Introduce Gitlab::Auth.omniauth_setup_providers

Which could extend from EE

config/initializers/omniauth.rb

@@ -19,10 +19,5 @@ end
 
 if Gitlab.config.omniauth.enabled
   provider_names = Gitlab.config.omniauth.providers.map(&:name)
-  require 'omniauth-kerberos' if provider_names.include?('kerberos')
-  require_dependency 'omni_auth/strategies/kerberos_spnego' if provider_names.include?('kerberos_spnego')
-
-  if provider_names.include?('group_saml')
-    OmniAuth.config.on_failure = ::Gitlab::Auth::GroupSaml::FailureHandler.new(OmniAuth.config.on_failure)
-  end
+  Gitlab::Auth.omniauth_setup_providers(provider_names)
 end

ee/lib/ee/gitlab/auth.rb

 module EE
   module Gitlab
     module Auth
+      extend ::Gitlab::Utils::Override
+
+      override :omniauth_customized_providers
+      def omniauth_customized_providers
+        @omniauth_customized_providers ||=
+          super.concat(%w[kerberos_spnego group_saml])
+      end
+
+      override :omniauth_setup_a_provider
+      def omniauth_setup_a_provider(provider)
+        super
+
+        if provider == 'group_saml'
+          OmniAuth.config.on_failure =
+            ::Gitlab::Auth::GroupSaml::FailureHandler.new(
+              OmniAuth.config.on_failure)
+        end
+      end
+
       def find_with_user_password(login, password)
         if Devise.omniauth_providers.include?(:kerberos)
           kerberos_user = ::Gitlab::Kerberos::Authentication.login(login, password)

lib/gitlab/auth.rb

@@ -16,6 +16,25 @@ module Gitlab
     class << self
       prepend EE::Gitlab::Auth
 
+      def omniauth_customized_providers
+        @omniauth_customized_providers ||= %w[bitbucket jwt]
+      end
+
+      def omniauth_setup_providers(provider_names)
+        provider_names.each do |provider|
+          omniauth_setup_a_provider(provider)
+        end
+      end
+
+      def omniauth_setup_a_provider(provider)
+        case provider
+        when 'kerberos'
+          require 'omniauth-kerberos'
+        when *omniauth_customized_providers
+          require_dependency "omni_auth/strategies/#{provider}"
+        end
+      end
+
       def find_for_git_client(login, password, project:, ip:)
         raise "Must provide an IP for rate limiting" if ip.nil?