GitLab leverages OmniAuth to allow users to sign in using Twitter, GitHub, and other popular services.

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

Before configuring individual OmniAuth providers there are a few global settings that are in common for all providers that we need to consider.

Omniauth needs to be enabled, see details below for example.
allow_single_sign_on allows you to specify the providers you want to allow to automatically create an account. It defaults to false. If false users must be created manually or they will not be able to sign in via 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 OmniAuth will be linked to their LDAP entry as well.
block_auto_created_users defaults to true. If true auto created users will be blocked by default and will have to be unblocked by an administrator before they are able to sign in.

Note: If you set block_auto_created_users to false, make sure to only define providers under allow_single_sign_on that you are able to control, like SAML, Shibboleth, Crowd or Google, or set it to false otherwise any user on the Internet will be able to successfully sign in to your GitLab without administrative approval.

Note: auto_link_ldap_user requires the uid of the user to be the same in both LDAP and the OmniAuth provider.

To change these settings:

For omnibus package

Open the configuration file:

sudo editor /etc/gitlab/gitlab.rb

and change:

gitlab_rails['omniauth_enabled'] = true

# CAUTION!
# This allows users to login without having a user account first. Define the allowed providers
# using an array, e.g. ["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 login via Twitter, Google, etc. using OmniAuth providers
    enabled: true

    # CAUTION!
    # This allows users to login without having a user account first. Define the allowed providers
    # using an array, e.g. ["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.

Sign in normally - whether standard sign in, LDAP, or another OmniAuth provider.
Go to profile settings (the silhouette icon in the top right corner).
Select the "Account" tab.
Under "Connected Accounts" select the desired OmniAuth provider, such as Twitter.
The user will be redirected to the provider. Once the user authorized GitLab they will be redirected back to GitLab.

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

Configure OmniAuth Providers as External

Note: This setting was introduced with version 8.7 of GitLab

You can define which OmniAuth providers you want to be external so that all users creating accounts, or logging in via these providers will not be able to have access to internal projects. You will need to use the full name of the provider, like google_oauth2 for Google. Refer to the examples for the full names of the supported providers.

Note: If you decide to remove an OmniAuth provider from the external providers list you will need to manually update the users that use this method to login, if you want their accounts to be 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']

Using Custom Omniauth Providers

Note: The following information only applies for installations from source.

GitLab uses Omniauth for authentication and already ships with a few providers pre-installed (e.g. LDAP, GitHub, Twitter). But sometimes that is not enough and you need to integrate with other authentication solutions. For these cases you can use the Omniauth provider.

Steps

These steps are fairly general and you will need to 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"
```

If you're using MySQL, install the new Omniauth provider gem by running the following command:

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

If you're using PostgreSQL, 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 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.

You can help others by reporting successful configurations and probably share a few insights or provide warnings for common errors or pitfalls by sharing your experience in the public Wiki.

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

Note: This setting was introduced with version 8.8 of GitLab.

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

Note: By default Sign In is enabled via all the OAuth Providers that have been configured in config/gitlab.yml.

In order to enable/disable an OmniAuth provider, go to Admin Area -> Settings -> Sign-in Restrictions section -> Enabled OAuth Sign-In sources and select the providers you want to enable or disable.

Enabled OAuth Sign-In sources