Oh, that's really cool. I was trying to solve this from a different perspective a while ago: I wanted to add some pre-processing that would take a "normal" shell script and render it to the `script` part of the corresponding job at build time, the advantage being that you still have everything self-contained in the gitlab-ci job.

I stopped working on it because dealing with shell shenanigans in the GitLab CI runner environment is such a miserable experience that we're in the process of moving all our jobs to python scripts.