clone-docker-image-action.yaml

---
  name: Reusable workflow to clone a Docker image from one registry to another
  on:
    workflow_call:
      inputs:
        source_image: 
          description: The source image to clone
          required: true
          type: string
        source_registry:
          description: The source registry
          required: true
          type: string
        target_image:
          description: The target image to clone
          required: true
          type: string
        target_registry:
          description: 'The target registry'
          required: true
          type: string
        platforms:
          description: 'The platforms to clone'
          required: false
          type: string
          default: '["linux/arm64", "linux/amd64"]'
        suffix:
          description: 'The suffix to append to the target image'
          required: false
          type: string
          default: ''
        is_latest:
          description: 'Whether to tag the image as latest'
          required: false
          type: boolean
          default: false
      secrets: 
        source_registry_token:
          description: The Github token or similar to authenticate with for the registry.
          required: true
        target_registry_token:
          description: The Github token or similar to authenticate with for the registry.
          required: true
        source_registry_username:
          description: The source registry username
          required: true
        target_registry_username:
          description: The target registry username
          required: true
  
  jobs:
    check-image-exists:
      strategy:
        matrix:
          platform: ${{ fromJson(inputs.platforms) }}
      runs-on: ubuntu-latest
      steps:
        - name: Login to source container registry ${{ inputs.source_registry }}
          uses: docker/login-action@v3
          with:
            registry: ${{ inputs.source_registry }}
            username: ${{ secrets.source_registry_username }}
            password: ${{ secrets.source_registry_token }}

        - name: Pull the source image; verify it exists
          run: 
            docker pull "$SOURCE_IMAGE" --platform=${{ matrix.platform }}
          env:
            SOURCE_IMAGE: ${{ inputs.source_registry }}/${{ inputs.source_image }}
          shell: bash
    create-tags:
      runs-on: ubuntu-latest
      outputs:
        tags: ${{ steps.tags-converter.outputs.TAGS }}
      steps:
        - name: docker metadata for tags
          id: tags-metadata
          uses: docker/metadata-action@v5
          with:
            flavor: |
              latest=${{ inputs.is_latest }}
              suffix=${{ inputs.suffix }}
            tags: |
              raw,latest
              type=ref,event=branch
              type=ref,event=pr
              type=ref,event=tag
              type=semver,pattern={{version}}
              type=semver,pattern={{major}}.{{minor}}

        - name: Convert tags to JSON array
          id: tags-converter
          run: |

            # Get the line-separated list of tags
            TAGS="${{ steps.tags-metadata.outputs.tags }}"

            # Initialize an empty array
            JSON_TAGS="["
            
            # Loop through each tag and append to the JSON array
            while read -r tag; do
              JSON_TAGS+="\"$tag\","
            done <<< "$TAGS"

            # print the JSON array
            echo "TAGS=$JSON_TAGS"

            # Remove the trailing comma and close the array
            JSON_TAGS="${JSON_TAGS%,}]"
            # Output the JSON array
            echo "TAGS=$JSON_TAGS" >> $GITHUB_OUTPUT
  
    push-image:
      needs: 
        - check-image-exists
        - create-tags
      strategy:
        matrix:
          image_tags: ${{fromJson(needs.create-tags.outputs.tags)}}
      runs-on: ubuntu-latest
      steps:
        - name: Promote container images from ${{ inputs.source_registry }} to ${{ inputs.target_registry }}
          run: |
            echo "Promoting $SOURCE_IMAGE to $RELEASE_IMAGE"
            docker run --rm  \
              quay.io/skopeo/stable:latest \
              copy \
                --all \
                --retry-times 10 \
                --dest-creds "$RELEASE_CREDS" \
                --src-creds "$SOURCE_CREDS" \
                "docker://$SOURCE_IMAGE" \
                "docker://$RELEASE_IMAGE"
          env:
            SOURCE_IMAGE: "${{ inputs.source_registry }}/${{ inputs.source_image }}"
            RELEASE_IMAGE: "${{ inputs.target_registry }}/${{ inputs.target_image }}:${{ matrix.image_tags }}"
            RELEASE_CREDS: ${{ secrets.target_registry_username }}:${{ secrets.target_registry_token }}
            SOURCE_CREDS: ${{ secrets.source_registry_username }}:${{ secrets.source_registry_token }}