• Supported Providers
• Initial OmniAuth Configuration
• Enable OmniAuth for an Existing User
• Automatically Link Existing Users to OmniAuth Users
• Configure OmniAuth Providers as External
• Using Custom OmniAuth Providers
  • Steps
  • Examples
• Enable or disable Sign In with an OmniAuth provider without disabling import sources
• Disabling OmniAuth
• Keep OmniAuth user profiles up to date
• Bypassing two factor authentication
• Automatically sign in with provider
• Passwords for users created via OmniAuth
• Custom OmniAuth provider icon

OmniAuth

GitLab leverages OmniAuth to allow users to sign in using Twitter, GitHub, and other popular services. OmniAuth is “a generalized Rack framework for multiple-provider authentication, built on Ruby.

Configuring OmniAuth does not prevent standard GitLab authentication or LDAP (if configured) from continuing to work. Users can choose to sign in using any of the configured mechanisms.

• Initial OmniAuth Configuration
• Supported Providers
• Enable OmniAuth for an Existing User
• OmniAuth configuration sample when using Omnibus GitLab
• Enable or disable Sign In with an OmniAuth provider without disabling import sources

Supported Providers

This is a list of the current supported OmniAuth providers. Before proceeding on each provider’s documentation, make sure to first read this document as it contains some settings that are common for all providers.

Initial OmniAuth Configuration

The OmniAuth provider names from the table above are needed to configure a few global settings that are in common for all providers.

• allow_single_sign_on allows you to specify the providers that automatically create a GitLab account. For example, if you wish to enable Azure (v2) and Google, in Omnibus, specify a list of provider names:

  gitlab_rails['omniauth_allow_single_sign_on'] = ['azure_activedirectory_v2', 'google_oauth2']
  

  The value defaults to false. If false users must be created manually, or they can’t sign in by using OmniAuth.

• auto_link_ldap_user can be used if you have LDAP / ActiveDirectory integration enabled. It defaults to false. When enabled, users automatically created through an OmniAuth provider have their LDAP identity created in GitLab as well.
• block_auto_created_users defaults to true. If true auto created users will be blocked by default and must be unblocked by an administrator before they are able to sign in.

To change these settings:

• For Omnibus package

  Open the configuration file:

  sudo editor /etc/gitlab/gitlab.rb
  

  and change:

  # 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

  Open the configuration file:

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

  and change 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
  

Now we can choose one or more of the Supported Providers listed above to continue the configuration process.

Enable OmniAuth for an Existing User

Existing users can enable OmniAuth for specific providers after the account is created. For example, if the user originally signed in with LDAP, an OmniAuth provider such as Twitter can be enabled. Follow the steps below to enable an OmniAuth provider for an existing user.

1. Sign in normally - whether standard sign in, LDAP, or another OmniAuth provider.
2. In the top-right corner, select your avatar.
3. Select Edit profile.
4. In the left sidebar, select Account.
5. In the Connected Accounts section, select the desired OmniAuth provider, such as Twitter.
6. The user is redirected to the provider. After the user authorizes GitLab, they are redirected back to GitLab.

The chosen OmniAuth provider is now active and can be used to sign in to GitLab from then on.

Automatically Link Existing Users to OmniAuth Users

You can automatically link OmniAuth users with existing GitLab users if their email addresses match. For example, the following setting is used to enable the auto link feature for both a SAML provider and the Twitter OAuth provider:

For Omnibus installations

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

For installations from source

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

Configure OmniAuth Providers as External

You can define which OmniAuth providers you want to be external. Users creating accounts, or logging in by using these external providers cannot have access to internal projects. You must use the full name of the provider, like google_oauth2 for Google. Refer to the examples for the full names of the supported providers.

For Omnibus installations

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

For installations from source

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

Using Custom OmniAuth Providers

GitLab uses OmniAuth for authentication and already ships with a few providers pre-installed, such as LDAP, GitHub, and Twitter. You may also need to integrate with other authentication solutions. For these cases, you can use the OmniAuth provider.

Steps

These steps are fairly general and you must figure out the exact details from the OmniAuth provider’s documentation.

• Stop GitLab:

  sudo service gitlab stop
  

• Add the gem to your Gemfile:

  gem "omniauth-your-auth-provider"
  

• Install the new OmniAuth provider gem by running the following command:

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

  These are the same commands you used during initial installation in the Install Gems section with --path vendor/bundle --no-deployment instead of --deployment.

• Start GitLab:

  sudo service gitlab start
  

Examples

If you have successfully set up a provider that is not shipped with GitLab itself, please let us know.

While we can’t officially support every possible authentication mechanism out there, we’d like to at least help those with specific needs.

Enable or disable Sign In with an OmniAuth provider without disabling import sources

Administrators are able to enable or disable Sign In by using some OmniAuth providers.

To enable/disable an OmniAuth provider:

1. On the top bar, select Menu > Admin.
2. In the left sidebar, go to Settings.
3. Scroll to the Sign-in Restrictions section, and click Expand.

4. Below Enabled OAuth Sign-In sources, select the check box for each provider you want to enable or disable.

   

Disabling OmniAuth

Starting from version 11.4 of GitLab, OmniAuth is enabled by default. This only has an effect 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

Keep OmniAuth user profiles up to date

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

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

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']

Bypassing two factor authentication

In GitLab 12.3 or later, users can sign in with specified providers without using two factor authentication.

Define the allowed providers using an array (for example, ["twitter", 'google_oauth2']), or as true or false to allow all providers (or none). This option should be configured only for providers which already have two factor authentication (default: false). This configuration doesn’t apply to SAML.

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

For installations from source

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

Automatically sign in with provider

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 click a button before actually signing in.

For example, when using the Azure v2 integration, set the following to enable auto sign-in:

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; you can’t sign in using local credentials. Ensure at least one of the OmniAuth users has administrator permissions.

You may also bypass the auto sign in feature by browsing to https://gitlab.example.com/users/sign_in?auto_sign_in=false.

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.

Custom OmniAuth provider icon

Most supported providers include a built-in icon for the rendered sign-in button. After you ensure your image is optimized for rendering at 64 x 64 pixels, you can override this 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.
• Directly embed an image 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 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>'
             ...
           }