Silly…

# This file is a template, and might need editing before it works on your project.

docker-build-master:

  # Official docker image.

  image: docker:latest

  stage: build

  services:

    - docker:dind

  before_script:

    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY

  script:

    - docker build --pull -t "$CI_REGISTRY_IMAGE" .

    - docker push "$CI_REGISTRY_IMAGE"

  only:

    - master

docker-build:

  # Official docker image.

  image: docker:latest

  stage: build

  services:

    - docker:dind

  before_script:

    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY

  script:

    - docker build --pull -t "$CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG" .

    - docker push "$CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG"

  except:

    - master