A typical install of GitLab will be on RHEL or Ubuntu Linux. It uses Apache or nginx as a web front end to proxypass the Unicorn web server. Communication between Unicorn and the front end is usually HTTP but access via socket is also supported. The web front end accesses `~git/gitlab/public` bypassing the Unicorn server to serve static pages, attachments, and other resources the GitLab core creates (such as uploaded avatars or archives). GitLab serves web pages and a [GitLab API](https://gitlab.com/gitlab-org/gitlab-ce/tree/master/doc/api) using the Unicorn web server. It uses Sidekiq as a job queue which, in turn, uses redis as a non-persistent database backend for job information, meta data, and incomming jobs. The GitLab web app uses MySQL or PostgreSQL for persistent database information (e.g. users, permissions, issues, other meta data). GitLab stores the bare git repositories it serves in `~git/repositories` by default. It also keeps default branch and hook information with the bare repository. GitLab maintains a checked out version of each repository in `~git/gitlab-satellites`. The satellite repository is used by the web interface for editing repositories and the wiki which is also a git repository. When serving repositories over HTTP/HTTPS GitLab utilizes the GitLab API to resolve authorization and access as well as serving git objects.
A typical install of GitLab will be on RHEL or Ubuntu Linux. It uses Apache or nginx as a web front end to proxypass the Unicorn web server. Communication between Unicorn and the front end is usually HTTP but access via socket is also supported. The web front end accesses `~git/gitlab/public` bypassing the Unicorn server to serve static pages, uploads (e.g. avatar images or attachments), and precompiled assets. GitLab serves web pages and a [GitLab API](https://gitlab.com/gitlab-org/gitlab-ce/tree/master/doc/api) using the Unicorn web server. It uses Sidekiq as a job queue which, in turn, uses redis as a non-persistent database backend for job information, meta data, and incomming jobs. The GitLab web app uses MySQL or PostgreSQL for persistent database information (e.g. users, permissions, issues, other meta data). GitLab stores the bare git repositories it serves in `~git/repositories` by default. It also keeps default branch and hook information with the bare repository. GitLab maintains a checked out version of each repository in `~git/gitlab-satellites`. The satellite repository is used by the web interface for editing repositories and the wiki which is also a git repository. When serving repositories over HTTP/HTTPS GitLab utilizes the GitLab API to resolve authorization and access as well as serving git objects.
The add-on component gitlab-shell serves repositories over SSH. It manages the SSH keys within `~git/.ssh/authorized_keys` which should not be manually edited. gitlab-shell accesses the bare repositories directly to serve git objects and communicates with redis to submit jobs to Sidekiq for GitLab to process. gitlab-shell queries the GitLab API to determine authorization and access.
