2 files changed, 22 insertions, 0 deletions
diff --git a/railties/lib/rails/rack.rb b/railties/lib/rails/rack.rb
index 90535674e9..f721abddc8 100644
--- a/railties/lib/rails/rack.rb
+++ b/railties/lib/rails/rack.rb
@@ -2,6 +2,7 @@ module Rails
   module Rack
     autoload :Debugger, "rails/rack/debugger"
     autoload :Logger, "rails/rack/logger"
+    autoload :Metal, "rails/rack/metal"
     autoload :Static, "rails/rack/static"
   end
 end
diff --git a/railties/lib/rails/rack/metal.rb b/railties/lib/rails/rack/metal.rb
new file mode 100644
index 0000000000..8dfbedad90
--- /dev/null
+++ b/railties/lib/rails/rack/metal.rb
@@ -0,0 +1,21 @@
+module Rails
+  module Rack
+    class Metal
+      NotFound = lambda { |env|
+        [404, {"Content-Type" => "text/html"}, "Not Found"]
+      }
+
+      def self.call(env)
+        new(NotFound).call(env)
+      end
+
+      def initialize(app)
+        @app = app
+      end
+
+      def call(env)
+        @app.call(env)
+      end
+    end
+  end
+end