Simple CI (Continous Integration)

Jenkins, Travis, GitHub Actions, GitLab CI. The list goes on. There are many CI systems. All of them overcomplicate an extremely simple use case: "I want to trigger custom scripts (usually just a list of simple shell commands) on a server. Either automatically, or manually. And then I want to be follow and see any errors that may happen."

There's no need to invent the wheel 10 different times. Most of the actions required by the CI use case can be handled with most UNIX tools such as tail, cat, inotify etc. At the core of CI must be a triggering system that can be dynamically configured to run a pipeline script.

This program provides that simple triggering system where you simply touch a file, and the associated pipeline will then be executed. You can then follow the log via tail.

The operation of sci is configured through a pipelines.conf configuration file (see sci(7) for configuration language details) and each pipeline will have an associated pipeline trigger file that can be By default, pipeline triggers are placed in /tmp/sci but this can be overridden with the -T flag (WIP feature). For more commandline options see the manpage sci(1) or use the --help option.

Dependencies

Just GNU/Linux! sci is just using the POSIX api, so it should work with *NIX, but it has only been tested on GNU/Linux systems. NOTE: Not tested with muslc systems yet, sci use some libc GNU extensions, but it would be nice to support alpine linux some time in the future.

Build

Build the project using make:

make

Install

Install the project:

make
sudo make install

By default, sci is installed to /usr/local but this can be overridden by providing the PREFIX var:

make
sudo make install PREFIX=/some/path

Package

sci can be packaged for multiple distributions:

Arch Linux

It is recommended that you use an arch linux distribution when building.

Debian

It is recommended that you use the deb-builder.dockerfile docker image to build the debian image.

Building the debian builer docker image

docker build -t debbuilder deb-builder.dockerfile .

Brainstorm

If you dont want to congest your CI server. Too bad. Write faster ci suites. (TODO: implement runners)

I would like to try to avoid writing a million REST APIs, as that just results in bloat usually.

Could this also be used as a systest replacement? The value of systest is the drivers and the configuration files. Not really the controllers themselves. But yes, this system could replace the systest runner scripts. But not the drivers or the configuration files themselves...

Why trigger files instead of IPC (Inter Process Communication)? It was easier to implement. If you know how to add POSIX IPC (not a fan of System-V IPC), please submit a PR :-)

Using

/etc/sci/conf.d/pipelines.conf

aaltitoad-release   https://github.com/sillydan1/aaltitoad      onpush-main         /home/sci/pipelines/cpp-dev-git.sh
aaltitoad-develop   https://github.com/sillydan1/aaltitoad      onpush-dev          /home/sci/pipelines/cpp-rel-git.sh
schoolnotes         https://gitlab.com/sillydan/schoolnotes     manual-name         "echo hello"
horse               https://gtz.dk/horse"                       manual-name         "curl -X POST https://example.com"
cool-horse          https://gtz.dk/horse"                       manual-name         "docker run --rm -v $SCI_PIPELINE_DIR:$SCI_PIPELINE_DIR -v /home/sci/pipelines:/pipelines alpine /pipelines/your-script.sh"
rad-horse           https://gtz.dk/horse"                       manual-name         "/home/sci/pipelines/dockerized-horse.sh"
<name>              <url>                                       <trigger-filename>  <pipeline-command>

Triggers are just bare files that reside in /etc/sci/triggers/ - this means that multiple pipelines can use the same trigger. When a trigger file is being written to or touched, this triggers the associated pipeline. Trigger files are automatically created by the scid daemon during startup or reconfiguring.

Any webhooks should be managed by shim-APIs / adapter APIs that are very slim (possibly flask) REST APIs that just listen for webhook event triggers and does a simple touch <associated file>. It could even read the same configuration file as scid uses to autogenerate these webhooks. But it is explicity NOT part of the core system, as that would be unneeded bloat.

How do I get information about a running pipeline? Perhaps a /var/tmp/sci/<pipeline-name> is continually updated with runtime information? Then you can cat, or tail -f it to get the information.

scid manages running subprocesses, so it must be implemented in a language that handles that nicely.

Pipelines - Should pipelines have a custom language? NO! God already gave us shell scripts! Why would we reinvent the wheel? Take a page out of Jenkins' book. scid should just call some command on trigger. That command could / should usually be a quick shell script (these calls are executed in the dispatched separate thread, so dont worry about sleeping or whatever you need to do). These scripts are equivalent to the Jenkins pipelines, and should update their current state in /var/tmp/scid/$PIPELINE_NAME by simply writing to the file (when implementing runners, we probably need to rsync these files automagically). Oh, and dont worry about cleaning up. Each pipeline execution will be placed in a /tmp/<pipeline-name>-<uuid>/ directory and will be executed by a gimped user. If you need to interact with the linux stuff and it might break other pipelines or whatever, then your pipeline-command should just start a docker container, volume mount the tmpdir and what else you need and run your command in that.

Need multistep pipelines? Then write a multistep shell script! You're the boss of your own CI server man.

#!/bin/bash
# cpp-dev-git-pipeline,sh
# NOTE: Will be executed from /tmp/$SCI_PIPELINE_NAME-<uuid>/
git clone -b dev "$SCI_PIPELINE_URL" "$SCI_PIPELINE_NAME"
echo "clone success" > "/var/tmp/sci/$SCI_PIPELINE_NAME" # You can have any kind of data in the pipeline status file.
cd "$SCI_PIPELINE_NAME"
cmake -B build
cmake --build build

Secrets

Not planned yet. But they could be as simple as a keystore.

Development

What language should I implement scid in?

• c slow devtime, decent tooling, very minimal and forces you to be minimal also. Maybe
• c++ slow devtime, good tooling, very familiar. Can easily get out of hand. Maybe
• python quick, easy, slow performance, terrible multiprocessing capabilities. Maybe
• java slow devtime, bloated. No.
• rust slow devtime (not familiar), great tooling, too many risks for a first prototype. No.
• shell quick, easy, instant spaghetti. No.

I choose c!

I also choose Makefiles! - Just to force myself to use another build system than CMake! If you want compile_commands.json files, you should use bear as it works well