yesolutions/mirror-action

benefits of this over `git clone --bare` and `git push --mirror`?

Closed this issue · 2 comments

jcbhmr commented

Hello! 👋

I'm interested in hosting some internal Git mirrors on GitHub for some SourceForge Git repositories. I was hunting around on the GitHub Actions marketplace and found this GitHub Action. I also Googled some and found that the "recommended" way to mirror a Git repository by GitHub is this:

git clone --bare https://git.code.sf.net/p/mingw/regex .
git push --mirror https://github.com/octocat/mingw-regex.git

where https://github.com/octocat/mingw-regex.git can have a https://username:password@github.com/... auth URL part where username is anything (even just x) and password is a GitHub Personal Access Token. https://stackoverflow.com/questions/18935539/authenticate-with-github-using-a-token

Is there an advantage to using this GitHub Action over something like this? Am I missing something?

# octocat/.github or another third repository
# .github/workflows/mirror-mingw-regex-to-octocat-mingw-regex.yml
name: Mirror mingw/regex to octocat/mingw-regex
on:
  schedule:
    - cron: "36 */6 * * *"
  workflow_dispatch:
jobs:
  mirror-mingw-regex-to-octocat-mingw-regex:
    runs-on: ubuntu-latest
    steps:
      - run: git clone --bare https://git.code.sf.net/p/mingw/regex .
      - run: git push --mirror "https://x:$TOKEN@github.com/octocat/mingw-regex.git"
        env:
          TOKEN: ${{ secrets.MINGW_REGEX_TOKEN }}
spyoungtech commented

If I recall correctly, the reason why this strategy is not used in this Action is because git clone --bare ... and git push --mirror is that --mirror will cause everything to be mirrored (as opposed to this action allowing branches to be selectively mirrored) and will delete branches on the remote not present on the source, which can be a destructive and undesirable behavior, especially if the goal is preservation.

In short, the behavior of --mirror is usually not what users actually want to do.

If you do wish to have this behavior, it is possible to configure this in the GIT_PUSH_ARGS option for this action to use --mirror. Since the clone/checkout process is not part of this action (you should use actions/checkout for example), you can also configure --bare in the action steps you use to clone your repository as well.

Couple of references you might find helpful:

Hope that helps answer your question.

  • 👍1
jcbhmr commented

Thanks for the detailed comparison! I'm using a tool that requires a user/repo slug to resolve against GitHub and doesn't accept non-GitHub Git repos 😤 so I think the basic git push --mirror is perfect for me. Thanks again for the explanation! 🙏