image: docker:20.10.5

stages:
  - build
  - push

before_script:
  - echo -n $CI_REGISTRY_TOKEN | docker login -u "$CI_REGISTRY_USER" --password-stdin $CI_REGISTRY

build:
  stage: build
  tags:
    - docker
  script:
    - docker pull $CI_REGISTRY_IMAGE:latest || true
    - docker build --cache-from $CI_REGISTRY_IMAGE:latest --tag $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA .
    - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA

# Tag the "master" branch as "latest"
push latest:
  stage: push
  tags:
    - docker
  script:
    - docker pull $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA
    - docker tag $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA $CI_REGISTRY_IMAGE:latest
    - docker push $CI_REGISTRY_IMAGE:latest
  only:
    - master

# Docker tag any Git tag
push tag:
  stage: push
  tags:
    - docker
  only:
    - tags
  script:
    - docker pull $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA
    - docker tag $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG
    - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG