.gitlab-ci.yml

# This is the tag of the docker image used for the build jobs. If the
# image doesn't exist yet, the containers-build stage generates it.
#
# In order to generate a new image, one should generally change the tag.
# While removing the image from the registry would also work, that's not
# recommended except for ephemeral images during development: Replacing
# an image after a significant amount of time might pull in newer
# versions of gcc/clang or other packages, which might break the build
# with older commits using the same tag.
#
# After merging a change resulting in generating a new image to the
# main repository, it's recommended to remove the image from the source
# repository's container registry, so that the image from the main
# repository's registry will be used there as well.
#
# The format of the tag is "%Y-%m-%d-${counter}" where ${counter} stays
# at "01" unless you have multiple updates on the same day :)
variables:
  UBUNTU_TAG: 2019-01-31-01
  UBUNTU_IMAGE: "$CI_REGISTRY/$CI_PROJECT_PATH/ubuntu:$UBUNTU_TAG"


stages:
  - containers-build


# CONTAINERS

containers:ubuntu:
  stage: containers-build
  image: docker:stable
  services:
    - docker:dind
  variables:
    DOCKER_HOST: tcp://docker:2375
    DOCKER_DRIVER: overlay2
  script:
    # Enable experimental features such as `docker manifest inspect`
    - mkdir -p ~/.docker
    - "echo '{\"experimental\": \"enabled\"}' > ~/.docker/config.json"
    - docker login -u gitlab-ci-token -p $CI_JOB_TOKEN $CI_REGISTRY
    # Check if the image (with the specific tag) already exists
    - docker manifest inspect $UBUNTU_IMAGE && exit || true
    - docker build -t $UBUNTU_IMAGE -f .gitlab-ci/Dockerfile.ubuntu .
    - docker push $UBUNTU_IMAGE
  only:
    changes:
      - .gitlab-ci.yml
      - .gitlab-ci/Dockerfile.ubuntu