backport.yml

name: Backport PR

on:
  pull_request_target:
    types: [closed, labeled]

permissions:
  contents: write
  pull-requests: write

jobs:
  backport:
    name: Backport PR
    if: >
      github.event.pull_request.merged == true
      && contains(join(github.event.pull_request.labels.*.name, ','), 'backport')
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          fetch-depth: 0
          token: ${{ secrets.GITHUB_TOKEN }}

      - name: Create backport PRs
        uses: korthout/backport-action@v3
        with:
          github_token: ${{ secrets.GITHUB_TOKEN }}
          label_pattern: "^backport-to-(.+)$"
          # pull_title: "[Backport ${target_branch}] ${pull_title}"
          pull_title: "${pull_title}"
          pull_description: |
            Backport of #${pull_number} to `${target_branch}`.
            
            ---
            
            ${pull_description}
          merge_commits: "skip"
          copy_requested_reviewers: true
          copy_assignees: true
          copy_labels_pattern: "^(?!backport)"

      - name: Report backport status
        if: failure()
        uses: actions/github-script@v7
        with:
          script: |
            const { owner, repo } = context.repo;
            const pull_number = context.payload.pull_request.number;
            
            await github.rest.issues.createComment({
              owner,
              repo,
              issue_number: pull_number,
              body: `⚠️ **Backport failed!**\n\nThe automatic backport could not be completed. This might be due to merge conflicts.\n\nPlease manually cherry-pick the commits to the target branch:\n\n\`\`\`bash\ngit checkout <target-branch>\ngit cherry-pick -x ${context.payload.pull_request.merge_commit_sha}\n\`\`\`\n\nThen create a new PR targeting the branch.`
            });