Update .gitlab-ci.yml file

# To contribute improvements to CI/CD templates, please follow the Development guide at:

# https://docs.gitlab.com/ee/development/cicd/templates.html

# This specific template is located at:

# 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

#

# This template uses one generic job with conditional builds

# for the default branch and all other (MR) branches.

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:

    - |

      docker build -t "$CI_REGISTRY_IMAGE${tag}" .

      docker push "$CI_REGISTRY_IMAGE${tag}"