Update .gitlab-ci.yml

.gitlab-ci.yml

@@ -29,6 +29,7 @@ review:start:
         - sudo docker run --detach --rm --env VIRTUAL_HOST=${CI_ENVIRONMENT_SLUG} --name ${DOCKER_CONTAINER_NAME} ${REVIEW_IMAGE}:development || true
         - sudo docker cp . ${DOCKER_CONTAINER_NAME}:/opt/app
         - sudo docker exec ${DOCKER_CONTAINER_NAME} gitbook install
+        - nc -zv ${CI_ENVIRONMENT_SLUG}.collaborating.tuhh.de 80
     environment:
         name: review/${CI_COMMIT_REF_NAME}
         url: http://${CI_ENVIRONMENT_SLUG}.collaborating.tuhh.de