GitLab as OpenID Connect identity provider (FREE)

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

Introduction to OpenID Connect

OpenID Connect (OIDC) 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.
Obtain basic profile information about the end-user in an interoperable and REST-like manner.

OIDC performs many of the same tasks as OpenID 2.0, but is API-friendly and usable by native and mobile applications.

On the client side, you can use OmniAuth::OpenIDConnect for Rails applications, or any of the other available client implementations.

The GitLab 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 OIDC for an application, all you have to do is select the openid scope in the application settings.

Settings discovery

If your client allows importing OIDC settings from a discovery URL, you can use the following URL to automatically find the correct settings for GitLab.com:

https://gitlab.com/.well-known/openid-configuration

Similar URLs can be used for other GitLab instances.

Shared information

The following user information is shared with clients:

Claim	Type	Description
`sub`	`string`	The ID of 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
`preferred_username`	`string`	The user's GitLab username
`email`	`string`	The user's email address This is the user's primary email address if the application has access to the `email` claim and the user's public email address otherwise
`email_verified`	`boolean`	Whether the user's 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
`groups`	`array`	Paths for the groups the user is a member of, either directly or through an ancestor group.
`groups_direct`	`array`	Paths for the groups the user is a direct member of.
`https://gitlab.org/claims/groups/owner`	`array`	Names of the groups the user is a direct member of with Owner role
`https://gitlab.org/claims/groups/maintainer`	`array`	Names of the groups the user is a direct member of with Maintainer role
`https://gitlab.org/claims/groups/developer`	`array`	Names of the groups the user is a direct member of with Developer role

The claims sub, sub_legacy, email, email_verified and groups_direct are included in the ID token. All other claims are available from the /oauth/userinfo endpoint used by OIDC clients.