.gitlab-ci.yml

---
stages:
  - build

build:
  stage: build
  rules:
    # Build a new backend version if git tag looks like "1.2" or "1.2-something"
    - if: '$CI_COMMIT_TAG =~ /^\d+(\.\d+)*(-[-0-9A-Za-z_.]+)?$/'
  script:
    ## If $CI_COMMIT_TAG contains additional tags (e.g. "1.1-template-blah"),
    ## extract them and pass as build argument to Docker (e.g. "TAGS=template,blah")
    # - >
    #     if [[ "$CI_COMMIT_TAG" =~ ^[^-]+-.+$ ]]; then
    #       TAGS_PRE="${CI_COMMIT_TAG#*-}";
    #       TAGS="${TAGS_PRE//-/,}";
    #     else
    #       unset TAGS;
    #     fi
    ## Or, more simple approach (if you want to use in git tag
    ## some words which does not map to Go build tags)
    - TAGS=$(echo "$CI_COMMIT_TAG" | grep -qEe '-(tmpl|template)' && echo template)
    - docker build . -t "$CI_REGISTRY_IMAGE:$CI_COMMIT_TAG" "${TAGS:+--build-arg=TAGS=$TAGS}"
    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" "$CI_REGISTRY"
    - docker push "$CI_REGISTRY_IMAGE:$CI_COMMIT_TAG"