If `omniauth_auto_sign_in_with_provider` is set,

it also means we're using omniauth, so we need to set it up.

config/initializers/devise.rb

@@ -219,7 +219,7 @@ Devise.setup do |config|
     end
   end
 
-  if Gitlab.config.omniauth.enabled
+  if Gitlab::OmniauthInitializer.enabled?
     Gitlab::OmniauthInitializer.new(config).execute(Gitlab.config.omniauth.providers)
   end
 end

config/initializers/omniauth.rb

@@ -17,7 +17,7 @@ OmniAuth.config.before_request_phase do |env|
   Gitlab::RequestForgeryProtection.call(env)
 end
 
-if Gitlab.config.omniauth.enabled
+if Gitlab::OmniauthInitializer.enabled?
   provider_names = Gitlab.config.omniauth.providers.map(&:name)
   Gitlab::Auth.omniauth_setup_providers(provider_names)
 end

lib/gitlab/omniauth_initializer.rb

@@ -1,5 +1,10 @@
 module Gitlab
   class OmniauthInitializer
+    def self.enabled?
+      Gitlab.config.omniauth.enabled ||
+        Gitlab.config.omniauth.auto_sign_in_with_provider.present?
+    end
+
     def initialize(devise_config)
       @devise_config = devise_config
     end