# OmniAuth

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](#initial-omniauth-configuration)
+ [Supported Providers](#supported-providers)
+ [Enable OmniAuth for an Existing User](#enable-omniauth-for-an-existing-user)

### Initial OmniAuth Configuration

Before configuring individual OmniAuth providers there are a few global settings that need to be verified.

1. Open the configuration file<br />

    ```sh
    cd /home/git/gitlab

    sudo -u git -H editor config/gitlab.yml
    ```

2. Find the section dealing with OmniAuth. The section will look similar to the following.<br />

    ```
      ## OmniAuth settings
      omniauth:
        # Allow login via Twitter, Google, etc. using OmniAuth providers
        enabled: false

        # CAUTION!
        # This allows users to login without having a user account first (default: false).
        # User accounts will be created automatically when authentication was successful.
        allow_single_sign_on: false
        # Locks down those users until they have been cleared by the admin (default: true).
        block_auto_created_users: true

        ## Auth providers
        # Uncomment the following lines and fill in the data of the auth provider you want to use
        # If your favorite auth provider is not listed you can use others:
        # see https://github.com/gitlabhq/gitlab-public-wiki/wiki/Custom-omniauth-provider-configurations
        # The 'app_id' and 'app_secret' parameters are always passed as the first two
        # arguments, followed by optional 'args' which can be either a hash or an array.
        providers:
        # - { name: 'google_oauth2', app_id: 'YOUR APP ID',
        #     app_secret: 'YOUR APP SECRET',
        #     args: { access_type: 'offline', approval_prompt: '' } }
        # - { name: 'twitter', app_id: 'YOUR APP ID',
        #     app_secret: 'YOUR APP SECRET'}
        # - { name: 'github', app_id: 'YOUR APP ID',
        #     app_secret: 'YOUR APP SECRET',
        #     args: { scope: 'user:email' } }
    ```

3. Change `enabled` to `true`.
4. Consider the next two configuration options: `allow_single_sign_on` and `block_auto_created_users`.
    * `allow_single_sign_on` defaults to `false`. If `false` users must be created manually or they will not be able to
    sign in via OmniAuth.
    * `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 `allow_single_sign_on` to `true` and `block_auto_created_users` to `false` please be aware
    that any user on the Internet will be able to successfully sign in to your GitLab without administrative approval.
5. Choose one or more of the Supported Providers below to continue configuration.

### Supported Providers

+ [GitHub](github.md)
+ [Google](google.md)
+ [Twitter](twitter.md)

### 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. Go to profile settings (the silhouette icon in the top right corner).
3. Select the "Account" tab.
4. Under "Social Accounts" select the desired OmniAuth provider, such as Twitter.
5. 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.
