automerge-from-merge-queue.yml

name: automerge from merge_queue

on:
  workflow_run:
    workflows:
      - CI
    types:
      - completed

concurrency:
  group: automerge-merge_queue-${{ github.event.workflow_run.event }}-${{ github.event.workflow_run.id }}
  cancel-in-progress: true

env:
  HOMEBREW_DEVELOPER: 1
  HOMEBREW_NO_AUTO_UPDATE: 1
  GH_REPO: ${{ github.repository }}
  GH_NO_UPDATE_NOTIFIER: 1
  GH_PROMPT_DISABLED: 1

jobs:
  status-check:
    runs-on: ubuntu-latest
    if: >
      github.repository_owner == 'Homebrew' &&
      github.event.workflow_run.conclusion != 'success' &&
      github.event.workflow_run.event == 'merge_group'
    outputs:
      pull-number: ${{ steps.pr.outputs.number }}
      publishable: ${{ steps.check-labels.outputs.publishable }}
      approved: ${{ steps.approval-status.outputs.approved }}
      complete: ${{ steps.approval-status.outputs.complete }}
      mergeable: ${{ steps.approval-status.outputs.mergeable }}
    permissions:
      contents: read
      pull-requests: read
      actions: read
    steps:
      - name: Get PR number
        id: pr
        env:
          GH_TOKEN: ${{ github.token }}
          WORKFLOW_RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.event.workflow_run.id }}
          QUERY: |-
            query($url: URI!) {
              resource(url: $url) {
                ... on WorkflowRun {
                  checkSuite {
                    commit {
                      associatedPullRequests(last: 1) {
                        nodes {
                          number
                        }
                      }
                    }
                  }
                }
              }
            }
        run: |
          number="$(
            gh api graphql \
              --field url="$WORKFLOW_RUN_URL" \
              --raw-field query="$QUERY" \
              --jq '.data.resource.checkSuite.commit.associatedPullRequests.nodes[].number'
          )"
          echo "number=$number" >> "$GITHUB_OUTPUT"

      - name: Check PR labels and timeline for merge queue events
        id: check-labels
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          PR: ${{ steps.pr.outputs.number }}
          QUERY: |-
            query ($owner: String!, $name: String!, $pr: Int!) {
              repository(owner: $owner, name: $name) {
                pullRequest(number: $pr) {
                  timelineItems(itemTypes: [REMOVED_FROM_MERGE_QUEUE_EVENT], last: 5) {
                    totalCount
                  }
                }
              }
            }
        run: |
          publishable=true
          while IFS='' read -r label
          do
            if [[ "$label" = "new formula" ]] ||
               [[ "$label" = "automerge-skip" ]] ||
               [[ "$label" = "pre-release" ]] ||
               [[ "$label" = "CI-published-bottle-commits" ]]
            then
              publishable=false
              break
            fi
          done < <(
            gh api \
              --header 'Accept: application/vnd.github+json' \
              --header 'X-GitHub-Api-Version: 2022-11-28' \
              "repos/{owner}/{repo}/pulls/$PR" \
              --jq '.labels[].name'
          )

          removed_from_merge_queue_count="$(
            gh api graphql \
              --field owner='{owner}' \
              --field name='{repo}' \
              --field pr="$PR" \
              --raw-field query="$QUERY" \
              --jq '.data.repository.pullRequest.timelineItems.totalCount'
          )"

          if [[ "$removed_from_merge_queue_count" -gt 3 ]]
          then
            # We've already tried to merge this PR multiple times.
            publishable=false
          fi

          echo "publishable=$publishable" >> "$GITHUB_OUTPUT"

      - name: Get approval and CI status
        if: fromJson(steps.check-labels.outputs.publishable)
        id: approval-status
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          PR: ${{ steps.pr.outputs.number }}
          QUERY: |-
            query ($owner: String!, $name: String!, $pr: Int!) {
              repository(owner: $owner, name: $name) {
                pullRequest(number: $pr) {
                  reviewDecision
                  commits(last: 1) {
                    nodes {
                      commit {
                        checkSuites(last: 100) {
                          nodes {
                            conclusion
                            workflowRun {
                              workflow {
                                name
                              }
                            }
                          }
                        }
                      }
                    }
                  }
                }
              }
            }
        run: |
          attempt=0
          max_attempts=5
          timeout=5

          while [[ "$attempt" -lt "$max_attempts" ]]
          do
            attempt=$(( attempt + 1 ))

            query_response="$(
              gh api graphql \
                --field owner='{owner}' \
                --field name='{repo}' \
                --field pr="$PR" \
                --raw-field query="$QUERY" \
                --jq '.data.repository.pullRequest'
            )"

            approved="$(
              jq --raw-output '.reviewDecision == "APPROVED"' <<< "$query_response"
            )"
            complete="$(
              jq --raw-output \
                '.commits.nodes[].commit.checkSuites.nodes |
                   map(select(.workflowRun.workflow.name == "CI")) |
                     last | .conclusion == "SUCCESS"' <<< "$query_response"
            )"
            # See https://github.com/octokit/octokit.net/issues/1763 for possible `mergeable_state` values.
            mergeable="$(
              gh api \
                --header 'Accept: application/vnd.github+json' \
                --header 'X-GitHub-Api-Version: 2022-11-28' \
                "repos/{owner}/{repo}/pulls/$PR" \
                --jq '(.mergeable_state == "clean") and (.draft | not)'
            )"

            if [[ "$approved" = "true" ]] &&
               [[ "$complete" = "true" ]] &&
               [[ "$mergeable" = "true" ]] ||
               [[ "$attempt" -eq "$max_attempts" ]]
            then
              break
            fi

            echo "::notice ::PR #$PR status:"
            echo "::notice ::Approved?    $approved"
            echo "::notice ::CI Complete? $complete"
            echo "::notice ::Mergeable?   $mergeable"
            echo "::notice ::Checking again in ${timeout}s..."
            sleep "$timeout"
            timeout=$(( timeout * 2 ))
          done

          {
            echo "approved=$approved"
            echo "complete=$complete"
            echo "mergeable=$mergeable"
          } >> "$GITHUB_OUTPUT"

  merge:
    runs-on: ubuntu-latest
    needs: status-check
    if: >
      fromJson(needs.status-check.outputs.publishable) &&
      fromJson(needs.status-check.outputs.approved) &&
      fromJson(needs.status-check.outputs.complete) &&
      fromJson(needs.status-check.outputs.mergeable)
    container:
      image: ghcr.io/homebrew/ubuntu22.04:master
    permissions:
      contents: read
      pull-requests: read
      actions: write # to dispatch publish workflow
    defaults:
      run:
        shell: bash
    steps:
      - name: Set up Homebrew
        uses: Homebrew/actions/setup-homebrew@master
        with:
          core: false
          cask: false
          test-bot: false

      - run: brew pr-publish "$PR"
        env:
          HOMEBREW_GITHUB_API_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          PR: ${{ needs.status-check.outputs.pull-number }}