debian-mirror-gitlab/doc/integration/oauth_provider.md

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GitLab as OAuth2 authentication service provider

This document describes how you can use GitLab as an OAuth 2 authentication service provider.

If you want to use:

• The OAuth2 protocol to access GitLab resources on user's behalf, see OAuth2 provider.
• Other OAuth 2 authentication service providers to sign in to GitLab, see the OAuth2 client documentation.
• The related API, see Applications API.

Introduction to OAuth

OAuth 2 provides to client applications a 'secure delegated access' to server resources on behalf of a resource owner. OAuth 2 allows authorization servers to issue access tokens to third-party clients with the approval of the resource owner or the end-user.

OAuth 2 can be used:

• To allow users to sign in to your application with their GitLab.com account.
• To set up GitLab.com for authentication to your GitLab instance. (see GitLab OmniAuth).

The 'GitLab Importer' feature also uses OAuth 2 to give access to repositories without sharing user credentials to your GitLab.com account.

GitLab supports several ways of adding a new OAuth 2 application to an instance:

• User owned applications
• Group owned applications
• Instance-wide applications

The only difference between these methods is the permission levels. The default callback URL is http://your-gitlab.example.com/users/auth/gitlab/callback.

User owned applications

To add a new application for your user:

1. In the top-right corner, select your avatar.

2. Select Edit profile.

3. In the left sidebar, select Applications.

4. Enter a Name, Redirect URI and OAuth 2 scopes as defined in Authorized Applications. The Redirect URI is the URL where users are sent after they authorize with GitLab.

5. Select Save application. GitLab displays:

   • Application ID: OAuth 2 Client ID.
   • Secret: OAuth 2 Client Secret.

Group owned applications

Introduced in GitLab 13.11.

To add a new application for a group:

1. Navigate to the desired group.

2. In the left sidebar, select Settings > Applications.

3. Enter a Name, Redirect URI and OAuth 2 scopes as defined in Authorized Applications. The Redirect URI is the URL where users are sent after they authorize with GitLab.

4. Select Save application. GitLab displays:

   • Application ID: OAuth 2 Client ID.
   • Secret: OAuth 2 Client Secret.

Instance-wide applications

To create an application for your GitLab instance, select Admin Area > Applications > New application.

When creating an Admin Area application, you can mark it as trusted. The user authorization step is automatically skipped for this application.

Authorized applications

Every application you authorize with your GitLab credentials is shown in the Authorized applications section under Settings > Applications.

The GitLab OAuth 2 applications support scopes, which allow various actions that any given application can perform. Available scopes are depicted in the following table.

Scope	Description
api	Grants complete read/write access to the API, including all groups and projects, the container registry, and the package registry.
read_user	Grants read-only access to the authenticated user's profile through the /user API endpoint, which includes username, public email, and full name. Also grants access to read-only API endpoints under /users.
read_api	Grants read access to the API, including all groups and projects, the container registry, and the package registry.
read_repository	Grants read-only access to repositories on private projects using Git-over-HTTP or the Repository Files API.
write_repository	Grants read-write access to repositories on private projects using Git-over-HTTP (not using the API).
read_registry	Grants read-only access to container registry images on private projects.
write_registry	Grants read-only access to container registry images on private projects.
sudo	Grants permission to perform API actions as any user in the system, when authenticated as an administrator user.
openid	Grants permission to authenticate with GitLab using OpenID Connect. Also gives read-only access to the user's profile and group memberships.
profile	Grants read-only access to the user's profile data using OpenID Connect.
email	Grants read-only access to the user's primary email address using OpenID Connect.

At any time you can revoke any access by clicking Revoke.