CircleCI Docker Caching

config.yml

version: 2.1

default_working_dir: &working_container
  working_directory: /app
  docker:
    - image: docker:18.06.1-ce-git

default_steps:
  steps:
    - setup_remote_docker
    - restore_cache: &restore_cache
        keys:
          - v1-{{ .Branch }}
        paths:
          - /caches/app.tar
    - run: &load_cache
        name: Load Docker image layer cache
        command: |
          set +o pipefail
          docker load -i /caches/app.tar | true
          docker images

jobs:
  build:
    <<: *working_container
    steps:
      - checkout
      - setup_remote_docker
      - restore_cache: *restore_cache
      - run: *load_cache
      - run:
          name: Build application Docker image
          command: |
            docker build -t myapp-build --cache-from=myapp-build --tag myapp-build --target build .
            docker build --cache-from=myapp --cache-from=myapp-build -t myapp .
      - run: &save_layers
          name: Save Docker image layer cache
          command: |
            mkdir -p /caches
            docker save -o /caches/app.tar myapp myapp-build 
      - save_cache: &save_cache
          key: v1-{{ .Branch }}-{{ epoch }}
          paths:
            - /caches/app.tar
            - .venv
  test1:
    <<: *working_container
    steps:
      - setup_remote_docker
      - restore_cache: *restore_cache
      - run: *load_cache
      - run:
          name: Run tests
          command: |
            docker run myapp test

workflows:
  version: 2
  build-and-test:
    jobs:
      - build:
      - test1:
          requires:
            - build