cache-sync.yml

# This workflow is necessary in order for the the proper Event to be used
# so we can pull the source and destination branch details
name: PR Cache Sync

on:
  pull_request:
    branches: [main]
    types:
      - closed
    paths:
      - Dockerfile

env:
  DOCKER_BUILDKIT: "1"
  COSIGN_EXPERIMENTAL: "1"

jobs:
  cache-sync:
    name: PR cache sync
    runs-on: ubuntu-latest
    if: github.event.pull_request.merged == true
    steps:
      - name: Install regctl
        uses: iarekylew00t/regctl-installer@c552a6ea85fb38c900cb63feccaa69145ad0883c # v3.1.4

      - name: Copy PR build cache to branch
        shell: bash
        run: |
          IMAGE_NAME=$(echo "${GITHUB_REPOSITORY/docker-/}" | tr '[:upper:]' '[:lower:]')
          BASE_BRANCH=$(echo "${GITHUB_BASE_REF//[^a-zA-Z0-9]/-}" | tr '[:upper:]' '[:lower:]')
          HEAD_BRANCH=$(echo "${GITHUB_HEAD_REF//[^a-zA-Z0-9]/-}" | tr '[:upper:]' '[:lower:]')
          echo "ttl.sh/$IMAGE_NAME:$HEAD_BRANCH --> ttl.sh/$IMAGE_NAME:$BASE_BRANCH"
          regctl image copy \
            --verbosity info \
            --digest-tags \
            --force-recursive \
            "ttl.sh/$IMAGE_NAME:$HEAD_BRANCH" \
            "ttl.sh/$IMAGE_NAME:$BASE_BRANCH"