GitLab as OpenID Connect identity provider

This document is about using GitLab as an OpenID Connect identity provider to sign in to other services.

Introduction to OpenID Connect

OpenID Connect (OIC) is a simple identity layer on top of the OAuth 2.0 protocol. It allows clients to verify the identity of the end-user based on the authentication performed by GitLab, as well as to obtain basic profile information about the end-user in an interoperable and REST-like manner. OIC performs many of the same tasks as OpenID 2.0, but does so in a way that is API-friendly, and usable by native and mobile applications.

On the client side, you can use omniauth-openid-connect for Rails applications, or any of the other available client implementations.

GitLab's implementation uses the doorkeeper-openid_connect gem, refer to its README for more details about which parts of the specifications are supported.

Enabling OpenID Connect for OAuth applications

Refer to the OAuth guide for basic information on how to set up OAuth applications in GitLab. To enable OIC for an application, all you have to do is select the openid scope in the application settings.

Currently the following user information is shared with clients:

Claim	Type	Description
sub	string	An opaque token that uniquely identifies the user
auth_time	integer	The timestamp for the user's last authentication
name	string	The user's full name
nickname	string	The user's GitLab username
email	string	The user's public email address
email_verified	boolean	Whether the user's public email address was verified
website	string	URL for the user's website
profile	string	URL for the user's GitLab profile
picture	string	URL for the user's GitLab avatar