Github Repo Mirror

GitHub Repo Mirroring

Trigger: Use when setting up repository mirrors, migrating repos between platforms, or keeping forks in sync.

Mirror Types

One-Time Mirror

Clone with Full History

# Bare clone (all branches, all tags, no working tree)
git clone --mirror https://github.com/owner/repo.git
cd repo.git

# Push to new remote
git remote set-url origin https://github.com/new-owner/repo.git
git push --mirror

Or Single Command

# From GitHub → GitHub
gh repo clone owner/repo -- --mirror
cd repo.git
gh repo create new-owner/repo --public --push --source=.

# From GitHub → GitLab
git clone --mirror https://github.com/owner/repo.git
cd repo.git
git remote set-url origin https://gitlab.com/new-owner/repo.git
git push --mirror

# From GitLab → GitHub
git clone --mirror https://gitlab.com/owner/repo.git
cd repo.git
git remote set-url origin https://github.com/new-owner/repo.git
git push --mirror

Automated Mirror (GitHub Actions)

GitHub → GitLab

name: Mirror to GitLab
on:
  push:
    branches: ['*']
    tags: ['*']
jobs:
  mirror:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - uses: yesolutions/mirror-action@v0.7
        with:
          REMOTE: "https://gitlab.com/owner/repo.git"
          GIT_USERNAME: ${{ secrets.GITLAB_USER }}
          GIT_PASSWORD: ${{ secrets.GITLAB_TOKEN }}

GitHub → GitHub (Org/User transfer)

name: Mirror to Secondary
on:
  schedule:
    - cron: '0 */6 * * *'     # Every 6 hours
  workflow_dispatch:            # Manual trigger
jobs:
  mirror:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - run: |
          git remote add mirror https://x-access-token:${{ secrets.MIRROR_TOKEN }}@github.com/org/mirror-repo.git
          git push --mirror mirror

GitHub → GHCR Backup (Archival)

# Archive as a bundle (portable single file)
git bundle create repo-backup-$(date +%Y%m%d).bundle --all
git bundle verify repo-backup-*.bundle

Multi-Platform Mirroring

# Set up multiple push targets
git remote add github https://github.com/owner/repo.git
git remote add gitlab https://gitlab.com/owner/repo.git
git remote add bitbucket https://bitbucket.org/owner/repo.git

# Push to all
git push --all github
git push --all gitlab
git push --all bitbucket

Using gh CLI for Transfers

# Transfer repo to another user/org
gh api repos/:owner/:repo/transfer \
  --method POST \
  --field new_owner=new-org

# Rename repo
gh repo edit --name new-name

# Transfer with issues and PRs
# NOTE: gh transfer API doesn't move issues — use third-party tools

Pitfalls

• Mirror ≠ sync: Mirror copies git data; issues, PRs, wikis, and releases must be migrated separately
• Large repos: --mirror clones everything — for repos >1GB use --filter=blob:none for partial
• CI secrets: Mirror jobs need tokens with repo scope in the destination
• Deleted branches: --mirror push deletes branches not in the source — use --all instead for additive sync
• GitHub Actions artifacts: Not included in mirror — use gh run download separately

Verification

# Verify mirror completeness
git ls-remote origin | wc -l             # Source refs
git ls-remote mirror | wc -l             # Mirror refs — should match

# Check branches and tags matching
diff <(git ls-remote origin | awk '{print $2}' | sort) \
     <(git ls-remote mirror | awk '{print $2}' | sort)