image: docker:stable

services:
  - docker:stable-dind

stages:
  - build
  - push

variables:
  DOCKER_DRIVER: overlay2

.reg_setup:
  before_script:
    - apk add --no-cache curl
    - curl --fail --show-error --location "https://github.com/genuinetools/reg/releases/download/v$REG_VERSION/reg-linux-amd64" --output /usr/local/bin/reg
    - echo "$REG_SHA256  /usr/local/bin/reg" | sha256sum -c -
    - chmod a+x /usr/local/bin/reg
  variables:
    REG_SHA256: ade837fc5224acd8c34732bf54a94f579b47851cc6a7fd5899a98386b782e228
    REG_VERSION: 0.16.1

build_image:
  script:
    - docker login -u gitlab-ci-token -p $CI_JOB_TOKEN $CI_REGISTRY
    - docker build -t $INTERMEDIATE_IMAGE_TAG .
    - docker push $INTERMEDIATE_IMAGE_TAG
  stage: build
  tags:
    - docker
  variables:
    INTERMEDIATE_IMAGE_TAG: $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA

push_master:
  extends:
    - .reg_setup
  only:
    - master
  script:
    - docker login -u gitlab-ci-token -p $CI_JOB_TOKEN $CI_REGISTRY
    - docker pull $INTERMEDIATE_IMAGE_TAG
    - /usr/local/bin/reg rm -d --auth-url $CI_REGISTRY -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $INTERMEDIATE_IMAGE_TAG
    - docker tag $INTERMEDIATE_IMAGE_TAG $IMAGE_TAG
    - docker push $IMAGE_TAG
  stage: push
  tags:
    - docker
  variables:
    IMAGE_TAG: $CI_REGISTRY_IMAGE:latest
    INTERMEDIATE_IMAGE_TAG: $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA

push_other:
  extends:
    - .reg_setup
  except:
    - master
  only:
    - branches
    - tags
  script:
    - docker login -u gitlab-ci-token -p $CI_JOB_TOKEN $CI_REGISTRY
    - docker pull $INTERMEDIATE_IMAGE_TAG
    - /usr/local/bin/reg rm -d --auth-url $CI_REGISTRY -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $INTERMEDIATE_IMAGE_TAG
    - docker tag $INTERMEDIATE_IMAGE_TAG $IMAGE_TAG
    - docker push $IMAGE_TAG
  stage: push
  tags:
    - docker
  variables:
    IMAGE_TAG: $CI_REGISTRY_IMAGE:CI_COMMIT_REF_NAME
    INTERMEDIATE_IMAGE_TAG: $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA