.gitlab-ci.yml

# This job was creatin using the template from:
# https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/ci/templates/Docker.gitlab-ci.yml

# Build a Docker image with CI/CD and push to the GitLab registry.
# Docker-in-Docker documentation: https://docs.gitlab.com/ee/ci/docker/using_docker_build.html
#
# A new image should be created each time there is a new tag added to the repo
# This should save some time in the pipelines, and also avoid rebuilding the image
# when unnecessary, e.g. if the only thing updated was the README.md

docker-build:
  # Use the official docker image.
  image: docker:latest
  stage: build
  services:
    - docker:dind
  before_script:
    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
  # Default branch leaves tag empty (= latest tag)
  # All other branches are tagged with the escaped branch name (commit ref slug)
  script:
    # Name the image using the git tag
    - tag=$(git describe --abbrev=0 2>/dev/null || echo '')
    - docker build --pull -t "$CI_REGISTRY_IMAGE${tag}" .
    - docker push "$CI_REGISTRY_IMAGE${tag}"
  # Only create a new image when a commit is tagged
  only:
    refs:
      - tags