automatic-rebase.yml

on:
  issue_comment:
    types:
      - created
  pull_request_target:
    types:
      - auto_merge_enabled

env:
  AUTO_REBASE_PERSONAL_ACCESS_TOKEN:
    ${{ secrets.AUTO_REBASE_PERSONAL_ACCESS_TOKEN }}

jobs:
  check-token:
    if: |
      (
        github.event.issue.pull_request &&
        contains(github.event.comment.body, '/rebase')
      ) ||
      github.event_name == 'pull_request_target'

    runs-on: ubuntu-latest

    steps:
      - if: "! env.AUTO_REBASE_PERSONAL_ACCESS_TOKEN"
        name: Prompt to add a token
        uses: peter-evans/create-or-update-comment@v1
        with:
          issue-number: ${{ github.event.issue.number || github.event.number }}
          body: |
            To automatically rebase, you need to add a [personal access token](https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token) with the name `AUTO_REBASE_PERSONAL_ACCESS_TOKEN` to the [secrets section of this repo](https://github.com/${{ github.event.repository.full_name }}/settings/secrets/actions).

            Once this is done, you can try the `/rebase` command again.

      - if: github.event.comment
        name: React to the triggering comment
        uses: peter-evans/create-or-update-comment@v1
        with:
          comment-id: ${{ github.event.comment.id }}
          reactions:
            ${{ env.AUTO_REBASE_PERSONAL_ACCESS_TOKEN && '+1' || '-1' }}

      - if: "! env.AUTO_REBASE_PERSONAL_ACCESS_TOKEN"
        name: Return a failing state if we have no token
        run: exit 1

  rebase:
    needs: check-token
    name: Rebase

    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v2
        with:
          token: ${{ env.AUTO_REBASE_PERSONAL_ACCESS_TOKEN }}
          fetch-depth: 0

      - name: Rebase on top of the default branch
        uses: cirrus-actions/rebase@1.7
        env:
          GITHUB_TOKEN: ${{ env.AUTO_REBASE_PERSONAL_ACCESS_TOKEN }}

      - if: failure()
        name: Notify of the failure
        uses: peter-evans/create-or-update-comment@v1
        with:
          issue-number: ${{ github.event.issue.number || github.event.number }}
          body: |
            Automatic rebasing for this issue has failed :disappointed:

            You'll have to rebase this one manually, I'm afraid.

      - if: success() && github.event.comment
        name: React to the triggering comment
        uses: peter-evans/create-or-update-comment@v1
        with:
          comment-id: ${{ github.event.comment.id }}
          reactions: hooray