build:
  image: docker:cli
  stage: build
  services:
    - docker:dind
  variables:
    DOCKER_IMAGE_NAME: $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG
  before_script:
    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
  script:
    - |
        docker build -t "$DOCKER_IMAGE_NAME" .
        docker tag "$DOCKER_IMAGE_NAME" "$CI_REGISTRY_IMAGE:main"
        docker push "$CI_REGISTRY_IMAGE:main"