command-backport.yml

name: Backport into stable

on:
  # This trigger can be problematic, see: https://securitylab.github.com/resources/github-actions-preventing-pwn-requests/
  # In our case it is fine since we only run it on merged Pull Requests and do not execute any of the repo code itself.
  pull_request_target:
    types: [closed, labeled]

permissions:
  contents: write # so it can comment
  pull-requests: write # so it can create pull requests
  issues: write
  actions: write # It may have to backport changes to the CI as well.

jobs:
  backport:
    name: Backport pull request
    runs-on: ubuntu-latest

    # The 'github.event.pull_request.merged' ensures that it got into master:
    if: >
      ( !startsWith(github.event.pull_request.base.ref, 'stable') ) &&
      (
        github.event_name == 'pull_request_target' &&
        github.event.pull_request.merged &&
        github.event.pull_request.base.ref == 'master' &&
        contains(github.event.pull_request.labels.*.name, 'A4-needs-backport')
      )
    steps:
      - uses: actions/checkout@v4

      - name: Generate token
        id: generate_token
        uses: tibdex/github-app-token@v2.1.0
        with:
          app_id: ${{ secrets.CMD_BOT_APP_ID }}
          private_key: ${{ secrets.CMD_BOT_APP_KEY }}

      - name: Create backport pull requests
        uses: korthout/backport-action@v3
        id: backport
        with:
          target_branches: stable2407 stable2409 stable2412
          merge_commits: skip
          github_token: ${{ steps.generate_token.outputs.token }}
          pull_description: |
            Backport #${pull_number} into `${target_branch}` from ${pull_author}.

            See the [documentation](https://github.com/paritytech/polkadot-sdk/blob/master/docs/BACKPORT.md) on how to use this bot.

            <!--
              # To be used by other automation, do not modify:
              original-pr-number: #${pull_number}
            -->
          pull_title: |
            [${target_branch}] Backport #${pull_number}
          experimental: >
            {
              "conflict_resolution": "draft_commit_conflicts"
            }
          copy_assignees: true

      - name: Label Backports
        if: ${{ steps.backport.outputs.created_pull_numbers != '' }}
        uses: actions/github-script@v7
        with:
          script: |
            const pullNumbers = '${{ steps.backport.outputs.created_pull_numbers }}'.split(' ');

            for (const pullNumber of pullNumbers) {
              await github.rest.issues.addLabels({
                issue_number: parseInt(pullNumber),
                owner: context.repo.owner,
                repo: context.repo.repo,
                labels: ['A3-backport']
              });
              console.log(`Added A3-backport label to PR #${pullNumber}`);
            }

      - name: Request Review
        if: ${{ steps.backport.outputs.created_pull_numbers != '' }}
        uses: actions/github-script@v7
        with:
          script: |
            const pullNumbers = '${{ steps.backport.outputs.created_pull_numbers }}'.split(' ');
            const reviewer = '${{ github.event.pull_request.user.login }}';

            for (const pullNumber of pullNumbers) {
              await github.pulls.requestReviewers({
                owner: context.repo.owner,
                repo: context.repo.repo,
                pull_number: parseInt(pullNumber),
                reviewers: [ reviewer ]
              });
              console.log(`Requested review from ${reviewer} for PR #${pullNumber}`);
            }