This is a short summary of the GitLab guide on Install a GitLab CE Omnibus package.
Requirements
In order to install the GitLab Community Edition on your server, you should read the requirements page. To make it brief, the recommended requirements are:
Installation
The recommended method is to install the Omnibus package, which is fast to install. It contains GitLab and all its dependencies (Ruby, PostgreSQL, Redis, Nginx, Unicorn, etc.). For other methods check out the GitLab's installation options
With Ubuntu 16.04 as the recommended OS, this guide describes the installation steps on Debian based distributions. For CentOS, RHEL, Oracle Linux and Scientific Linux, please refer to the original guides:
Ubuntu, Debian, Raspberrian
Install necessary dependencies. If you use Postfix select 'Internet Site' during setup
sudo apt-get install curl openssh-server ca-certificates postfix apt-transport-https
curl https://packages.gitlab.com/gpg.key | sudo apt-key add -
Add the Gitlab package server and install the package
sudo curl -sS https://packages.gitlab.com/install/repositories/gitlab/raspberry-pi2/script.deb.sh | sudo bash
sudo apt-get install gitlab-ce
If you do not want to install the repository through a piped script, download the package manually and install it using
dpkg -i gitlab-ce_<version>.deb
Now configure and start GitLab
sudo gitlab-ctl reconfigure
Finally browse to the hostname and login. At first you will be redirected to provide a password for the initial administrator account. After that you're able to login in. The default administrator account username is root.