merge.yaml

name: Fast-forward merge

on:
  issue_comment:
    types: [created, edited]

jobs:
  fast_forward:
    name: Fast-forward merge

    runs-on: ubuntu-latest

    if: |
      github.event.issue.pull_request &&
      github.event.issue.state == 'open' &&
      (
        github.event.comment.author_association == 'OWNER' ||
        github.event.comment.author_association == 'MEMBER' ||
        github.event.comment.author_association == 'COLLABORATOR'
      ) &&
      github.event.comment.body == '/fast-forward-merge'

    permissions:
      actions: write
      contents: write
      pull-requests: write

    steps:
      - name: Checkout
        uses: actions/checkout@v4
      - name: Minimize calling comment
        uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            await github.graphql(`mutation { minimizeComment(input: { subjectId: "${context.payload.comment.node_id}", classifier: OUTDATED }) { clientMutationId } }`)
            const { data: comments } = await github.rest.issues.listComments({
              ...context.repo,
              issue_number: ${{ github.event.issue.number }},
            });
            for (const comment of comments) {
              if (comment.user.login === 'github-actions[bot]' && comment.body.startsWith('Failure merging:')) {
                await github.graphql(`mutation { minimizeComment(input: { subjectId: "${comment.node_id}", classifier: OUTDATED }) { clientMutationId } }`)
              }
            }
      - name: Checkout pull request
        id: pr
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          gh pr checkout ${{ github.event.issue.number }}
          echo "base_ref=$(gh pr view ${{ github.event.issue.number }} --json baseRefName)" >> $GITHUB_OUTPUT
      - name: Fast-forward merge
        run: |
          export PR_COMMIT=$(git rev-parse HEAD)
          git checkout ${{ fromJSON(steps.pr.outputs.base_ref).baseRefName }}
          git merge --ff-only "$PR_COMMIT" 2>output.log
          git push origin ${{ fromJSON(steps.pr.outputs.base_ref).baseRefName }} 2>output.log
      - name: Post errors
        if: ${{ failure() }}
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          gh pr comment ${{ github.event.issue.number }} -b "Failure merging:
          \`\`\`
          $(cat output.log)
          \`\`\`"
      - name: Run CI
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          gh workflow run "Coverage & Documentation" -r ${{ fromJSON(steps.pr.outputs.base_ref).baseRefName }}