config.yaml

version: 2
jobs:
  build_docker:
    docker:
      - image: docker:18.09-git
    working_directory: /build
    steps:
      - checkout
      - setup_remote_docker: 
          docker_layer_caching: true
      - run:
          name: Docker login to registry
          command: |
            docker login -u $docker_user -p $docker_password hub.docker.com
      - run:
          name: Build docker image and push to registry
          command: |
            echo 'export GIT_HASH=`echo $CIRCLE_SHA1 | head -c 8`' >> $BASH_ENV
            source $BASH_ENV
            docker build . -t some-docker-account/some-docker-image:$GIT_HASH
            docker push some-docker-account/some-docker-image:$GIT_HASH

  release_docker:
    docker:
      - image: docker:18.09-git
    working_directory: /build
    steps:
      - setup_remote_docker: 
          docker_layer_caching: true
      - run:
          name: Docker login to registry
          command: |
            docker login -u $docker_user -p $docker_password hub.docker.com
      - run:
          name: Re-tag docker image
          command: |
            echo 'export GIT_HASH=`echo $CIRCLE_SHA1 | head -c 8`' >> $BASH_ENV
            source $BASH_ENV
            docker pull some-docker-account/some-docker-image:$GIT_HASH
            docker tag some-docker-account/some-docker-image:$GIT_HASH some-docker-account/some-docker-image:$CIRCLE_TAG
            docker push some-docker-account/some-docker-image:$CIRCLE_TAG

workflows:
  version: 2
  default:
    jobs:
      - checkout:
          filters:
            tags:
              ignore: /[0-9]+(\.[0-9]+)*/
      - build_docker
      
  create_release:
    jobs:
      - release_docker:
          filters:
            # Ignore any commit on any branch by default
            branches:
              ignore: /.*/
            # Only act on semver tags
            tags:
              only: /^[0-9]+(\.[0-9]+)*$/