Merge pull request with "merge" comment

merge-on-comment.yml

# Merges a pull request (if able) when a comment is added by a collaborator,
# contributor, or owner with the word "merge" as its only content

name: Merge on comment

on:
  issue_comment:
    types: [created]

jobs:
  merge-on-comment:
    name: Merge on comment
    if: |
      (
        github.event.issue.pull_request
        && github.event.comment.body == 'merge'
        && contains(
          'COLLABORATOR CONTRIBUTOR OWNER',
          github.event.comment.author_association
        )
      )
    runs-on: ubuntu-latest
    steps:
      - name: Response
        uses: thollander/actions-comment-pull-request@v2
        with:
          message: Attempting to merge your pull request. Check the **Actions** tab to investigate failures.
          comment_tag: merge-on-comment
          reactions: rocket
          pr_number: ${{ github.event.issue.number }}

      - name: Merge pull request
        uses: juliangruber/merge-pull-request-action@v1
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          number: ${{ github.event.issue.number }}
          method: squash

      - name: Failure
        if: failure()
        uses: thollander/actions-comment-pull-request@v2
        with:
          message: Pull request failed to merge.
          comment_tag: merge-on-comment
          reactions: "-1"
          pr_number: ${{ github.event.issue.number }}

      - name: Success
        if: success()
        uses: thollander/actions-comment-pull-request@v2
        with:
          message: Pull request merged successfully.
          comment_tag: merge-on-comment
          reactions: "+1"
          pr_number: ${{ github.event.issue.number }}

Here's a GitHub Workflow I pieced together this evening in order to merge a pull request with a comment as the trigger. Merge rules are still respected (i.e. required checks, approvals, etc. will still prevent merging).

Can be used as a way to prevent the editing of the pull request title before merging takes place (e.g. if squash merge is being used) or to provide outside contributors a way to merge their work without write access to the repository. (Note that the author_association check would need to be altered in that case.)