Bladegreat

build-container:
  stage: build
  rules:
    - if: '$CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH'
      variables:
        image_tag: "$CI_REGISTRY_IMAGE"
      changes:
        - Dockerfile
    - if: '$CI_COMMIT_BRANCH != $CI_DEFAULT_BRANCH'
      variables:
        image_tag: "$CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG"
      changes:
        - Dockerfile
  services:
    - docker:18-dind
  before_script:
    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
  script:
    - docker build --pull -t ${image_tag} .
    - docker push ${image_tag}