gemspecs created by bundle gem won't build in Tebako images without access to the host git repo.

[bradgessler]

Continuing from issue tamatebako/tebako#233 where I discovered this issue.

When gems are created via bundle gem, the spec.files are pulled from a list of files created by git. When this is mounted inside of an image and built, the path git expects is from the host machine, not the container, so it fails silently and no files are returned to the gemspec.

Tebako then picks up the valid gemspec with no files and builds it, but nothing is in there, which creates surprisingly results when the tebako build fails.

[bradgessler]

I created a PR at #41; however I think it's brittle. It only works assuming the host directory that's mounted into the container also has a git repe. If it doesn't, tebako may fail in this surprising way.

Another mitigation this problem might include Tebako doing a few sanity checks on the files its packaging. For example, if tebako detects there's no files its packaging, it could fail with a more helpful error message.

[maxirmx]

I guess the issue is that you checkout the repository with gem source using host installation of git ("host repo") and run tebako press that calls container installation of git.

Package using an ephemeral container shall work for "host repo"

At least it works for our CI tests for fontist gem that uses magic bundler definition

[bradgessler]

I guess the issue is that you checkout the repository with gem source using host installation of git ("host repo") and run tebako press that calls container installation of git.

Correct, that's why this line in my PR has been added to the container: https://github.com/tamatebako/tebako-ci-containers/pull/41/files#diff-c3917ed6015b41275b16f95b557fffa7ed17fd34b4f6205a5c6b1855996a465bR46-R49