1 files changed, 31 insertions, 0 deletions
diff --git a/railties/lib/rails/app_updater.rb b/railties/lib/rails/app_updater.rb
new file mode 100644
index 0000000000..e53d1cf093
--- /dev/null
+++ b/railties/lib/rails/app_updater.rb
@@ -0,0 +1,31 @@
+require "rails/generators"
+require "rails/generators/rails/app/app_generator"
+
+module Rails
+  class AppUpdater # :nodoc:
+    class << self
+      def invoke_from_app_generator(method)
+        app_generator.send(method)
+      end
+
+      def app_generator
+        @app_generator ||= begin
+          gen = Rails::Generators::AppGenerator.new ["rails"], generator_options, destination_root: Rails.root
+          File.exist?(Rails.root.join("config", "application.rb")) ? gen.send(:app_const) : gen.send(:valid_const?)
+          gen
+        end
+      end
+
+      private
+        def generator_options
+          options = { api: !!Rails.application.config.api_only, update: true }
+          options[:skip_active_record] = !defined?(ActiveRecord::Railtie)
+          options[:skip_action_mailer] = !defined?(ActionMailer::Railtie)
+          options[:skip_action_cable]  = !defined?(ActionCable::Engine)
+          options[:skip_sprockets]     = !defined?(Sprockets::Railtie)
+          options[:skip_puma]          = !defined?(Puma)
+          options
+        end
+    end
+  end
+end