This GitHub Action mirrors a repository to another repository while rewriting git history to ignore certain files or directories. It is based on the original repository-mirroring-action by pixta-dev, but with some added features:

• It supports .mirrorignore file to ignore certain paths when mirroring.
• It adds .gitkeep and .private files to the ignored directories that exist on the last commit.
• It commits these changes as github.actor.

This action is perfect for maintaining a clean, public-facing mirror of a private repository.

1. It's recommended to set it to run on main branch pushes and deletions. You can configure the branch in the settings of the GitHub action.
2. It runs within a Docker environment, containing the pushed repository at /github/workspaces.
3. It uses git-filter-repo to rewrite git history, removing all paths (directories and files) specified in the .mirrorignore file. See the documentation for more details about git-filter-repo mechanisms.
4. If any removed directories were present on the last commit, they will be replaced with a directory containing .gitkeep and .private files.
5. These changes are committed and pushed to the mirror repository.

• All caveats present in git-filter-repo apply here. Check here for detailed limitations.
• Only one branch is mirrored, as set by main_branch action parameter.

Customize following example workflow (namely replace <username>/<target_repository_name> with the right information) and save as .github/workflows/main.yml on your source repository.

To find out how to create and add the GITLAB_SSH_PRIVATE_KEY, follow the steps below:

1. How to generate an SSH key pair. Recommended encryption would be at least 2048-bit RSA.
2. Add the public key to your gitlab account
3. Add the private key as a secret to your workflow. More information on creating and using secrets.

name: Mirroring

on:
  push:
    branches:
      - master

jobs:
  public_mirror:
    runs-on: ubuntu-latest
    steps:
      # <-- must use actions/checkout before mirroring!
      - uses: actions/checkout@v3
        with:
          fetch-depth: 0
      - uses: usher-labs/monorepo-package-mirror-action@main
        with:
          target_repo_url:
            git@github.com:<username>/<target_repository_name>.git
          ssh_private_key:
            # <-- use 'secrets' to pass credential information.
            ${{ secrets.SSH_PRIVATE_KEY }}
          main_branch: master

To avoid copying specific files or directories on the mirrored repository, you can add a .mirrorignore file to the root of the source repository.

# .mirrorignore example content
# Be aware: the mirrorignore parse isn't robust
# file path format:
# path/to/file.txt
# directory path format:
# path/to/dir or path/to/dir
# spaces on files or folders isn't supported.
# glob pattern isn't supported.
# negate paths with a leading !, for example:
# !contracts/evm

# won't copy the following files to the mirror repo
packages/broker
packages/validator
# to avoid copying again this action to the mirror
# rename to the appropriate action file
.github/workflows/public-mirror.yml

This action is based on the original repository-mirroring-action by pixta-dev. We've added features for more flexibility when mirroring repositories, especially when some files or directories need to be kept private.