GitLab CI officially supports (recent versions of) these Linux distributions:
* Ubuntu Linux
* Debian/GNU Linux
* CentOS
* RedHat Enterprise Linux (please use the CentOS packages and instructions)
* Scientific Linux (please use the CentOS packages and instructions)
* Oracle Linux (please use the CentOS packages and instructions)
Additionally GitLab CI requires:
* GitLab 7.7+ (to host the repositories you test)
* ruby 2.1.5
* MySQL or PostgreSQL
Hardware requirements:
* 1GB of memory or more is recommended, 512MB works
* 2 CPU cores or more are recommended, 1 CPU core works
* A little disk space, 100MB or less
## Features
* Single Sign On: use the same login and password as on your GitLab instance
* Quick project setup: add your project in a single click, all setup automatic via the GitLab API
* Elegant and flexible: build scripts are written in bash, test projects in any programming language
* Merge request integration: see the status of the feature branch build within the Merge Request
* Distributed by default: GitLab CI and build runners can run on separate machines providing more stability
* Realtime logging: the current build log scrolls and updates every few seconds
* Parallel builds: split a build over multiple runners so it executes quickly
### Installation
*[Omnibus packages](https://about.gitlab.com/downloads/)(recommended) now include the CI coordinator, see the [configuration instructions](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/doc/gitlab-ci/README.md)
*[Unofficial Docker Image by Sameer Naik](https://github.com/sameersbn/docker-gitlab-ci)
*[Unofficial Docker Image by Anastas Dancha](https://registry.hub.docker.com/u/anapsix/gitlab-ci/) is available via `docker pull anapsix/gitlab-ci`
*[GitLab Development Kit](https://gitlab.com/gitlab-org/gitlab-development-kit) is recommended for development work.
### GitLab Runner
To perform the actual build you need to install GitLab Runner.
The the next section about Architecture to understand what a runner does.
*[GitLab Runner Omnibus package for Linux](https://gitlab.com/gitlab-org/omnibus-gitlab-runner/blob/master/doc/install/README.md) This is the recommended way to install GitLab Runner.
*[GitLab Runner source code for Linux](https://gitlab.com/gitlab-org/gitlab-ci-runner)
*[Unofficial GitLab Runner for Windows](https://github.com/virtualmarc/gitlab-ci-runner-win)
*[Unofficial GitLab Runner for Scala/Java](https://github.com/nafg/gitlab-ci-runner-scala)
*[Unofficial GitLab Runner for Node](https://www.npmjs.org/package/gcr)
### Architecture
__GitLab CI__ is a web application with an API that stores its state in a databse.
It manages projects/builds and provides a nice user interface.
It uses the GitLab application API to authenticate users.
[GitLab Runner](https://github.com/gitlabhq/gitlab-ci-runner) is a pure ruby application which processes builds.
It can be deployed separately and works with GitLab CI through an API.
In order to run tests you need at least 1 __GitLab CI__ instance and 1 __GitLab Runner__.
However, for running several builds at the same time you may want to setup more than one __GitLab Runner__.
Possible Cases:
* 1 __GitLab CI__ and N __GitLab CI Runner__ instances on same machine
* 1 __GitLab CI__ and N __GitLab CI Runner__ instances on different machines
* 1 __GitLab CI__ and N __GitLab CI Runner__ instances on local machines
