The official containers from GitLab use the omnibus-gitlab package, so all the configuration is managed through the unique configuration file, /etc/gitlab/gitlab.rb.
Once the container is started, you can connect to it by starting a Bash session:
docker exec -it gitlab /bin/bash
You can now edit /etc/gitlab/gitlab.rb inside the Docker container. Then you can run gitlab-ctl reconfigure after that to apply the changes.
A second way to configure the container is to start it up with a environment variable, GITLAB_OMNIBUS_CONFIG. This variable can contain the contents of a gitlab.rb file. These settings will not be persisted to the real file.
You could use the following code:
sudo docker run \
--hostname gitlab.joustie.nl \
--env GITLAB_OMNIBUS_CONFIG="external_url 'http://gitlab.joustie.nl/'; gitlab_rails['lfs_enabled&apos...