backport.yml

name: Backport

on:
  pull_request_target:
    types: [closed, labeled]

permissions:
  contents: write
  pull-requests: write

jobs:
  backport:
    name: Backport PR
    runs-on: ubuntu-latest
    # Only run on merged PRs that carry a backport label. The `labeled` event
    # lets you trigger a backport after the PR is already merged by adding the
    # label late.
    if: >
      github.event.pull_request.merged == true &&
      (
        github.event.action == 'closed' ||
        startsWith(github.event.label.name, 'backport ')
      )
    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Create backport PRs
        uses: korthout/backport-action@d07416681cab29bf2661702f925f020aaa962997 # v3.4.1
        with:
          # Act only on labels shaped like "backport <target-branch>",
          # e.g. "backport main".
          label_pattern: '^backport ([^ ]+)$'
          # Reuse the source title verbatim. A prefix here would push the
          # conventional-commit type out of first position and fail the PR
          # Title Check; the "backport" label marks these PRs instead.
          pull_title: '${pull_title}'
          pull_description: |
            Automated backport of #${pull_number} to `${target_branch}`.
          add_labels: backport
          # Carry the original PR's labels onto the backport PR, except the
          # "backport <branch>" label itself — copying it would re-trigger this
          # workflow when the generated PR is merged.
          copy_labels_pattern: '^(?!backport ).*'