You can observe the status of your gitlab-web instance with
docker-compose ps
docker logs -f gitlab-web
If you run into configuration troubles you need to enter the container to make changes to the gitlab.rb file and call gitlab reconfigure
docker container exec -it gitlab-web /bin/bash
$ vi /etc/gitlab/gitlab.rb
Exit the container (CTRL+D) and check the logs with
docker logs gitlab-web
Pay attention the fix to gitlab.rb is not permanent, reconfigure or restart the container will remove your change and you have to do it again. You need to put the correct configuration into the dockerfile at GITLAB_OMNIBUS_CONFIG