cleanup-cache-at-pr-closing.yml

###############################################################################
# A Github repo has max 10 GB of cache.
# https://github.blog/changelog/2021-11-23-github-actions-cache-size-is-now-increased-to-10gb-per-repository/
#
# To avoid "cache thrashing" by their cache eviction policy it is recommended
# to apply a cache cleanup workflow at PR closing to dele cache leftovers of
# the current branch:
# https://docs.github.com/en/actions/using-workflows/caching-dependencies-to-speed-up-workflows#force-deleting-cache-entries
###############################################################################

name: ocelot.social cache cleanup on pr closing

on:
  pull_request:
    types:
      - closed

jobs:
  clean-branch-cache:
    name: Cleanup branch cache
    runs-on: ubuntu-latest
    continue-on-error: true
    steps:
      - name: Checkout code
        uses: actions/checkout@6d193bf28034eafb982f37bd894289fe649468fc # v4.1.7

      - 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 )
          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 }}