# Restores the n8n + runners image tarball (produced by build-n8n-docker
# under the variant+SHA-derived cache key) and loads both images into the
# local docker daemon.
#
# After this action runs, `n8nio/n8n:local` and `n8nio/runners:local` are
# present on the runner.
#
# If the cache entry has been evicted (e.g. Blacksmith cache thrash between
# prepare-docker and slow shards), the action falls back to invoking
# build-n8n-docker, which leaves both images tagged in dockerd and re-saves
# the tarball to cache as a side effect.

name: 'Load n8n Docker images from cache'
description: 'Restores the zstd-compressed n8n + runners image tarball from the variant+SHA-keyed GHA cache and loads both images into the local docker daemon. Falls back to rebuilding on cache miss.'

inputs:
  build-variant:
    description: 'Variant of the image to load. Must match what build-n8n-docker used (standard or coverage).'
    required: false
    default: 'standard'

runs:
  using: 'composite'
  steps:
    - name: Restore image tarball from cache
      id: restore
      uses: actions/cache/restore@640a1c2554105b57832a23eea0b4672fc7a790d5 # v4.2.3
      with:
        key: n8n-docker-image-${{ inputs.build-variant }}-${{ github.sha }}
        path: /tmp/n8n-image.tar.zst

    - name: Load n8n and runners images into docker
      if: steps.restore.outputs.cache-hit == 'true'
      shell: bash
      run: zstd -d -c /tmp/n8n-image.tar.zst | docker load

    - name: Warn on cache miss
      if: steps.restore.outputs.cache-hit != 'true'
      shell: bash
      env:
        BUILD_VARIANT: ${{ inputs.build-variant }}
        GITHUB_SHA: ${{ github.sha }}
      run: |
        echo "::warning::Cache miss for n8n-docker-image-$BUILD_VARIANT-$GITHUB_SHA (SHA $GITHUB_SHA); falling back to rebuild via build-n8n-docker."

    - name: Rebuild image on cache miss
      if: steps.restore.outputs.cache-hit != 'true'
      uses: ./.github/actions/build-n8n-docker
      with:
        build-variant: ${{ inputs.build-variant }}
