auto-backport.yml

name: Auto-backport
on:
  pull_request:
    types: [closed, labeled]

jobs:
  create-backport:
    if: github.event.pull_request.merged == true && (contains(github.event.pull_request.labels.*.name, 'backport') && github.event.action == 'closed' || github.event.label.name == 'backport')
    runs-on: ubuntu-22.04
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - uses: tibdex/github-app-token@v2.1.0
        id: generate-token
        with:
          app_id: ${{ secrets.METABASE_BOT_APP_ID }}
          private_key: ${{ secrets.METABASE_BOT_APP_PRIVATE_KEY }}
      - uses: ./.github/actions/find-squashed-commit
        name: Find commit
        id: find_commit
        with:
          pull-request-number: ${{ github.event.pull_request.number }}
          base-ref: ${{ github.event.pull_request.base.ref }}

      - uses: ./.github/actions/get-latest-release-branch
        name: Get latest release branch
        id: get_latest_release_branch

      - id: create_backport_pull_request
        name: Create backport pull request
        run: |
          git config --global user.email "metabase-bot@metabase.com"
          git config --global user.name "Metabase bot"

          BACKPORT_BRANCH="backport-$COMMIT"

          # Checkout the target branch and create a new backport branch
          git checkout ${TARGET_BRANCH}
          git fetch --all
          git checkout -b ${BACKPORT_BRANCH}
          git cherry-pick ${COMMIT} || true

          CONFLICTS=$(git ls-files -u | wc -l)
          if [ "$CONFLICTS" -gt 0 ]; then
            git cherry-pick --abort

            echo "Could not cherry pick because of a conflict"
            echo "has-conflicts=true" >> $GITHUB_OUTPUT

            # Add a shell script for resolving conflicts
            echo "git reset HEAD~1" > ./backport.sh
            echo "rm ./backport.sh" >> ./backport.sh
            echo "git cherry-pick ${COMMIT}" >> ./backport.sh
            echo "echo 'Resolve conflicts and force push this branch'" >> ./backport.sh
            chmod +x ./backport.sh
            git add ./backport.sh
            git commit -m "Add backport resolution script"

            PR_BODY=$(cat <<-END
            #${ORIGINAL_PULL_REQUEST_NUMBER}
            > [!IMPORTANT]
            > Manual conflict resolution is required.
            Checkout the branch and run \`./backport.sh\` script. Force push your changes after cherry-picking.
          END
            )
          else
            echo "has-conflicts=false" >> $GITHUB_OUTPUT
            PR_BODY="#${ORIGINAL_PULL_REQUEST_NUMBER}"
          fi

          git push -u origin ${BACKPORT_BRANCH}

          BACKPORT_PR_URL=$(gh pr create --base "${TARGET_BRANCH}" --head "${BACKPORT_BRANCH}" --label "was-backported" --assignee "${GITHUB_ACTOR}" --title "🤖 backported \"${ORIGINAL_TITLE}\"" --body "${PR_BODY}")
          BACKPORT_PR_NUMBER=${BACKPORT_PR_URL##*/}

          echo "backport_pr_number=$BACKPORT_PR_NUMBER" >> $GITHUB_OUTPUT
          echo "New PR has been created"

          git checkout master
        env:
          TARGET_BRANCH: ${{ steps.get_latest_release_branch.outputs.branch-name }}
          ORIGINAL_PULL_REQUEST_NUMBER: ${{ github.event.pull_request.number }}
          ORIGINAL_TITLE: ${{ github.event.pull_request.title }}
          GITHUB_TOKEN: ${{ steps.generate-token.outputs.token }}
          COMMIT: ${{ steps.find_commit.outputs.commit }}

      - name: Auto approve backport PR
        if: ${{ steps.create_backport_pull_request.outputs.has-conflicts == 'false' }}
        uses: juliangruber/approve-pull-request-action@v1
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          number: ${{ steps.create_backport_pull_request.outputs.backport_pr_number }}

      - name: Enable Pull Request Automerge
        if: ${{ steps.create_backport_pull_request.outputs.has-conflicts == 'false' }}
        uses: peter-evans/enable-pull-request-automerge@v2
        with:
          token: ${{ steps.generate-token.outputs.token }}
          pull-request-number: ${{ steps.create_backport_pull_request.outputs.backport_pr_number }}
          merge-method: squash

      - uses: ./.github/actions/notify-pull-request
        if: ${{ steps.create_backport_pull_request.outputs.has-conflicts == 'true' }}
        with:
          include-log: false
          message: Manual conflict resolution is required

      - uses: ./.github/actions/notify-pull-request
        if: ${{ failure() }}
        with:
          include-log: true
          message: Something went wrong while creating a backport