backport.yml

name: Backport merged pull request
on:
  pull_request_target:
    types: [closed, labeled]
permissions:
  contents: write # so it can comment
  pull-requests: write # so it can create pull requests
jobs:
  backport:
    name: Backport pull request
    runs-on: ubuntu-latest
    # Don't run on closed unmerged pull requests
    if: >
      github.event.pull_request.merged
      && (
        github.event.action == 'closed'
        || (
          github.event.action == 'labeled'
          && contains(github.event.label.name, 'backport')
        )
      )
    steps:
      - uses: actions/checkout@v4
        with:
            # Token for git actions, e.g. git push see https://github.com/korthout/backport-action/issues/379
            token: ${{ secrets.BACKPORT_ACTION_PAT }}
      - name: Get issues
        id: get-issues
        uses: mondeja/pr-linked-issues-action@v2
        env:
          GITHUB_TOKEN: ${{ secrets.BACKPORT_ACTION_PAT }}
      - name: Create backport pull requests
        id: create_backport_pr
        uses: korthout/backport-action@v4
        with:
          # Token for git actions, see https://github.com/korthout/backport-action/issues/379
          github_token: ${{ secrets.BACKPORT_ACTION_PAT }}
          auto_merge_method: squash
          auto_merge_enabled: true
          copy_assignees: true
          copy_milestone: true
          copy_requested_reviewers: true
          add_labels: Backport
          pull_description: |-
            # Description
            Backport of #${pull_number} to `${target_branch}`.

            Fixes #${{ steps.get-issues.outputs.issues }}

          experimental: >
            {
              "conflict_resolution": "draft_commit_conflicts"
            }
      - name: Link all backport PRs to original issue
        if: ${{ steps.get-issues.outputs.issues != '' && steps.create_backport_pr.outputs.created_pull_numbers != '' }}
        uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.BACKPORT_ACTION_PAT }}
          script: |
            const issueNumbers = "${{ steps.get-issues.outputs.issues }}".split(',').map(s => s.trim()).filter(Boolean);
            const prNumbers = "${{ steps.create_backport_pr.outputs.created_pull_numbers }}".split(' ').map(s => s.trim()).filter(Boolean);

            for (const prNumber of prNumbers) {
              const { data: pr } = await github.rest.pulls.get({
                owner: context.repo.owner,
                repo: context.repo.repo,
                pull_number: Number(prNumber)
              });

              for (const issueNumber of issueNumbers) {
                const { data: issue } = await github.rest.issues.get({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  issue_number: Number(issueNumber)
                });

                console.log(`Linking PR #${prNumber} to issue #${issueNumber}`);

                await github.graphql(`
                  mutation AddLinkedIssue($pullRequestId: ID!, $issueId: ID!) {
                    addLinkedIssue(input: {
                      pullRequestId: $pullRequestId,
                      issueId: $issueId
                    }) {
                      pullRequest {
                        number
                      }
                    }
                  }
                `, {
                  pullRequestId: pr.node_id,
                  issueId: issue.node_id
                });
              }
            }