clear_cache.yaml

# This job cleans up the unnecessary caches created on PRs.
# https://docs.github.com/en/actions/using-workflows/caching-dependencies-to-speed-up-workflows#force-deleting-cache-entries
name: cleanup caches by a branch
on:
  # Only runs on the PRs are closed, regardless of it is merged or not.
  # https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#running-your-pull_request-workflow-when-a-pull-request-merges
  pull_request:
    types:
      - closed

jobs:
  cleanup:
    runs-on: ubuntu-latest
    steps:
      - name: Check out code
        uses: actions/checkout@v3

      - name: Cleanup
        run: |
          gh extension install actions/gh-actions-cache

          REPO=${{ github.repository }}
          BRANCH="refs/pull/${{ github.event.pull_request.number }}/merge"

          echo "Fetching list of cache key"
          cacheKeysForPR=$(gh actions-cache list -R $REPO -B $BRANCH | cut -f 1 )

          ## Setting this to not fail the workflow while deleting cache keys.
          set +e
          echo "Deleting caches..."
          for cacheKey in $cacheKeysForPR
          do
              gh actions-cache delete $cacheKey -R $REPO -B $BRANCH --confirm
          done
          echo "Done"
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}