GitLab Container Registry is a secure and private registry for Docker images integrated completely in Gitlab. In this tutorial we will setup and use GitLab Container Registry. If you're using previous versions of Gitlab upgrade and then follow this tutorial.

SSL Certificate - Eventhough docker may support unsecured private registries(self signed SSL Certifcates and http registy URL's). GitLab seems to accept only "https" in url of registry. as when i tried to use http in URL it throw me the following error

RuntimeError
  ------------
  Unsupported GitLab Registry external URL scheme: http

you can use self signed certificates or use letsencypt's certbot(which is opensource certyfing tool).

Using Certbot

To use certbot stop any webservers you may be runnng(like nginx, apache). Ensure DNS Mapping is pointing to correct server and run following commands

git clone https://github.com/certbot/certbot
cd certbot
./certbot-auto certonly --standalone -d <domain-name>

you will be asked to enter an email for identity and recovery and your cert and key will be available in 

certificate -  /etc/letsencrypt/live/<domain-name>/fullchain.pem;
certificate_key - /etc/letsencrypt/live/<domain-name>/privkey.pem;

Modifying /etc/gitlab/gitlab.rb file:

registry_external_url 'https://<domain/sub-domain name>'
registry_nginx['ssl_certificate'] = <location-to-certificate>
registry_nginx['ssl_certificate_key'] = <location-to-certificate-key>

Reconfigure GitLab

sudo gitlab-ctl reconfigure

Then under every Project Menu will have a Tab "Container Registry" which points to Projects Docker Image Container.