://valgrind.org/docs/manual/cl-manual.html&#34;&gt;callgrind&lt;/a&gt; format with &lt;a href=&#34;https://pypi.python.org/pypi/pyprof2calltree/&#34;&gt;pyprof2calltree&lt;/a&gt;,&lt;/li&gt;
5379&lt;li&gt;visualize data with &lt;a href=&#34;http://kcachegrind.sourceforge.net/html/Home.html&#34;&gt;KCachegrind&lt;/a&gt; or &lt;a href=&#34;http://www.profilingviewer.com/&#34;&gt;Profiling Viewer&lt;/a&gt;.&lt;/li&gt;
5380&lt;/ul&gt;
5381&lt;p&gt;If you are using MacOS you should check out &lt;a href=&#34;http://www.profilingviewer.com/&#34;&gt;Profiling
5382Viewer&lt;/a&gt; or
5383&lt;a href=&#34;http://www.maccallgrind.com/&#34;&gt;MacCallGrind&lt;/a&gt;.&lt;/p&gt;
5384&lt;figure&gt;
5385&lt;img src=&#34;/posts/python-profiling/kcachegrind.png&#34; alt=&#34;KCachegrind&#34; /&gt;
5386&lt;/figure&gt;
5387&lt;p&gt;We will be dividing this post into two main categories:&lt;/p&gt;
5388&lt;ul&gt;
5389&lt;li&gt;writing simple web-service,&lt;/li&gt;
5390&lt;li&gt;visualize profile of this web-service.&lt;/li&gt;
5391&lt;/ul&gt;
5392&lt;h2 id=&#34;simple-web-service&#34;&gt;Simple web-service&lt;/h2&gt;
5393&lt;p&gt;Let&#39;s use virtualenv so we won&#39;t pollute our base system. If you don&#39;t have
5394virtualenv installed on your system you can install it with pip command.&lt;/p&gt;
5395&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# let&amp;#39;s install virtualenv globally&lt;/span&gt;
5396&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ sudo pip install virtualenv
5397&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5398&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# let&amp;#39;s also install pyprof2calltree globally&lt;/span&gt;
5399&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ sudo pip install pyprof2calltree
5400&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5401&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# now we create project&lt;/span&gt;
5402&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ mkdir demo-project
5403&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ cd demo-project/
5404&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5405&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# now let&amp;#39;s create folder where we will store profiles&lt;/span&gt;
5406&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ mkdir prof
5407&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5408&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# now we create empty virtualenv in venv/ folder&lt;/span&gt;
5409&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ virtualenv --no-site-packages venv
5410&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5411&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# we now need to activate virtualenv&lt;/span&gt;
5412&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ source venv/bin/activate
5413&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5414&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# you can check if virtualenv was correctly initialized by&lt;/span&gt;
5415&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# checking where your python interpreter is located&lt;/span&gt;
5416&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# if command bellow points to your created directory and not some&lt;/span&gt;
5417&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# system dir like /usr/bin/python then everything is fine&lt;/span&gt;
5418&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ which python
5419&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5420&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# we can check now if all is good ➜ if ok couple of&lt;/span&gt;
5421&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# lines will be displayed&lt;/span&gt;
5422&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ pip freeze
5423&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# appdirs==1.4.3&lt;/span&gt;
5424&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# packaging==16.8&lt;/span&gt;
5425&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# pyparsing==2.2.0&lt;/span&gt;
5426&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# six==1.10.0&lt;/span&gt;
5427&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5428&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# now we are ready to install bottlepy ➜ web micro-framework&lt;/span&gt;
5429&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ pip install bottle
5430&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5431&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# you can deactivate virtualenv but you will then go&lt;/span&gt;
5432&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# under system domain ➜ for now don&amp;#39;t deactivate&lt;/span&gt;
5433&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ deactivate
5434&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;We are now ready to write simple web service. Let&#39;s create file app.py and paste
5435code bellow in this newly created file.&lt;/p&gt;
5436&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# -*- coding: utf-8 -*-&lt;/span&gt;
5437&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5438&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; bottle
5439&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; random
5440&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; cProfile
5441&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5442&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;app = bottle.Bottle()
5443&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5444&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# this function is a decorator and encapsulates function&lt;/span&gt;
5445&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# and performs profiling and then saves it to subfolder&lt;/span&gt;
5446&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# prof/function-name.prof&lt;/span&gt;
5447&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# in our example only awesome_random_number function will&lt;/span&gt;
5448&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# be profiled because it has do_cprofile defined&lt;/span&gt;
5449&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;def&lt;/span&gt; do_cprofile(func):
5450&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;def&lt;/span&gt; profiled_func(*args, **kwargs):
5451&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; profile = cProfile.Profile()
5452&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;try&lt;/span&gt;:
5453&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; profile.enable()
5454&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; result = func(*args, **kwargs)
5455&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; profile.disable()
5456&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt; result
5457&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;finally&lt;/span&gt;:
5458&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; profile.dump_stats(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;prof/&amp;#34;&lt;/span&gt; &#43; str(func.__name__) &#43; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;.prof&amp;#34;&lt;/span&gt;)
5459&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt; profiled_func
5460&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5461&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5462&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# we use profiling over specific function with including&lt;/span&gt;
5463&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# @do_cprofile above function declaration&lt;/span&gt;
5464&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@app.route(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;/&amp;#34;&lt;/span&gt;)
5465&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@do_cprofile
5466&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;def&lt;/span&gt; awesome_random_number():
5467&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; awesome_random_number = random.randint(0, 100)
5468&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;awesome random number is &amp;#34;&lt;/span&gt; &#43; str(awesome_random_number)
5469&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5470&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;@app.route(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;/test&amp;#34;&lt;/span&gt;)
5471&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;def&lt;/span&gt; test():
5472&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;dummy test&amp;#34;&lt;/span&gt;
5473&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5474&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;if&lt;/span&gt; __name__ == &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#39;__main__&amp;#39;&lt;/span&gt;:
5475&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; bottle.run(
5476&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; app = app,
5477&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; host = &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;0.0.0.0&amp;#34;&lt;/span&gt;,
5478&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; port = 4000
5479&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; )
5480&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5481&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# run with &amp;#39;python app.py&amp;#39;&lt;/span&gt;
5482&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# open browser &amp;#39;http://0.0.0.0:4000&amp;#39;&lt;/span&gt;
5483&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;When browser hits awesome_random_number() function profile is created in prof/
5484subfolder.&lt;/p&gt;
5485&lt;h2 id=&#34;visualize-profile&#34;&gt;Visualize profile&lt;/h2&gt;
5486&lt;p&gt;Now let&#39;s create callgrind format from this cProfile output.&lt;/p&gt;
5487&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ cd prof/
5488&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ pyprof2calltree -i awesome_random_number.prof
5489&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# this creates &amp;#39;awesome_random_number.prof.log&amp;#39; file in the same folder&lt;/span&gt;
5490&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;This file can be opened with visualizing tools listed above. In this case we
5491will be using Profilling Viewer under MacOS. You can open image in new tab. As
5492you can see from this example there is hierarchy of execution order of your
5493code.&lt;/p&gt;
5494&lt;figure&gt;
5495&lt;img src=&#34;/posts/python-profiling/profiling-viewer.png&#34; alt=&#34;Profilling Viewer&#34; /&gt;
5496&lt;/figure&gt;
5497&lt;blockquote&gt;
5498&lt;p&gt;Make sure you convert output of the cProfile output every time you want to
5499refresh and take a look at your possible optimizations because cProfile updates
5500.prof file every time browser hits the function.&lt;/p&gt;
5501&lt;/blockquote&gt;
5502&lt;p&gt;This is just a simple example but when you are developing real-life applications
5503this can be very illuminating, especially to see which parts of your code are
5504bottlenecks and need to be optimized.&lt;/p&gt;
5505&lt;h2 id=&#34;update-2017-04-22&#34;&gt;Update 2017-04-22&lt;/h2&gt;
5506&lt;p&gt;Reddit user &lt;a href=&#34;https://www.reddit.com/user/mvt&#34;&gt;mvt&lt;/a&gt; also recommended this awesome
5507web based profile visualizer &lt;a href=&#34;https://jiffyclub.github.io/snakeviz/&#34;&gt;SnakeViz&lt;/a&gt;
5508that directly takes output from
5509&lt;a href=&#34;https://docs.python.org/2/library/profile.html#module-cProfile&#34;&gt;cProfile&lt;/a&gt;
5510module.&lt;/p&gt;
5511&lt;div class=&#34;reddit-embed&#34; data-embed-media=&#34;www.redditmedia.com&#34; data-embed-parent=&#34;false&#34; data-embed-live=&#34;false&#34; data-embed-uuid=&#34;583880c1-002e-41ed-a373-020a0ef2cff9&#34; data-embed-created=&#34;2017-04-22T19:46:54.810Z&#34;&gt;&lt;a href=&#34;https://www.reddit.com/r/Python/comments/66v373/profiling_python_web_applications_with_visual/dgljhsb/&#34;&gt;Comment&lt;/a&gt; from discussion &lt;a href=&#34;https://www.reddit.com/r/Python/comments/66v373/profiling_python_web_applications_with_visual/&#34;&gt;Profiling Python web applications with visual tools&lt;/a&gt;.&lt;/div&gt;&lt;script async src=&#34;https://www.redditstatic.com/comment-embed.js&#34;&gt;&lt;/script&gt;
5512&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# let&amp;#39;s install it globally as well&lt;/span&gt;
5513&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ sudo pip install snakeviz
5514&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5515&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# now let&amp;#39;s visualize&lt;/span&gt;
5516&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ cd prof/
5517&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ snakeviz awesome_random_number.prof
5518&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# this automatically opens browser window and&lt;/span&gt;
5519&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# shows visualized profile&lt;/span&gt;
5520&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;figure&gt;
5521&lt;img src=&#34;/posts/python-profiling/snakeviz.png&#34; alt=&#34;SnakeViz&#34; /&gt;
5522&lt;/figure&gt;
5523&lt;p&gt;Reddit user &lt;a href=&#34;https://www.reddit.com/user/ccharles&#34;&gt;ccharles&lt;/a&gt; suggested a better
5524way for installing pip software by targeting user level instead of using sudo.&lt;/p&gt;
5525&lt;div class=&#34;reddit-embed&#34; data-embed-media=&#34;www.redditmedia.com&#34; data-embed-parent=&#34;false&#34; data-embed-live=&#34;false&#34; data-embed-uuid=&#34;f4f0459e-684d-441e-bebe-eb49b2f0a31d&#34; data-embed-created=&#34;2017-04-22T19:46:10.874Z&#34;&gt;&lt;a href=&#34;https://www.reddit.com/r/Python/comments/66v373/profiling_python_web_applications_with_visual/dglpzkx/&#34;&gt;Comment&lt;/a&gt; from discussion &lt;a href=&#34;https://www.reddit.com/r/Python/comments/66v373/profiling_python_web_applications_with_visual/&#34;&gt;Profiling Python web applications with visual tools&lt;/a&gt;.&lt;/div&gt;&lt;script async src=&#34;https://www.redditstatic.com/comment-embed.js&#34;&gt;&lt;/script&gt;
5526&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# now we need to add this path to our $PATH variable&lt;/span&gt;
5527&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# we do this my adding this line at the end of your&lt;/span&gt;
5528&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# ~/.bashrc file&lt;/span&gt;
5529&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;PATH=$PATH:$HOME/.local/bin/
5530&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5531&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# in order to use this new configuration you can close&lt;/span&gt;
5532&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# and reopen terminal or reload .bashrc file&lt;/span&gt;
5533&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ source ~/.bashrc
5534&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5535&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# now let&amp;#39;s test if new directory is present in $PATH&lt;/span&gt;
5536&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ echo $PATH
5537&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5538&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# now we can install on user level by adding --user&lt;/span&gt;
5539&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# without use of sudo&lt;/span&gt;
5540&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;$ pip install snakeviz --user
5541&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Or as suggested by &lt;a href=&#34;https://www.reddit.com/user/mvt&#34;&gt;mvt&lt;/a&gt; you can
5542use &lt;a href=&#34;https://github.com/mitsuhiko/pipsi&#34;&gt;pipsi&lt;/a&gt;.&lt;/p&gt;
5543</content:encoded>
5544 </item>
5545
5546
5547
5548 <item>
5549 <title>What I&#39;ve learned developing ad server</title>
5550 <link>https://mitjafelicijan.com/what-i-ve-learned-developing-ad-server.html</link>
5551 <pubDate>Mon, 17 Apr 2017 12:00:00 &#43;0200</pubDate>
5552 <guid>https://mitjafelicijan.com/what-i-ve-learned-developing-ad-server.html</guid>
5553 <description>For the past year and half I have been developing native advertising server thatcontextually matches ads and displays them in different template forms onvariety of websites.</description>
5554 <content:encoded>&lt;p&gt;For the past year and half I have been developing native advertising server that
5555contextually matches ads and displays them in different template forms on
5556variety of websites. This project grew from serving thousands of ads per day to
5557millions.&lt;/p&gt;
5558&lt;p&gt;The system is made from couple of core components:&lt;/p&gt;
5559&lt;ul&gt;
5560&lt;li&gt;API for serving ads,&lt;/li&gt;
5561&lt;li&gt;Utils - cronjobs and queue management tools,&lt;/li&gt;
5562&lt;li&gt;Dashboard UI.&lt;/li&gt;
5563&lt;/ul&gt;
5564&lt;p&gt;Initial release was using &lt;a href=&#34;https://www.mongodb.com/&#34;&gt;MongoDB&lt;/a&gt; for full-text
5565search but was later replaced by &lt;a href=&#34;https://www.elastic.co/&#34;&gt;Elasticsearch&lt;/a&gt; for
5566better CPU utilization and better search performance. This provided us with many
5567amazing functionalities of &lt;a href=&#34;https://www.elastic.co/&#34;&gt;Elasticsearch&lt;/a&gt;. You should
5568check it out if you do any search related operations.&lt;/p&gt;
5569&lt;p&gt;Because the premise of the server is to provide native ad experience, they are
5570rendered on the client side via simple templating engine. This ensures that ads
5571can be displayed number of different ways based on the visual style of the
5572page. And this makes JavaScript client library quite complex.&lt;/p&gt;
5573&lt;p&gt;So now that you know basic information about the product lets get into the
5574lessons we learned.&lt;/p&gt;
5575&lt;h2 id=&#34;aggregate-everything&#34;&gt;Aggregate everything&lt;/h2&gt;
5576&lt;p&gt;After beta version was released everything (impressions, clicks, etc) was
5577written in nanosecond resolution in the database. At that time we were using
5578&lt;a href=&#34;https://www.postgresql.org/&#34;&gt;PostgreSQL&lt;/a&gt; and database quickly grew way above
5579200GB in disk space. And that was problematic. Statistics took disturbingly long
5580time to aggregate. Also using indexes on stats table in database was no help
5581after we reached 500 million datapoints.&lt;/p&gt;
5582&lt;blockquote&gt;
5583&lt;p&gt;There is a marketing product information and there is real life experience.
5584And the tend to be quite the opposite.&lt;/p&gt;
5585&lt;/blockquote&gt;
5586&lt;p&gt;This was the reason that now everything is aggregated on daily basis and this
5587data is then fed to Elastic in form of daily summary. With this we achieved we
5588can now track many more dimensions such as zone, channel and platform
5589information. And with this information we can now adapt occurrences of ads on
5590specific places more precisely.&lt;/p&gt;
5591&lt;p&gt;We have also adapted &lt;a href=&#34;https://redis.io/&#34;&gt;Redis&lt;/a&gt; as a full-time citizen in our
5592stack. Because Redis also stores information on a local disk we have some sort
5593of backup if server would accidentally suffer some failure.&lt;/p&gt;
5594&lt;p&gt;All the real-time statistics for ad serving and redirecting is presented as
5595counters in Redis instance and daily extracted and pushed to Elastic.&lt;/p&gt;
5596&lt;h2 id=&#34;measure-everything&#34;&gt;Measure everything&lt;/h2&gt;
5597&lt;p&gt;The thing about software is that we really don&#39;t know how well it is performing
5598under load until such load is presented. When testing locally everything is fine
5599but when on production things tend to fall apart.&lt;/p&gt;
5600&lt;p&gt;As a solution for this we are measuring everything we can. Function execution
5601time (by encapsulating functions with timers), server performance (cpu, memory,
5602disk, etc), Nginx and &lt;a href=&#34;https://uwsgi-docs.readthedocs.io/&#34;&gt;uWSGI&lt;/a&gt; performance.
5603We sacrifice a bit of performance for the sake of this information. And we store
5604all this information for later analysis.&lt;/p&gt;
5605&lt;p&gt;&lt;strong&gt;Example of function execution time&lt;/strong&gt;&lt;/p&gt;
5606&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;{
5607&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;get_final_filtered_ads&amp;#34;: {
5608&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;counter&amp;#34;: 1931250,
5609&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;avg&amp;#34;: 0.0066143431,
5610&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;elapsed&amp;#34;: 12773.9500310003
5611&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; },
5612&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;store_keywords_statistics&amp;#34;: {
5613&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;counter&amp;#34;: 1931011,
5614&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;avg&amp;#34;: 0.0004605267,
5615&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;elapsed&amp;#34;: 889.2821669996
5616&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; },
5617&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;match_by_context&amp;#34;: {
5618&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;counter&amp;#34;: 1931011,
5619&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;avg&amp;#34;: 0.0055960716,
5620&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;elapsed&amp;#34;: 10806.0758889999
5621&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; },
5622&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;match_by_high_performance&amp;#34;: {
5623&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;counter&amp;#34;: 262,
5624&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;avg&amp;#34;: 0.0152770229,
5625&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;elapsed&amp;#34;: 4.00258
5626&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; },
5627&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;store_impression_stats&amp;#34;: {
5628&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;counter&amp;#34;: 1931250,
5629&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;avg&amp;#34;: 0.0006189991,
5630&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;#34;elapsed&amp;#34;: 1195.4419869999
5631&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5632&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
5633&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;We have also started profiling with &lt;a href=&#34;https://pymotw.com/2/profile/&#34;&gt;cProfile&lt;/a&gt;
5634and then visualizing with &lt;a href=&#34;http://kcachegrind.sourceforge.net/&#34;&gt;KCachegrind&lt;/a&gt;.
5635This provides much more detailed look into code execution.&lt;/p&gt;
5636&lt;h2 id=&#34;cache-control-is-your-friend&#34;&gt;Cache control is your friend&lt;/h2&gt;
5637&lt;p&gt;Because we use Javascript library for rendering ads we rely on this script
5638extensively and when in need we need to be able to change behavior of the script
5639quickly.&lt;/p&gt;
5640&lt;p&gt;In our case we can not simply replace javascript url in html code. It usually
5641takes a day or two for the guys who maintain sites to change code or add
5642?ver=xxx attribute. And this makes rapid deployment and testing very difficult
5643and time consuming. There is a limitation of how much you can test locally.&lt;/p&gt;
5644&lt;p&gt;We are now in the process of integrating &lt;a href=&#34;https://www.google.com/analytics/tag-manager/&#34;&gt;Google Tag
5645Manager&lt;/a&gt; but couple of websites
5646are developed on ASP.net platform that have some problems with tag manager. With
5647a solution below we are certain that we are serving latest version of the
5648script.&lt;/p&gt;
5649&lt;p&gt;And it only takes one mistake and users have the script cached and in case of
5650caching it for 1 year you probably know where the problem is.&lt;/p&gt;
5651&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# nginx ➜ /etc/nginx/sites-available/default
5652&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;&lt;/span&gt;&lt;span style=&#34;color:#00f&#34;&gt;location&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;/static/&lt;/span&gt; {
5653&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;alias&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;/path-to-static-content/&lt;/span&gt;;
5654&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;autoindex&lt;/span&gt; off;
5655&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;charset&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;utf-8&lt;/span&gt;;
5656&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;gzip&lt;/span&gt; on;
5657&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;gzip_types&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;text/plain&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;application/javascript&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;application/x-javascript&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;text/javascript&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;text/xml&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;text/css&lt;/span&gt;;
5658&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;location&lt;/span&gt; ~&lt;span style=&#34;color:#a31515&#34;&gt;*&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;\.(ico|gif|jpeg|jpg|png|woff|ttf|otf|svg|woff2|eot)&lt;/span&gt;$ {
5659&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;expires&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;1y&lt;/span&gt;;
5660&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;add_header&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;Pragma&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;public&lt;/span&gt;;
5661&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;add_header&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;Cache-Control&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;public&amp;#34;&lt;/span&gt;;
5662&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5663&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;location&lt;/span&gt; ~&lt;span style=&#34;color:#a31515&#34;&gt;*&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;\.(css|js|txt)&lt;/span&gt;$ {
5664&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;expires&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;3600s&lt;/span&gt;;
5665&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;add_header&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;Pragma&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;public&lt;/span&gt;;
5666&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;add_header&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;Cache-Control&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;public,&lt;/span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;must-revalidate&amp;#34;&lt;/span&gt;;
5667&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5668&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
5669&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;Also be careful when redirecting to url in your python code. We noticed that if
5670we didn&#39;t precisely setup cache control and expire headers in response we didn&#39;t
5671get the request on the server and therefore couldn&#39;t measure clicks. So when
5672redirecting do as follows and there will be no problems.&lt;/p&gt;
5673&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# python ➜ bottlepy web micro-framework&lt;/span&gt;
5674&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;response = bottle.HTTPResponse(status=302)
5675&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;response.set_header(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Cache-Control&amp;#34;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;no-store, no-cache, must-revalidate&amp;#34;&lt;/span&gt;)
5676&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;response.set_header(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Expires&amp;#34;&lt;/span&gt;, &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Thu, 01 Jan 1970 00:00:00 GMT&amp;#34;&lt;/span&gt;)
5677&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;response.set_header(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;Location&amp;#34;&lt;/span&gt;, url)
5678&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;return&lt;/span&gt; response
5679&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;blockquote&gt;
5680&lt;p&gt;Cache control in browsers is quite aggressive and you need to be precise to
5681avoid future problems. We learned that lesson the hard way.&lt;/p&gt;
5682&lt;/blockquote&gt;
5683&lt;h2 id=&#34;learn-nginx&#34;&gt;Learn NGINX&lt;/h2&gt;
5684&lt;p&gt;When deciding on a web server we went with Nginx as a reverse proxy for our
5685applications. We adapted micro-service oriented architecture early in the
5686project to ensure when we scale we can easily add additional servers to our
5687cluster. And Nginx was crucial to perform load balancing and static content
5688delivery.&lt;/p&gt;
5689&lt;p&gt;At first our config file was quite simple and later grew larger. After patching
5690and adding new settings I sat down and learned more about the guts of Nginx.
5691This proved to be very useful and we were able to squeeze much more out of our
5692setup. So I advise you to take your time and read through the
5693&lt;a href=&#34;https://nginx.org/en/docs/&#34;&gt;documentation&lt;/a&gt;. This saved us a lot of headache.
5694Googling for solutions only goes so far.&lt;/p&gt;
5695&lt;h2 id=&#34;use-redismemcached&#34;&gt;Use Redis/Memcached&lt;/h2&gt;
5696&lt;p&gt;As explained above we are using caching basically for everything. It is the
5697corner stone of our services. At first we were very careful about the quantity
5698of things we stored in &lt;a href=&#34;https://redis.io/&#34;&gt;Redis&lt;/a&gt;. But we later found out that
5699the memory footprint is very low even when storing large amount of data in it.&lt;/p&gt;
5700&lt;p&gt;So we gradually increased our usage to caching whole HTML outputs of dashboard.
5701This improved our performance in order of magnitude. And by using native TTL
5702support this goes hand in hand with our needs.&lt;/p&gt;
5703&lt;p&gt;The reason why we choose &lt;a href=&#34;https://redis.io/&#34;&gt;Redis&lt;/a&gt; over
5704&lt;a href=&#34;https://memcached.org/&#34;&gt;Memcached&lt;/a&gt; was the nature of scalability of Redis out
5705of the box. But all this can be achieved with Memcached.&lt;/p&gt;
5706&lt;h2 id=&#34;conclusion&#34;&gt;Conclusion&lt;/h2&gt;
5707&lt;p&gt;There are a lot more details that could have been written and every single topic
5708in here deserves it&#39;s own post but you probably got the idea about the problems
5709we faced.&lt;/p&gt;
5710</content:encoded>
5711 </item>
5712
5713
5714
5715 <item>
5716 <title>Golang profiling simplified</title>
5717 <link>https://mitjafelicijan.com/golang-profiling-simplified.html</link>
5718 <pubDate>Tue, 07 Mar 2017 12:00:00 &#43;0200</pubDate>
5719 <guid>https://mitjafelicijan.com/golang-profiling-simplified.html</guid>
5720 <description>Many posts have been written regarding profiling in Golang and I haven’t foundproper tutorial regarding this.</description>
5721 <content:encoded>&lt;p&gt;Many posts have been written regarding profiling in Golang and I haven’t found
5722proper tutorial regarding this. Almost all of them are missing some part of
5723important information and it gets pretty frustrating when you have a deadline
5724and are not finding simple distilled solution.&lt;/p&gt;
5725&lt;p&gt;Nevertheless, after searching and experimenting I have found a solution that
5726works for me and probably should also for you.&lt;/p&gt;
5727&lt;h2 id=&#34;where-are-my-pprof-files&#34;&gt;Where are my pprof files?&lt;/h2&gt;
5728&lt;p&gt;By default pprof files are generated in /tmp/ folder. You can override folder
5729where this files are generated programmatically in your golang code as we will
5730see below in example.&lt;/p&gt;
5731&lt;h2 id=&#34;why-is-my-cpu-profile-empty&#34;&gt;Why is my CPU profile empty?&lt;/h2&gt;
5732&lt;p&gt;I have found out that sometimes CPU profile is empty because program was not
5733executing long enough. Programs, that execute too quickly don’t produce pprof
5734file in my cases. Well, file is generated but only contains 4KB of information.&lt;/p&gt;
5735&lt;h2 id=&#34;profiling&#34;&gt;Profiling&lt;/h2&gt;
5736&lt;p&gt;As you can see from examples we are executing dummy_benchmark functions to
5737ensure some sort of execution. Memory profiling can be done without such a
5738“complex” function. But CPU profiling needs it.&lt;/p&gt;
5739&lt;p&gt;Both memory and CPU profiling examples are almost the same. Only parameters in
5740main function when calling profile.Start are different. When we set
5741profile.ProfilePath(“.”) we tell profiler to store pprof files in the same
5742folder as our program.&lt;/p&gt;
5743&lt;h3 id=&#34;memory-profiling&#34;&gt;Memory profiling&lt;/h3&gt;
5744&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;package&lt;/span&gt; main
5745&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5746&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; (
5747&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;fmt&amp;#34;&lt;/span&gt;
5748&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;time&amp;#34;&lt;/span&gt;
5749&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;github.com/pkg/profile&amp;#34;&lt;/span&gt;
5750&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;)
5751&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5752&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;func&lt;/span&gt; dummy_benchmark() {
5753&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5754&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; fmt.Println(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;first set ...&amp;#34;&lt;/span&gt;)
5755&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; i := 0; i &amp;lt; 918231333; i&#43;&#43; {
5756&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; i *= 2
5757&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; i /= 2
5758&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5759&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5760&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;-time.After(time.Second*3)
5761&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5762&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; fmt.Println(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;sencond set ...&amp;#34;&lt;/span&gt;)
5763&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; i := 0; i &amp;lt; 9182312232; i&#43;&#43; {
5764&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; i *= 2
5765&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; i /= 2
5766&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5767&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
5768&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5769&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;func&lt;/span&gt; main() {
5770&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;defer&lt;/span&gt; profile.Start(profile.MemProfile, profile.ProfilePath(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;.&amp;#34;&lt;/span&gt;), profile.NoShutdownHook).Stop()
5771&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; dummy_benchmark()
5772&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
5773&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h3 id=&#34;cpu-profiling&#34;&gt;CPU profiling&lt;/h3&gt;
5774&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;package&lt;/span&gt; main
5775&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5776&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;import&lt;/span&gt; (
5777&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;fmt&amp;#34;&lt;/span&gt;
5778&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;time&amp;#34;&lt;/span&gt;
5779&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;github.com/pkg/profile&amp;#34;&lt;/span&gt;
5780&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;)
5781&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5782&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;func&lt;/span&gt; dummy_benchmark() {
5783&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5784&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; fmt.Println(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;first set ...&amp;#34;&lt;/span&gt;)
5785&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; i := 0; i &amp;lt; 918231333; i&#43;&#43; {
5786&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; i *= 2
5787&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; i /= 2
5788&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5789&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5790&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &amp;lt;-time.After(time.Second*3)
5791&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5792&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; fmt.Println(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;sencond set ...&amp;#34;&lt;/span&gt;)
5793&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;for&lt;/span&gt; i := 0; i &amp;lt; 9182312232; i&#43;&#43; {
5794&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; i *= 2
5795&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; i /= 2
5796&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; }
5797&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
5798&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5799&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#00f&#34;&gt;func&lt;/span&gt; main() {
5800&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; &lt;span style=&#34;color:#00f&#34;&gt;defer&lt;/span&gt; profile.Start(profile.CPUProfile, profile.ProfilePath(&lt;span style=&#34;color:#a31515&#34;&gt;&amp;#34;.&amp;#34;&lt;/span&gt;), profile.NoShutdownHook).Stop()
5801&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt; dummy_benchmark()
5802&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;}
5803&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;h3 id=&#34;generating-profiling-reports&#34;&gt;Generating profiling reports&lt;/h3&gt;
5804&lt;pre tabindex=&#34;0&#34; style=&#34;background-color:#fff;&#34;&gt;&lt;code&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# memory profiling&lt;/span&gt;
5805&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;go build mem.go
5806&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;./mem
5807&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;go tool pprof -pdf ./mem mem.pprof &amp;gt; mem.pdf
5808&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;
5809&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;&lt;span style=&#34;color:#008000&#34;&gt;# cpu profiling&lt;/span&gt;
5810&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;go build cpu.go
5811&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;./cpu
5812&lt;/span&gt;&lt;/span&gt;&lt;span style=&#34;display:flex;&#34;&gt;&lt;span&gt;go tool pprof -pdf ./cpu cpu.pprof &amp;gt; cpu.pdf
5813&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;p&gt;This will generate PDF document with visualized profile.&lt;/p&gt;
5814&lt;ul&gt;
5815&lt;li&gt;&lt;a href=&#34;/posts/go-profiling/golang-profiling-mem.pdf&#34;&gt;Memory PDF profile example&lt;/a&gt;&lt;/li&gt;
5816&lt;li&gt;&lt;a href=&#34;/posts/go-profiling/golang-profiling-cpu.pdf&#34;&gt;CPU PDF profile example&lt;/a&gt;&lt;/li&gt;
5817&lt;/ul&gt;
5818</content:encoded>
5819 </item>
5820
5821
5822
5823 <item>
5824 <title>Software development and my favorite pitfalls</title>
5825 <link>https://mitjafelicijan.com/software-development-pitfalls.html</link>
5826 <pubDate>Tue, 10 Nov 2015 12:00:00 &#43;0200</pubDate>
5827 <guid>https://mitjafelicijan.com/software-development-pitfalls.html</guid>
5828 <description>Over the years I had the privilege to work on some very excited projects both insoftware development field and also in electronics field and every experiencetaught me some invaluable lessons about how NOT TO approach development.</description>
5829 <content:encoded>&lt;p&gt;Over the years I had the privilege to work on some very excited projects both in
5830software development field and also in electronics field and every experience
5831taught me some invaluable lessons about how NOT TO approach development. And
5832through this post I will try to point out some absurd, outdated techniques I
5833find the most annoying and damaging during a development cycle. There will be
5834swearing because this topic really gets on my nerves and I never coherently
5835tried to explain them in writing. So if I get heated up, please bear with me.&lt;/p&gt;
5836&lt;p&gt;As new methods of project management are emerging, underlying processes still
5837stay old and outdated. This is mainly because we as people are unable to
5838completely shift away from these approaches.&lt;/p&gt;
5839&lt;p&gt;I was always struggling with communication, and many times that cost me a
5840relationship or two because I was not on the ball all the time. Through every
5841experience, I became more convinced that I am the problem and never ever doubted
5842that the problem may be that communication never evolved a single step from
5843emails. And if you think for a second, not many things have changed around this
5844topic. We just have different representations of email (message boards, chats,
5845project management tools). And I believe this is the real issue we are facing
5846now.&lt;/p&gt;
5847&lt;p&gt;There are many articles written about hyper connectivity and the effects that
5848are a direct result of it. But mainstream does nothing towards it. We are just
5849putting out fires, and we do nothing to prevent it. I am certain this will be a
5850major source of grief in coming years. And what we all can do to avoid this is
5851to change our mindset and experiment on our communication skills, development
5852approaches. We need to maximize possible output that a person can give. And to
5853achieve this we need to listen to them, encourage them. I know that not
5854everybody is a naturally born leader, but with enough practice and encouragement
5855they also can become active participants in leadership.&lt;/p&gt;
5856&lt;p&gt;There are many talks now about methodologies such as Scrum, Kanban, Cleanroom
5857and they all fucking piss me of :). These are all boxes that imprison people and
5858take away their freedom of thought. This is a straightforward mindfuck /
5859amputation of creativity.&lt;/p&gt;
5860&lt;p&gt;Let me list a couple of things that I find really destructive and bad for a
5861project and in a long run company.&lt;/p&gt;
5862&lt;h2 id=&#34;ping-emails&#34;&gt;Ping emails&lt;/h2&gt;
5863&lt;p&gt;Ping emails are emails you have to write as soon as you receive an email. Its
5864sole purpose is to inform the sender that you received their email, and you are
5865working on it. Its result is only to calm down the sender that their task is
5866being dealt with. It’s intent basically is, I did my job by sending you this
5867email, so I am on clear grounds. I categorize this email as fuck you email.
5868This is one of the most irritating types of emails I need to write. This is the
5869ultimate control freak show you can experience, and it gives the sender a false
5870feeling of control. Newsflash: We do not live in 1982 where there was a
5871possibility that email never reached the destination. I really hate this from
5872the bottom of my heart.&lt;/p&gt;
5873&lt;p&gt;They should be like: “Yes, I am fucking alive, and I am at your service my
5874leash!”. I guess if I would reply like this, I wouldn’t have to write any more
5875of this kind of messages.&lt;/p&gt;
5876&lt;h2 id=&#34;everybody-is-a-project-manager&#34;&gt;Everybody is a project manager&lt;/h2&gt;
5877&lt;p&gt;Well, this is a tough one. I noticed that as soon as you let people to give
5878their suggestions, you are basically screwed. There is a truth in the saying:
5879“Give low expectations and deliver little more than you promised.”.&lt;/p&gt;
5880&lt;p&gt;People tend to take a role of a manager as soon as they are presented with an
5881opportunity. And by getting angry at them, you only provoke yourself. They are
5882not at fault. You just need to tell them they are only giving suggestions and
5883not tasks at the beginning and everything will be alright. But if you give them
5884a feeling that they are in control, you will have immense problems explaining
5885why their features are not in current release.&lt;/p&gt;
5886&lt;p&gt;Project mission must be always leading project requirements and any deviation
5887from it will result in major project butchering. And by this, I mean that the
5888project will get its own path, and you will be left with half done software that
5889helps nobody. Clear mission goals and clean execution will allow you to develop
5890software will clear intent.&lt;/p&gt;
5891&lt;h2 id=&#34;we-are-never-wrong&#34;&gt;We are never wrong&lt;/h2&gt;
5892&lt;p&gt;I find this type of arrogance the worst. We must always conduct ourselves that
5893we are infallible and cannot make mistakes. As soon as a procedure or process is
5894established, there is no room for changes or improvements. This is the most
5895idiotic thing someone can say of think. I think that processes need to involve
5896and change over time. This is imperative and need to have in your organization
5897if you want to improve and develop company. We all need to grow balls and change
5898everything in order to adapt to current situations. Being a prisoner of
5899predefined processes kills creativity.&lt;/p&gt;
5900&lt;p&gt;I am constantly trying new software for project managing and communication. I
5901believe every team has its own dynamic, and it needs to be discovered
5902organically and naturally through many experiments. By putting the team in a
5903box, you are amputating their creativity and therefore minimizing their
5904potential. But if you talk to an executive, you will mainly find archetypical
5905thinking and a strong need to compartmentalize everything from business
5906processes to resource management. And this type of management that often
5907displays micromanagement techniques only works for short periods (couple of
5908years) and then employees either leave the company or become basically retarded
5909drones on autopilot.&lt;/p&gt;
5910&lt;h2 id=&#34;micromanaging&#34;&gt;Micromanaging&lt;/h2&gt;
5911&lt;p&gt;This basically implies that everybody on the team is an idiot who needs to have
5912a to-do list that they cannot write themselves. How about spoon-feeding the team
5913at launch because besides the team leader, everybody must be a retarded idiot at
5914best?&lt;/p&gt;
5915&lt;p&gt;I prefer milestones as they give developers much more freedom and creativity in
5916developing and not waste their time checking some bizarre to-do list that was
5917not even thought through. Projects constantly change throughout the development
5918cycle, and all you are left at the end is a list of unchecked tasks and the
5919wrath of management why they are not completed. Best WTF moment!&lt;/p&gt;
5920&lt;h2 id=&#34;human-contact--no-need-for-it&#34;&gt;Human contact — no need for it!&lt;/h2&gt;
5921&lt;p&gt;We are vigorously trying to eliminate physical contact by replacing short
5922meetings with software, with no regards that we are not machines. Many times a
5923simple 5-min meeting at morning can solve most of the problems. In rapid
5924development, short bursts of man to man communication is possibly the best way
5925to go.&lt;/p&gt;
5926&lt;p&gt;We now have all this software available, and all what we get out of it is a
5927giant clusterfuck. An obstacle and not a solution. So, why we still use them?&lt;/p&gt;
5928&lt;h2 id=&#34;mvp-is-killing-innovation&#34;&gt;MVP is killing innovation&lt;/h2&gt;
5929&lt;p&gt;Many will disagree with me on this one, but I stand strong by this statement.
5930What I noticed in my experience that all this buzz words around us only mislead
5931and capture us in a circle of solving issues that already have a solution, but
5932we are unable to see it without using some fancy word for it.&lt;/p&gt;
5933&lt;p&gt;The toughest thing to do for a developer is to minimize requirements. Well, this
5934is though only for bad developers. Yes, I said it. There are many types of
5935developers out there. And those unable to minimize feature scope are the ones
5936you don’t need on your team. Their only goal is to solve problems that exist
5937only in their heads. And then you have to argue with them, and waste energy on
5938them, instead of developing your awesome product. They are a cancer and I
5939suggest you cut them off.&lt;/p&gt;
5940&lt;p&gt;MVP as an idea is great, but sadly people don’t understand underlying
5941philosophy, and they spent too much time focusing and fixating on something that
5942every sane person with normal IQ will understand without some made up
5943acronym. And the result is a lot of talking and barely no execution.&lt;/p&gt;
5944&lt;p&gt;Well, MVP is not directly killing innovation, but stupid people do when they try
5945to understand it.&lt;/p&gt;
5946&lt;h2 id=&#34;pressure-wasteland&#34;&gt;Pressure wasteland&lt;/h2&gt;
5947&lt;p&gt;You must never allow to be pressured into confirming a deadline if you are not
5948confident. We often feel a need that we are in service of others, which is true
5949to some extent. But it is also true that others are in service to us to some
5950extent. And we forget this all the time. We are all pressured all the time to
5951make decisions just to calm other people down. And when they leave your office
5952you experience WTF moment :) How the hell did they manage to fuck me up again?&lt;/p&gt;
5953&lt;p&gt;People need to realize that the more pressure you put on somebody, the less they
5954will be able to do. So 5-min update email requests will only resolve in mental
5955breakdown and inability to work that day. Constant poking is probably the only
5956thing I lose my mind instantly. For all you that are doing this: “Stop bothering
5957us with your insecurities and let us do our job. We will do it quicker and
5958better without you breathing down our necks.”&lt;/p&gt;
5959&lt;p&gt;If this happens to me, I end up with no energy at the end. Don’t you get it?
5960You will get much more from and out of me if you ask me like a human person and
5961not your personal butler. On a long run, you are destroying your relationships
5962and nobody would want to work with you. Your schizophrenic approach will damage
5963only you in a long run. Nobody is anybody’s property.&lt;/p&gt;
5964&lt;h2 id=&#34;conclusion&#34;&gt;Conclusion&lt;/h2&gt;
5965&lt;p&gt;I am guilty of many things described in this post. And I find it hard sometimes
5966to acknowledge this. And I lie to myself and try vigorously to find some
5967explanation why I do these things. There is always space for growth. And maybe
5968you will also find some of yourself in this post and realize what needs to
5969change for you to evolve.&lt;/p&gt;
5970</content:encoded>
5971 </item>
5972
5973
5974
5975 <item>
5976 <title>Wireless sensor networks</title>
5977 <link>https://mitjafelicijan.com/wireless-sensor-networks.html</link>
5978 <pubDate>Thu, 24 Oct 2013 12:00:00 &#43;0200</pubDate>
5979 <guid>https://mitjafelicijan.com/wireless-sensor-networks.html</guid>
5980 <description>Zigbee networks have this wonderful capability to self-heal, which means theycan reorder connections between them if one of them is inoperable.</description>
5981 <content:encoded>&lt;p&gt;Zigbee networks have this wonderful capability to self-heal, which means they
5982can reorder connections between them if one of them is inoperable. This works
5983our of the box when you deploy them. But you have to have in mind that achieving
5984this is not as easy as you would think. None of it is plug&amp;amp;play. So to make
5985your life a bit easier, here are some pointers which, I hope, will help you.&lt;/p&gt;
5986&lt;ul&gt;
5987&lt;li&gt;Be careful when you are ordering your equipment abroad. There are many rules
5988and regulations you need to comply before you get your Xbee radios. What they
5989do is they wait until you prove that you won’t use the technology for some
5990kind of evil take over control of the world project :). For this, they have
5991EAR (Export Administration Regulations) which basically means “This product
5992may require a license to export from the United States.”.&lt;/li&gt;
5993&lt;li&gt;I don’t know if this applies for every country, but when we purchased our Xbee
5994radios from Mouser, this was mandatory! What we needed to do was to print out
5995a form and write information about our company and send them a copy via
5996email. With this document, we proved that we are a legitimate company.&lt;/li&gt;
5997&lt;li&gt;When you complete your purchase and send all the documentation, you are not
5998clear yet. Then customs will take it from there :). There will be some
5999additional costs. Before purchasing, make sure you have as much information
6000about costs as possible. Because it can get costly in the end.&lt;/li&gt;
6001&lt;li&gt;I suggest you use companies from your country. You can seriously cut your
6002costs. Here in Slovenia, the best option so far as I know is Farnell. And
6003based on my personal experience, they rock! All I need to say!&lt;/li&gt;
6004&lt;li&gt;Make plans when ordering larger quantities. Do not, I say, do not make your
6005orders in December! :) Believe me! You will have problems with stock they can
6006provide for you. So, we were forced to buy some things from Mouser, which was
6007extremely painful because of all the regulations you need to obey when
6008importing goods from the USA.&lt;/li&gt;
6009&lt;li&gt;Make sure that firmware version on your Xbee radios is exactly the same! Do
6010not get creative!!! I propose using templates. You can get template by
6011exporting settings/profile in X-CTU application. Make sure you have enabled
6012“Upgrade firmware” so you can be sure each radio has the same firmware.&lt;/li&gt;
6013&lt;li&gt;And again: make plans! Plan everything! In months advanced! You will thank me
6014later :)&lt;/li&gt;
6015&lt;li&gt;Test, test, test. Wireless networks can be tricky.&lt;/li&gt;
6016&lt;/ul&gt;
6017&lt;p&gt;If you are serious, I suggest you buy this book, Building Wireless Sensor
6018Networks. You will get a glimpse of how networks work in lumens terms. It is a
6019good starting point for everybody who wants to build wireless networks.&lt;/p&gt;
6020&lt;p&gt;&lt;strong&gt;Additional resources:&lt;/strong&gt;&lt;/p&gt;
6021&lt;ul&gt;
6022&lt;li&gt;&lt;a href=&#34;http://www.digi.com/aboutus/export/generalexportinfo&#34;&gt;http://www.digi.com/aboutus/export/generalexportinfo&lt;/a&gt;&lt;/li&gt;
6023&lt;li&gt;&lt;a href=&#34;http://doresearch.stanford.edu/research-scholarship/export-controls/export-controlled-or-embargoed-countries-entities-and-persons&#34;&gt;http://doresearch.stanford.edu/research-scholarship/export-controls/export-controlled-or-embargoed-countries-entities-and-persons&lt;/a&gt;&lt;/li&gt;
6024&lt;li&gt;&lt;a href=&#34;http://www.bis.doc.gov/licensing/exportingbasics.htm&#34;&gt;http://www.bis.doc.gov/licensing/exportingbasics.htm&lt;/a&gt;&lt;/li&gt;
6025&lt;/ul&gt;
6026</content:encoded>
6027 </item>
6028
6029
6030
6031 <item>
6032 <title>LED technology might not be as eco-friendly as you think</title>
6033 <link>https://mitjafelicijan.com/led-technology-not-so-eco.html</link>
6034 <pubDate>Fri, 09 Mar 2012 12:00:00 &#43;0200</pubDate>
6035 <guid>https://mitjafelicijan.com/led-technology-not-so-eco.html</guid>
6036 <description>There is a lot of talk about LED technology.</description>
6037 <content:encoded>&lt;p&gt;There is a lot of talk about LED technology. It is beginning to infiltrate
6038industry at a fast rate, and it’s a challenge for designers and also engineers.
6039I wondered when a weakness will be revealed. Then I stomped on an article
6040talking about harm in using LED technology. It looks like this magical
6041technology is not so magical and eco-friendly.&lt;/p&gt;
6042&lt;p&gt;A new study from the University of California indicates that LED lights contain
6043toxic metals, and should be produced, used and disposed of carefully. Besides
6044the lead and nickel, the bulbs and their associated parts were also found to
6045contain arsenic, copper, and other metals that have been linked to different
6046cancers, neurological damage, kidney disease, hypertension, skin rashes and
6047other illnesses in humans, and to ecological damage in waterways.&lt;/p&gt;
6048&lt;p&gt;Since then, I haven’t yet found any regulation for disposal of LED lights or any
6049other regulation or standard. This might be a problem in the future. And it is a
6050massive drawback. This might have quite an impact on consumer market.&lt;/p&gt;
6051&lt;p&gt;Nevertheless, there is a potential, and I am sure the market will adapt. I also
6052hope I will be reading documents regarding solution for this concern soon.&lt;/p&gt;
6053&lt;p&gt;&lt;strong&gt;Additional resources:&lt;/strong&gt;&lt;/p&gt;
6054&lt;ul&gt;
6055&lt;li&gt;&lt;a href=&#34;http://ezinearticles.com/?Recycling-and-Disposal-of-Light-Bulbs&amp;amp;id=1091304&#34;&gt;Recycling and Disposal of Light Bulbs&lt;/a&gt;&lt;/li&gt;
6056&lt;li&gt;&lt;a href=&#34;http://www.ehow.com/how_7483442_dispose-lowenergy-light-bulb.html&#34;&gt;How to Dispose of a Low-Energy Light Bulb&lt;/a&gt;&lt;/li&gt;
6057&lt;/ul&gt;
6058</content:encoded>
6059 </item>
6060
6061
6062
6063 <item>
6064 <title>Most likely to succeed in the year of 2011</title>
6065 <link>https://mitjafelicijan.com/most-likely-to-succeed-in-year-of-2011.html</link>
6066 <pubDate>Thu, 13 Jan 2011 12:00:00 &#43;0200</pubDate>
6067 <guid>https://mitjafelicijan.com/most-likely-to-succeed-in-year-of-2011.html</guid>
6068 <description>The year of 2010 was definitely the year of Geo-location.</description>
6069 <content:encoded>&lt;p&gt;The year of 2010 was definitely the year of Geo-location. The market responded
6070beautifully and lots of very cool services were launched. We all have to thank
6071the mobile market for such extensive adoption. With new generations of mobile
6072phones that are not only buffed with high-tech hardware but are also affordable.
6073We can now manage tasks that were not so long time ago, almost Star Trek’ish.
6074And all this had and has great influence on the destination to which we are
6075going now.&lt;/p&gt;
6076&lt;p&gt;Reading all this articles about new innovation about new thriving technologies
6077makes me wonder what’s the next step. The future is the mesh, like Lisa Gansky
6078said in her book The Mesh.&lt;/p&gt;
6079&lt;p&gt;Many still have conservative views on distributed systems. The problems with
6080security of information. Fear of not controlling every aspect of information
6081flow. I am very opened to distributed systems and heterogeneous applications,
6082and I think this is the correct and best way to proceed.&lt;/p&gt;
6083&lt;p&gt;This year will definitely be about communication platforms. Mobile to mobile.
6084Machine to mobile and vice versa. All the tech is available and ready to put
6085into action. Wireless is today’s new mantra. And the concept of semantic web is
6086now ready for industry.&lt;/p&gt;
6087&lt;p&gt;Applications and developers now can gain access to new layers of systems and can
6088prepare and build solutions to meet the high quality needs of market. The speed
6089is everything now.&lt;/p&gt;
6090&lt;p&gt;My vote goes to “Machine to Machine” and “Embedded Systems”!&lt;/p&gt;
6091&lt;ul&gt;
6092&lt;li&gt;&lt;a href=&#34;http://en.wikipedia.org/wiki/Machine-to-Machine&#34;&gt;Machine-to-Machine&lt;/a&gt;&lt;/li&gt;
6093&lt;li&gt;&lt;a href=&#34;http://www.bitxml.org/&#34;&gt;The ultimate M2M communication protocol&lt;/a&gt;&lt;/li&gt;
6094&lt;li&gt;&lt;a href=&#34;http://www.coosproject.org/maven-site/1.0.0/project-info.html&#34;&gt;COOS Project (connectivity initiative)&lt;/a&gt;&lt;/li&gt;
6095&lt;li&gt;&lt;a href=&#34;http://m2m.com/index.jspa&#34;&gt;Community for machine-to-machine&lt;/a&gt;&lt;/li&gt;
6096&lt;li&gt;&lt;a href=&#34;http://en.wikipedia.org/wiki/Embedded_system&#34;&gt;Embedded system&lt;/a&gt;&lt;/li&gt;
6097&lt;/ul&gt;
6098</content:encoded>
6099 </item>
6100
6101
6102 </channel>
6103</rss>
generated by cgit v1.2.3 (git 2.46.0) at 2026-04-30 21:45:28 +0000