yarn-unlock.yml

name: Yarn Unlocker

# Short-cut for the common case of a PR having a merge conflict with only `yarn.lock`.
# Responds to a comment on a pull request containing "/yarn unlock"
# Test-merges the PR. If there's only one conflict, that being yarn.lock,
# it runs `yarn` (which will fix it) and pushes the merge commit.

on:
  issue_comment:
    types: [created]

permissions:
  contents: write
  issues: write
  pull-requests: write

jobs:
  merge-yarn-lock:
    if: contains(github.event.comment.html_url, '/pull/') && contains(github.event.comment.body, '/yarn unlock')
    runs-on: ubuntu-latest
    steps:
      - uses: actions/github-script@v7
        id: comment
        with:
          script: |
            const comment = await github.rest.issues.createComment({
              issue_number: context.issue.number,
              owner: context.repo.owner,
              repo: context.repo.repo,
              body: `Trying to merge yarn.lock... follow along at https://github.com/${context.repo.owner}/${context.repo.repo}/actions/runs/${{ github.run_id }}`
            })
            return comment.data.id
      - uses: actions/checkout@v4
        with:
          ref: refs/pull/${{ github.event.issue.number }}/head
          fetch-depth: 0
      - name: Use Node.js 18.x
        uses: actions/setup-node@v4
        with:
          node-version: 18.x
          cache: "yarn"
          cache-dependency-path: "yarn.lock"
      - run: yarn install --immutable --inline-builds
      - id: merge
        run: |
          git config --global user.name "${GITHUB_ACTOR}"
          git config --global user.email "${GITHUB_ACTOR}@users.noreply.github.com"
          git merge origin/main > ${{ runner.temp }}/merge.log || true
          # If there are no conflicts, we're done here
          if ! grep -q 'CONFLICT' ${{ runner.temp }}/merge.log; then
            echo needs-merge=false >> "$GITHUB_OUTPUT"
            exit 1
          fi
          # Abort *unless* there is only one conflict, that being yarn.lock
          if [ "$(grep -c 'CONFLICT' ${{ runner.temp }}/merge.log)" -eq 1 ] && grep -q 'Merge conflict in yarn.lock' ${{ runner.temp }}/merge.log; then
            exit 0
          fi
          echo cannot-fix=true >> "$GITHUB_OUTPUT"
          exit 1
      - if: failure() && steps.merge.outputs.needs-merge == 'false'
        uses: actions/github-script@v7
        with:
          script: |
            github.rest.issues.updateComment({
              comment_id: ${{ steps.comment.outputs.result }},
              owner: context.repo.owner,
              repo: context.repo.repo,
              body: 'No conflicts found.'
            })
      - if: failure() && steps.merge.outputs.cannot-fix == 'true'
        uses: actions/github-script@v7
        with:
          script: |
            github.rest.issues.updateComment({
              comment_id: ${{ steps.comment.outputs.result }},
              owner: context.repo.owner,
              repo: context.repo.repo,
              body: 'Cannot fix conflicts. Please merge manually.'
            })
      - run: |
          yarn install --no-immutable
          git add yarn.lock
          git commit -m 'chore: merge yarn.lock'
          git push origin HEAD
      - uses: actions/github-script@v7
        with:
          script: |
            github.rest.issues.updateComment({
              comment_id: ${{ steps.comment.outputs.result }},
              owner: context.repo.owner,
              repo: context.repo.repo,
              body: 'Merged yarn.lock!'
            })
      - if: failure() && !steps.merge.outputs.needs-merge && !steps.merge.outputs.cannot-fix
        uses: actions/github-script@v7
        with:
          script: |
            github.rest.issues.updateComment({
              comment_id: ${{ steps.comment.outputs.result }},
              owner: context.repo.owner,
              repo: context.repo.repo,
              body: `Something went wrong. Please look at [the logs](https://github.com/${context.repo.owner}/${context.repo.repo}/actions/runs/${{ github.run_id }}).`
            })