Keep GitLab environment running in Docker container

I'm aiming to deploy an environment for testing. It's a PHP application, and I could simply serve the PHP files using the embedded server.

My .gitlab-ci.yml is plain simple:

docker_test:
  stage: deploy
  image: php:7.2
  rules:
    - if: $CI_PIPELINE_SOURCE == "merge_request_event"
  environment:
    name: development/$CI_MERGE_REQUEST_SOURCE_BRANCH_NAME
    url: $CI_SERVER_PROTOCOL://$CI_SERVER_HOST:8000/$CI_PROJECT_PATH_SLUG/$CI_ENVIRONMENT_SLUG:8000
    auto_stop_in: 1 hour
  script:
    - php -S 0.0.0.0:8000 -t /builds/$CI_PROJECT_PATH

What I want is: When pipeline runs, the environment will be live, the container should be up and running, and a tester should be able to access it using the URL. After one hour, or if Stop button is pressed, environment shoud stop and Docker container stopped and removed. However, I don't figure out yet, how to keep the container running in the background. When pipeline is executed, it freezes on the script, and when it's cancelled, Docker container is stopped.

Any idea on how to achieve this?

Seems docker runners won't allow this easily. I just changed to a shell executor that runs the required docker commands for start and stop:

docker_test:
  stage: deploy
  rules:
    - if: $CI_PIPELINE_SOURCE == "merge_request_event"
  environment:
    name: development/$CI_MERGE_REQUEST_SOURCE_BRANCH_NAME
    url: $CI_SERVER_PROTOCOL://$CI_SERVER_HOST:8000/$CI_PROJECT_NAME/$CI_ENVIRONMENT_SLUG:8000
    auto_stop_in: 1 hour
  script: docker run --name $CI_MERGE_REQUEST_SOURCE_BRANCH_NAME --rm -dt -v $CI_PROJECT_DIR:/app:Z -p 8000:8000 php:7.2 php -S 0.0.0.0:8000 -t /app

stop_docker_test:
  stage: deploy
  rules:
    - if: $CI_PIPELINE_SOURCE == "merge_request_event"
  environment:
    name: development/$CI_MERGE_REQUEST_SOURCE_BRANCH_NAME
    action: stop
  when: manual
  script: docker stop $CI_MERGE_REQUEST_SOURCE_BRANCH_NAME