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

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OmniAuth (FREE SELF)

Users can sign in to GitLab by using their credentials from Twitter, GitHub, and other popular services. OmniAuth is the Rack framework that GitLab uses to provide this authentication.

When configured, additional sign-in options are displayed on the sign-in page.

Supported providers

GitLab supports the following OmniAuth providers.

Provider documentation	OmniAuth provider name
AliCloud	alicloud
Atlassian	atlassian_oauth2
Auth0	auth0
Authentiq	authentiq
AWS Cognito	cognito
Azure v2	azure_activedirectory_v2
Azure v1	azure_oauth2
Bitbucket Cloud	bitbucket
DingTalk	dingtalk
Facebook	facebook
Generic OAuth 2.0	oauth2_generic
GitHub	github
GitLab.com	gitlab
Google	google_oauth2
JWT	jwt
Kerberos	kerberos
OpenID Connect	openid_connect
Salesforce	salesforce
SAML	saml
Twitter	twitter

Configure initial settings

Before you configure the OmniAuth provider, configure the settings that are common for all providers.

Setting	Description	Default value
allow_single_sign_on	Enables you to list the providers that automatically create a GitLab account. The provider names are available in the OmniAuth provider name column in the supported providers table.	The default is false. If false, users must be created manually, or they can't sign in using OmniAuth.
auto_link_ldap_user	If enabled, creates an LDAP identity in GitLab for users that are created through an OmniAuth provider. You can enable this setting if you have LDAP integration enabled. Requires the uid of the user to be the same in both LDAP and the OmniAuth provider.	The default is false.
block_auto_created_users	If enabled, blocks users that are automatically created from signing in until they are approved by an administrator.	The default is true. If you set the value to false, make sure you only define providers for allow_single_sign_on that you can control, like SAML or Google. Otherwise, any user on the internet can sign in to GitLab without an administrator's approval.

To change these settings:

• For Omnibus package

  1. Open the configuration file:

     sudo editor /etc/gitlab/gitlab.rb
     

  2. Update the following section:

     # CAUTION!
     # This allows users to sign in without having a user account first. Define the allowed providers
     # using an array, for example, ["saml", "twitter"], or as true/false to allow all providers or none.
     # User accounts will be created automatically when authentication was successful.
     gitlab_rails['omniauth_allow_single_sign_on'] = ['saml', 'twitter']
     gitlab_rails['omniauth_auto_link_ldap_user'] = true
     gitlab_rails['omniauth_block_auto_created_users'] = true
     

• For installations from source

  1. Open the configuration file:

     cd /home/git/gitlab
     
     sudo -u git -H editor config/gitlab.yml
     

  2. Update the following section:

     ## OmniAuth settings
     omniauth:
       # Allow sign-in by using Twitter, Google, etc. using OmniAuth providers
       # Versions prior to 11.4 require this to be set to true
       # enabled: true
     
       # CAUTION!
       # This allows users to sign in without having a user account first. Define the allowed providers
       # using an array, for example, ["saml", "twitter"], or as true/false to allow all providers or none.
       # User accounts will be created automatically when authentication was successful.
       allow_single_sign_on: ["saml", "twitter"]
     
       auto_link_ldap_user: true
     
       # Locks down those users until they have been cleared by the admin (default: true).
       block_auto_created_users: true
     

After configuring these settings, you can configure your chosen provider.

Per-provider configuration

Introduced in GitLab 15.3.

If allow_single_sign_on is set, GitLab uses one of the following fields returned in the OmniAuth auth_hash to establish a username in GitLab for the user signing in, choosing the first that exists:

• username.
• nickname.
• email.

You can create GitLab configuration on a per-provider basis, which is supplied to the provider using args. If you set the gitlab_username_claim variable in args for a provider, you can select another claim to use for the GitLab username. The chosen claim must be unique to avoid collisions.

• For Omnibus installations

  gitlab_rails['omniauth_providers'] = [
  
    # The generic pattern for configuring a provider with name PROVIDER_NAME
  
    gitlab_rails['omniauth_providers'] = {
      name: "PROVIDER_NAME"
      ...
      args: { gitlab_username_claim: 'sub' } # For users signing in with the provider you configure, the GitLab username will be set to the "sub" received from the provider
    },
  
    # Here are examples using GitHub and Kerberos
  
    gitlab_rails['omniauth_providers'] = {
      name: "github"
      ...
      args: { gitlab_username_claim: 'name' } # For users signing in with GitHub, the GitLab username will be set to the "name" received from GitHub
    },
    {
      name: "kerberos"
      ...
      args: { gitlab_username_claim: 'uid' } # For users signing in with Kerberos, the GitLab username will be set to the "uid" received from Kerberos
    },
  ]
  

• For installations from source

  - { name: 'PROVIDER_NAME',
    ...
    args: { gitlab_username_claim: 'sub' }
  }
  - { name: 'github',
    ...
    args: { gitlab_username_claim: 'name' }
  }
  - { name: 'kerberos',
    ...
    args: { gitlab_username_claim: 'uid' }
  }
  

Passwords for users created via OmniAuth

The Generated passwords for users created through integrated authentication guide provides an overview about how GitLab generates and sets passwords for users created with OmniAuth.

Enable OmniAuth for an existing user

If you're an existing user, after your GitLab account is created, you can activate an OmniAuth provider. For example, if you originally signed in with LDAP, you can enable an OmniAuth provider like Twitter.

1. Sign in to GitLab with your GitLab credentials, LDAP, or another OmniAuth provider.
2. On the top bar, in the top right corner, select your avatar.
3. Select Edit profile.
4. On the left sidebar, select Account.
5. In the Connected Accounts section, select the OmniAuth provider, such as Twitter.
6. You are redirected to the provider. After you authorize GitLab, you are redirected back to GitLab.

You can now use your chosen OmniAuth provider to sign in to GitLab.

Enable or disable sign-in with an OmniAuth provider without disabling import sources

Administrators can enable or disable sign-in for some OmniAuth providers.

NOTE: By default, sign-in is enabled for all the OAuth providers configured in config/gitlab.yml.

To enable or disable an OmniAuth provider:

1. On the top bar, select Main menu > Admin.
2. On the left sidebar, select Settings.
3. Expand Sign-in restrictions.
4. In the Enabled OAuth authentication sources section, select or clear the checkbox for each provider you want to enable or disable.

Disable OmniAuth

OmniAuth is enabled by default. However, OmniAuth only works if providers are configured and enabled.

If OmniAuth providers are causing problems even when individually disabled, you can disable the entire OmniAuth subsystem by modifying the configuration file:

• For Omnibus installations

  gitlab_rails['omniauth_enabled'] = false
  

• For installations from source

  omniauth:
    enabled: false
  

Link existing users to OmniAuth users

Introduced in GitLab 13.4.

You can automatically link OmniAuth users with existing GitLab users if their email addresses match.

The following example enables automatic linking for the OpenID Connect provider and the Twitter OAuth provider.

• For Omnibus installations

  gitlab_rails['omniauth_auto_link_user'] = ["openid_connect", "twitter"]
  

• For installations from source

  omniauth:
    auto_link_user: ["openid_connect", "twitter"]
  

This method of enabling automatic linking works for all providers except SAML. To enable automatic linking for SAML, see the SAML setup instructions.

Create an external providers list

You can define a list of external OmniAuth providers. Users who create accounts or sign in to GitLab through the listed providers do not get access to internal projects.

To define the external providers list, use the full name of the provider, for example, google_oauth2 for Google. For provider names, see the OmniAuth provider name column in the supported providers table.

NOTE: If you remove an OmniAuth provider from the external providers list, you must manually update the users that use this sign-in method so their accounts are upgraded to full internal accounts.

• For Omnibus installations

  gitlab_rails['omniauth_external_providers'] = ['twitter', 'google_oauth2']
  

• For installations from source

  omniauth:
    external_providers: ['twitter', 'google_oauth2']
  

Use a custom OmniAuth provider

NOTE: The following information only applies to installations from source.

If you have to integrate with an authentication solution other than the OmniAuth providers included with GitLab, you can use a custom OmniAuth provider.

These steps are general. Read the OmniAuth provider's documentation for the exact implementation details.

1. Stop GitLab:

   sudo service gitlab stop
   

2. Add the gem to your Gemfile:

   gem "omniauth-your-auth-provider"
   

3. Install the new OmniAuth provider gem:

   sudo -u git -H bundle install --without development test mysql --path vendor/bundle --no-deployment
   

   These commands are the same as the commands for installing gems during initial installation, with --path vendor/bundle --no-deployment instead of --deployment.

4. Start GitLab:

   sudo service gitlab start
   

Custom OmniAuth provider examples

If you have successfully set up a provider that is not already integrated with GitLab, let us know.

We can't officially support every possible authentication mechanism available, but we'd like to at least help those with specific needs.

Keep OmniAuth user profiles up to date

You can enable profile syncing from selected OmniAuth providers. You can sync all or specific user information.

When authenticating using LDAP, the user's name and email are always synced.

• For Omnibus installations

  gitlab_rails['omniauth_sync_profile_from_provider'] = ['twitter', 'google_oauth2']
  gitlab_rails['omniauth_sync_profile_attributes'] = ['name', 'email', 'location']
  

• For installations from source

  omniauth:
    sync_profile_from_provider: ['twitter', 'google_oauth2']
    sync_profile_attributes: ['email', 'location']
  

Bypass two-factor authentication

Introduced in GitLab 12.3.

With certain OmniAuth providers, users can sign in without using two-factor authentication (2FA).

Because of a known issue users must set up 2FA on their GitLab account to bypass 2FA. Otherwise, they are prompted to set up 2FA when they sign in to GitLab.

To bypass 2FA, you can either:

• Define the allowed providers using an array (for example, ['twitter', 'google_oauth2']).
• Specify true to allow all providers, or false to allow none.

This option should be configured only for providers that already have 2FA. The default is false.

This configuration doesn't apply to SAML.

• For Omnibus package

  gitlab_rails['omniauth_allow_bypass_two_factor'] = ['twitter', 'google_oauth2']
  

• For installations from source

  omniauth:
    allow_bypass_two_factor: ['twitter', 'google_oauth2']
  

Sign in with a provider automatically

You can add the auto_sign_in_with_provider setting to your GitLab configuration to redirect login requests to your OmniAuth provider for authentication. This removes the need to select the provider before signing in.

For example, to enable automatic sign-in for the Azure v2 integration:

• For Omnibus package

  gitlab_rails['omniauth_auto_sign_in_with_provider'] = 'azure_activedirectory_v2'
  

• For installations from source

  omniauth:
    auto_sign_in_with_provider: azure_activedirectory_v2
  

Keep in mind that every sign-in attempt is redirected to the OmniAuth provider, so you can't sign in using local credentials. Ensure at least one of the OmniAuth users is an administrator.

You can also bypass automatic sign-in by browsing to https://gitlab.example.com/users/sign_in?auto_sign_in=false.

Use a custom OmniAuth provider icon

Most supported providers include a built-in icon for the rendered sign-in button.

To use your own icon, ensure your image is optimized for rendering at 64 x 64 pixels, then override the icon in one of two ways:

• Provide a custom image path:

  1. If you are hosting the image outside of your GitLab server domain, ensure your content security policies are configured to allow access to the image file.
  2. Depending on your method of installing GitLab, add a custom icon parameter to your GitLab configuration file. Read OpenID Connect OmniAuth provider for an example for the OpenID Connect provider.

• Embed an image directly in a configuration file: This example creates a Base64-encoded version of your image you can serve through a Data URL:

  1. Encode your image file with a GNU base64 command (such as base64 -w 0 <logo.png>) which returns a single-line <base64-data> string.

  2. Add the Base64-encoded data to a custom icon parameter in your GitLab configuration file:

     omniauth:
       providers:
         - { name: '...'
             icon: 'data:image/png;base64,<base64-data>'
             ...
           }
     

Change apps or configuration

Because GitLab doesn't support having multiple providers in OAuth, GitLab configuration and user identification must be updated at the same time if the provider or app is changed.

These instructions apply to all methods of authentication where GitLab stores an extern_uid and it is the only data used for user authentication.

When changing apps within a provider, if the user extern_uid does not change, only the GitLab configuration must be updated.

To swap configurations:

1. Change provider configuration in your gitlab.rb file.
2. Update extern_uid for all users that have an identity in GitLab for the previous provider.

To find the extern_uid, look at an existing user's current extern_uid for an ID that matches the appropriate field in your current provider for the same user.

There are two methods to update the extern_uid:

• Using the Users API. Pass the provider name and the new extern_uid.

• Using the Rails console:

  Identity.where(extern_uid: 'old-id').update!(extern_uid: 'new-id')`
  

Limitations

Most supported OmniAuth providers don't support Git over HTTP password authentication. As a workaround, you can authenticate using a personal access token.