backstage/.github/workflows/sync_pull-requests-scheduled.yml

name: Sync Pull Requests Scheduled

on:
  schedule:
    # Every 30 minutes, processing a rotating batch of PRs
    - cron: '*/30 * * * *'
  workflow_dispatch:

permissions: {}

jobs:
  plan:
    permissions:
      pull-requests: read
    runs-on: ubuntu-latest
    timeout-minutes: 5
    outputs:
      matrix: ${{ steps.batch.outputs.matrix }}
      count: ${{ steps.batch.outputs.count }}
    steps:
      - name: Harden Runner
        uses: step-security/harden-runner@58077d3c7e43986b6b15fba718e8ea69e387dfcc # v2.15.1
        with:
          egress-policy: audit

      - name: Determine PR batch
        id: batch
        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
        with:
          script: |
            // 48 slots per day (one per 30-minute cron window).
            // Each PR is assigned a fixed slot via pr.number % 48, so
            // opening/closing other PRs never shifts the assignment.
            const totalSlots = 48;
            const now = new Date();
            const currentSlot =
              now.getUTCHours() * 2 + (now.getUTCMinutes() >= 30 ? 1 : 0);

            const prs = await github.paginate(github.rest.pulls.list, {
              owner: context.repo.owner,
              repo: context.repo.repo,
              state: 'open',
              per_page: 100,
            });

            const batch = prs.filter(
              pr => pr.number % totalSlots === currentSlot,
            );

            core.info(
              `Slot ${currentSlot}/${totalSlots}: ` +
              `${batch.length} PRs to process out of ${prs.length} open`,
            );

            const matrix = {
              include: batch.map(pr => ({ prNumber: String(pr.number) })),
            };

            core.setOutput('matrix', JSON.stringify(matrix));
            core.setOutput('count', String(batch.length));

  sync:
    needs: plan
    if: needs.plan.outputs.count > 0
    runs-on: ubuntu-latest
    timeout-minutes: 5
    strategy:
      matrix: ${{ fromJSON(needs.plan.outputs.matrix) }}
      fail-fast: false
      max-parallel: 1
    steps:
      - name: Harden Runner
        uses: step-security/harden-runner@58077d3c7e43986b6b15fba718e8ea69e387dfcc # v2.15.1
        with:
          egress-policy: audit

      - name: Backstage PR automation
        uses: backstage/actions/pr-automation@2cd6978b476cbdc39fec48346f8b6ca13199dd6a # v0.7.8
        with:
          app-id: ${{ secrets.BACKSTAGE_GOALIE_APPLICATION_ID }}
          private-key: ${{ secrets.BACKSTAGE_GOALIE_PRIVATE_KEY }}
          installation-id: ${{ secrets.BACKSTAGE_GOALIE_INSTALLATION_ID }}
          project-owner: backstage
          project-number: '14'
          pr-number: ${{ matrix.prNumber }}
          action: synchronize
          required-checks: |
            DCO
            E2E Linux 22.x
            E2E Linux 24.x
            Test 22.x
            Test 24.x
            Verify 22.x
            Verify 24.x