How to trigger a pipeline when a submodule changes?

Question

I have a few repositories that use the same submodule. Is there a way to set those repositories to run a pipeline automatically when the origin of their submodule changes?

For instance if I push something on the parent repo, I want it to automatically notify the change to all the repositories using it as a submodule that the change has happened and that their pipeline needs to be run.

Answer 1

There is a feature called multi-project pipeline in GitLab that can trigger builds between repositories, but only in the Premium and Silver version:

https://docs.gitlab.com/ee/ci/multi_project_pipelines.html

You could get something to work with this. You just need to remember that just because you push new changes to your submodule, the repositories that use this submodule are not updated. They are still on the same commit as before.

You can of course do anything you want if you really want to. If you have a server where you can set up a gitlab runner, you can do something like this:

• Create a new GitLab user, RoboGit, with access to the submodule and repositories that use that submodule
• Install and register a gitlab runner on the server
• Create a job for the submodule

This job can then manually check out your dependent projects, find the submodule, update them to the newest version, and then commit these changes. The author of these changes would then be RoboGit, and these changes would trigger build jobs in these repositories. You would get something like what you described in your question.