delete-caches.yml

name: Cleanup Caches

# See: 
# https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/caching-dependencies-to-speed-up-workflows#force-deleting-cache-entries

on:
  pull_request:
    types:
      - closed

jobs:
  cleanup-branch-caches:
    runs-on: ubuntu-latest
    permissions:
      # `actions:write` permission is required to delete caches
      #   See also: https://docs.github.com/en/rest/actions/cache?apiVersion=2022-11-28#delete-a-github-actions-cache-for-a-repository-using-a-cache-id
      actions: write
      contents: read
    steps:
      - name: Check out code
        uses: actions/checkout@v4.1.2

      - name: Cleanup Branch Caches
        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 }}