recreate-linux-runners.yml

name: Recreate Linux self-hosted runners

on:
  workflow_dispatch:
  schedule:
    # Once each 24 hours, at 1 during the night
    - cron: "0 1 * * *"
  workflow_run:
    workflows:
      - CI
    types:
      - completed

concurrency:
  group: recreate-linux-runners-${{ github.event.workflow_run.id || github.ref }}
  cancel-in-progress: true

permissions:
  contents: read

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

jobs:
  check:
    if: >
      github.repository_owner == 'Homebrew' &&
      (github.event_name != 'workflow_run' || github.event.workflow_run.event == 'pull_request')
    runs-on: ubuntu-latest
    outputs:
      recreate: ${{ steps.check.outputs.recreate }}
    permissions:
      actions: read # for `gh run download`
      pull-requests: read # for `gh api`
    steps:
      - uses: Homebrew/actions/find-related-workflow-run-id@master
        if: github.event_name == 'workflow_run'
        with:
          run-id: ${{ github.event.workflow_run.id }}
          workflow-name: Triage tasks

      - name: Download `event_payload` artifact
        if: github.event_name == 'workflow_run'
        uses: Homebrew/actions/gh-try-download@master
        with:
          artifact-name: event_payload
          workflow-id: ${{ env.workflow_run_id }}

      - name: Check if runner needs to be recreated
        id: check
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          recreate=true

          if [[ "$GITHUB_EVENT_NAME" = "workflow_run" ]]
          then
            PR="$(jq --raw-output .number event.json)"

            recreate="$(
              gh api \
                --header 'Accept: application/vnd.github+json' \
                --header 'X-GitHub-Api-Version: 2022-11-28' \
                "repos/{owner}/{repo}/pulls/$PR" \
                --jq 'any(.labels[].name; .== "CI-linux-self-hosted")'
            )"
          fi

          echo "recreate=$recreate" >> "$GITHUB_OUTPUT"

  recreate:
    needs: check
    if: >
      github.repository_owner == 'Homebrew' &&
      (github.event_name != 'workflow_run' || github.event.workflow_run.event == 'pull_request') &&
      fromJson(needs.check.outputs.recreate)
    runs-on: ubuntu-latest
    env:
      # TODO agree on one label for all runners
      RUNNER_LABEL: TODO
    strategy:
      matrix:
        runner_name:
          - linux-self-hosted-1
    steps:
      - name: Set up Cloud SDK
        uses: google-github-actions/setup-gcloud@v0.2.1
        with:
          project_id: ${{ secrets.GCP_PROJECT_ID }}
          service_account_key: ${{ secrets.GCP_SA_KEY }}
          export_default_credentials: true

      - name: Wait for idle runner
        id: killable
        uses: Homebrew/actions/wait-for-idle-runner@master
        with:
          runner_name: ${{ matrix.runner_name }}
          github_token: ${{ secrets.HOMEBREW_GITHUB_PUBLIC_REPO_TOKEN }}

      - name: Kill runner and create a new one
        if: ${{ steps.killable.outputs.runner-found == 'true' && steps.killable.outputs.runner-idle == 'true' }}
        uses: Homebrew/actions/create-gcloud-instance@master
        with:
          runner_name: ${{ matrix.runner_name }}
          gcp_project_id: ${{ secrets.GCP_PROJECT_ID }}
          gcp_service_account: ${{ secrets.GCP_SERVICE_ACCOUNT }}
          gcp_sa_key: ${{ secrets.GCP_SA_KEY }}
          github_token: ${{ secrets.HOMEBREW_GITHUB_PUBLIC_REPO_TOKEN }}