build_docker:
  image: gitlab.jonasled.de/jonasled/buildx-docker:latest
  stage: build
  services:
    - docker:dind
  tags:
    - docker
  before_script:
    - docker context create build
    - docker buildx create build --use
    - docker run --rm --privileged docker/binfmt:66f9012c56a8316f9244ffd7622d7c21c1f6f28d
    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
  script:
    - |
      if [[ "$CI_COMMIT_BRANCH" == "$CI_DEFAULT_BRANCH" ]]; then
        tag=""
        echo "Running on default branch '$CI_DEFAULT_BRANCH': tag = 'latest'"
      else
        tag=":$CI_COMMIT_REF_SLUG"
        echo "Running on branch '$CI_COMMIT_BRANCH': tag = $tag"
      fi
    - docker buildx build --platform linux/amd64,linux/arm,linux/arm64 --push --tag "$CI_REGISTRY_IMAGE${tag}" .
  # Run this job in a branch where a Dockerfile exists
  rules:
    - if: $CI_COMMIT_BRANCH
      exists:
        - Dockerfile