From b5a074406d33159b17eac5dc19f03ef2ea8e0fd3 Mon Sep 17 00:00:00 2001 From: Mitja Felicijan Date: Wed, 31 May 2023 12:32:48 +0200 Subject: Blog: Errand project --- ...nting-task-runner-that-i-actually-used-daily.md | 112 +++++++++++++++++++++ 1 file changed, 112 insertions(+) create mode 100644 content/posts/2023-05-31-re-inventing-task-runner-that-i-actually-used-daily.md (limited to 'content') diff --git a/content/posts/2023-05-31-re-inventing-task-runner-that-i-actually-used-daily.md b/content/posts/2023-05-31-re-inventing-task-runner-that-i-actually-used-daily.md new file mode 100644 index 0000000..f2c19fa --- /dev/null +++ b/content/posts/2023-05-31-re-inventing-task-runner-that-i-actually-used-daily.md @@ -0,0 +1,112 @@ +--- +title: "Re Inventing Task Runner That I Actually Used Daily" +url: re-inventing-task-runner-that-i-actually-used-daily.html +date: 2023-05-31T12:21:10+02:00 +draft: false +--- + +Couple of months ago I had this brilliant idea of re-inventing the wheel by making an alternative for make. And so I went. Boldly into the battle. And to my big surprise my attempt resulted in not a completely useless piece of software. + +My initial requirements were quite simple but soon grow into something more ambitious. And looking back I should have stuck to the simple version. My laziness was on my side this time though. Because I haven’t implemented some of the features I now realise I really didn’t need them and they would bog the whole program and make it be something it was never meant to be. + +My basic requirements were following: + +- Syntax should be a tiny bit inspired by Rake and Rakefiles. +- Should borrow the overall feel of a unit test experience. +- Using something like Python would be a bit of an overkill. +- The program must be statically compiled, so it can run on same architecture without libc, musl dependencies or things like that. +- Install ruby for rake is a bit overkill and can not be done with certain really lightweight distributions like Alpine Linux. This tool would be usable on such lightweight systems for remote debugging. +- I want to use it for more than just compiling things. I want to use it as an entry-point into a project, and I want this to help me indirectly document the project as well. +- It should be an abstraction over bash shell or the default system shell. + - Each task essentially becomes its own shell instance. +- Must work on Linux and macOS systems. +- By default, running `erd` list all the available tasks (when I use make, I usually put a disclaimer that you should check Makefile to see all available target). +- Should support passing arguments when you run it from a shell. +- Normal variable as the same as environmental variables. There is no distinction. Every variable is also essentially an environment variable and can be used by other programs. +- State between tasks is not shared, and this makes this “pure” shell instances. +- Should be single-threaded for the start and later expanded with `@spawn` command. +- Variables behave like macros and are preprocessed before evaluation. +- Should support something like `assure` that would check if programs like C compiler or Python (whatever the project requires) are installed on a machine. + +Quite a reasonable list of requirements. I do this things already in my Makefiles or/and Bash scripts. But I would like to avoid repeating myself every time I start working on something new. + +So I started with the following syntax. + +```ruby +@env on + +# Override the default shell. +@shell /bin/bash + +# Assure that program is installed. +@assure docker-compose pip python3 + +# Load local dotenv files (these are then globally available). +@dotenv .env +@dotenv .env.sample +@dotenv some_other_file + +# This are local variables but still accessible in tasks. +@var HI = "hey" +@var TOKEN = "sometoken" +@var EMAIL = "m@m.com" +@var PASSWORD = "pass" +@var EDITOR = "vim" + +@task dev "Test chars .:'}{]!//" does + echo "..." $HI +end + +@task clean "Cleans the obj files" does + rm .obj +end + +@task greet "Greets the user" does + echo "Hi user $TOKEN or $WINDOWID $EMAIL" +end + +@task stack "Starts Docker stack" does + docker-compose -f stack.yml up +end + +@task todo "Shows all todos in source files and count them" does + grep -ir "TODO|FIXME" . | wc -l +end + +@task test1 "For testing 1" does + unknown-command + echo "test1" + ls -lha +end + +@task test2 "For testing 2" does + echo "test1" + ls -lha + docker-compose -f samples/stack.yml up +end +``` + +One thing that I really like about Errand. Yes, this is what it is called. And it is available at https://git.mitjafelicijan.com/errand.git/about/. Moving on. One thing that I really like is that a task is a persistent shell. By that I mean, that the whole task, even if it contains multiple command in one shell. In make each line in a target is that and you need to combine lines or add `\` at the end of the line. + +```bash +# How you do this things in make. +target: + source .venv/bin/activate \ + python script.py +``` + +This solves this problem. Consider each task and what is being executed in that task a shell that will only close when all the tasks are completed. + +By self-documenting I mean that if you are in a directory with `Errandfile` in, if you only type `erd` and press enter it should by default display all the possible targets. In make i was doing this by having a first target be something like `default` that echos the message “Check Makefile for all available target.” Because all of the tasks in Errand require a message I use that to display let’s call it table of contents. + +Because I don’t use any external dependencies this whole thing can be statically compiled. So that also checked one of the boxes. + +It works on Linux and on a Mac so that’s also a bonus. I don’t believe this would work on Windows machines because of the way that I use shell instances. By you could use something like Windows Subsystem for Linux and run it in there. That is a valid option. + +To finish this essay off, how was it to use it in “real life”. I have to be honest. Some of the missing features still bother me. `@dotenv` directive is still missing and I need to implement this ASAP. + +Another thing that needs to happen is support for streaming output. Currently commands like `docker-compose` that runs in foreground mode is not compatible with Errand. So commands that stream output are an issue. I need to revisit how I initiate shell and how I read stdout and stderr. But that shouldn’t be a problem. + +I have been very satisfied with this thing. I am pleasantly surprised by how useful it is. I really wanted to test this in the wild before I commit to it. I have more abandoned project than Google and it’s bringing a massive shame to my family at this point. So I wanted to be sure that this is even useful. And it actually is. Quite surprised at myself. + +I really need to package this now and write proper docs. And maybe rewrite tokeniser. Its atrocious right now. Site to behold! But that is an issue for another time. -- cgit v1.2.3