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
    env:
      REPO: ${{ github.repository }}
      PR_NUMBER: ${{ github.event.pull_request.number }}
    steps:
      - name: Check out code
        uses: actions/checkout@v4.1.2

      - name: Setup gh-actions-cache extension
        run: gh extension install actions/gh-actions-cache

      - name: Retrieve Trunk SHA
        id: get-sha
        run: |
          SHA=$(gh pr view -R $REPO $PR_NUMBER --json mergeCommit --jq .mergeCommit.oid)
          echo "sha=$SHA" >> $GITHUB_OUTPUT

      - name: Cleanup Caches
        env:
          TRUNK_SHA: ${{ steps.get-sha.outputs.sha }}
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          set +e

          PR_BRANCH=refs/pull/$PR_NUMBER/merge          
          echo "Fetching list of cache keys for the PR branch ($PR_BRANCH)"
          PR_CACHE_KEYS=$(gh actions-cache list -R $REPO -B $PR_BRANCH | cut -f 1)

          echo "Deleting caches for PR branch ($PR_BRANCH)..."
          for CACHE_KEY in $PR_CACHE_KEYS; do
              gh actions-cache delete $CACHE_KEY -R $REPO -B $PR_BRANCH --confirm
          done

          if [[ -n "$TRUNK_SHA" ]]; then
            echo "Found corresponding merge commit $TRUNK_SHA"
            QUEUE_BRANCH="gh-readonly-queue/develop/pr-${PR_NUMBER}-${TRUNK_SHA}"
            echo "Fetching list of cache keys for the merge queue branch ($QUEUE_BRANCH)"            
            QUEUE_CACHE_KEYS=$(gh actions-cache list -R $REPO -B $QUEUE_BRANCH | cut -f 1)
          
            echo "Deleting caches for merge queue branch ($QUEUE_BRANCH)..."
            for CACHE_KEY in $QUEUE_CACHE_KEYS; do
                gh actions-cache delete $CACHE_KEY -R $REPO -B $QUEUE_BRANCH --confirm
            done
          fi

          echo "Done"