CLI-1404: Artifact: .gitignore file parsing issues

[regilero]

Hello, I'm coming to acli after the BLT EOL (acquia/blt#4736).
We used BLT for artifact generation for ACSF and are trying to use acli for the same task.

BLT had several tools to manage the final files present in the artifact, some of them common with acli (like the sanitize steps).
But the main exclusion stuff was done via a specific deploy-exclude.txt list (and even hooks), and then a specific .gitignore file put in the final artifact (so not the same .gitignore file than the one used to manage the project.

Here acli is using the project main .gitignore file (and only this one) to perform the first copy of files and directories into the temporary working folder. Without any way to add a specific .gitignore for the final artifact.
So it seems everything which is not handled by the sanitize tasks have to be excluded in this main .gitignore file (and we are trying to merge the blt files in this .gitignore).

Using this first exclusion of files before making the copy seems to work, as most project would exclude in this file the Drupal core files and all the work linked to composer. And acli would run composer in the temp directory to regenerate the missing files. This is documented as a "speed up" in the code. But I think it is also a way of excluding files from the artifact.

Our project contains folders that we want to track in git, but that we do not want in the final artifact (you can think of tests for example, or front related stuff). Not a problem, we can generate a .gitignore file just before the artifact generation, to fit the real exclusion list. Here a --ignore-dirty like in BLT would be helpful as the fact that acli wants to get a clean git status before artifact generation is a minor problem, but that's another subject.

Problem

The problem is that in acli the parsing of this .gitignore is done via Symfony Finder ignoreVCS() function, and this function is quite bad at parsing the .gitignore file.

• it is only scanning one .gitignore file, ignoring all .gitignore files present in subdirectories or parent directories
• it does not respect strictly the same syntax as git, so some git silent errors or 'strange' parsing would not be treated the same way in the finder, and some invalid git syntax are valid for the Finder. I made an issue on the finder for that Finder: ignoreVCSIgnored() remove or document deviations with VCS results  symfony/symfony#58175

A simple rule like this one would fail in the finder:

/docroot/*
!/docroot/themes/custom

But this one would work for the finder:

/docroot/*
!/docroot/themes/custom/*

While being wrong for git (the leading /* in the exception is wrong)

I also reported issues with symlinks which may be directly related to this ignoreVCS() function in #1799.

It is quite simple to detect a syntax problem in a .gitignore file while using git, as you can see quite fast which file are tracked or not.

Finding a .gitignore syntax which would be compatible for both the Symfony Finder and git is really harder. And it takes a quuite long time to generate artifacts. Currently I'm still trying to find why I'm lacking some css and js files in my artifact and why I still have a node_modules/ folder with 3 js files in it while having a clear node_modules line in my .gitignore file.

It is currently very hard to produce an artifact of the same quality than blt artifacts.

solutions ?

I would not be surprised by a removal of ignoreVCS() function in the Finder some day. I would be very surprised in this function could one day parse the .gitignore file with the exact same behaviour than the latest git version.
So I think trying to only use the Finder while making the first copy of files will always be a problem.
Or at least the ignoreVCS() part.
One solution would be to add a deploy-exclude.txt file, with specific exclusion rules, and a syntax only valid for acli ... but that's a new file, and it breaks compatibility for people who only relies on the .gitignore file currently.

acli is expecting a working git directory as the starting point of the artifact generation, so another solution would be to use git to get a very precise file list.

This command for example:

git ls-files --cached --others --exclude-standard

Using this you get a very precise list of files that git is managing, based on the .gitignore rule (and maybe also based on the forced commit, and on files which were added before changes on the .gitignore files, not sure for these cases). using this would be a more clear reason of not supporting the --ignore-dirty mode as now the current git statut would become really important for the artifact.

This solution would lack an easy way of excluding files while still tracking them on git (like the current one), but at least we could be sure that a file not tracked by git would never be present in the artifact (with the exception of files generated after that by composer install).