name: Clear expensive caches to prevent unbounded growth

on:
  schedule:
    # Run every 4 months at 10 AM UTC (2 AM PDT)
    - cron: 0 10 5 */4 *

  # manual
  workflow_dispatch:

permissions:
  contents: read

jobs:
  bazel-repository-cache:
    strategy:
      fail-fast: false   # Don't cancel all jobs if one fails.
      matrix:
        os: [ubuntu-latest, macos-latest, windows-latest]
    name: Clear Bazel repository cache ${{ matrix.os }}
    runs-on: ${{ matrix.os }}
    permissions:
      actions: write # permission is required to delete caches
      contents: read
    steps:
      - uses: actions/cache@627f0f41f6904a5b1efbaed9f96d9eb58e92e920 # v3.2.4
        with:
          path: ${{ github.workspace }}/${{ steps.output.outputs.repository-cache }}
          key: repository-cache-${{ github.ref_name }}-${{ runner.os }}-reset-${{ github.sha }}

      - name: Create an empty cache with a single file
        run: |
          rm -rf .repository-cache
          mkdir -p .repository-cache
          touch .repository-cache/reset_file