GitLab supports many convenient features on top of Git. It's a large and complex software system based on Ruby. As such, it can be difficult to install, what with getting all the dependencies right and so on.
There is a nice Docker Compose file for GitLab available at https://registry.hub.docker.com/u/sameersbn/gitlab/. If you followed the instructions for Docker shown previously, including the installation of docker-compose, it's now pretty simple to start a local GitLab instance:
mkdir gitlab
cd gitlab
wget https://raw.githubusercontent.com/sameersbn/docker-gitlab/master/docker-compose.yml
docker-compose up
The docker-compose command will read the .yml file and start all the required services in a default demonstration configuration.
If you read the start up log in the console window, you will notice that three separate application containers have been started...