Make generated Metal bits a pure rack endpoint application (not middleware)

Instead of calling super to pass the request on, return a 404.
The modified app looks like this:

  # app/metal/poller.rb
  class Poller
    def self.call(env)
      if env["PATH_INFO"] =~ /^\/poller/
        [200, {"Content-Type" => "text/html"}, "Hello, World!"]
      else
        [404, {"Content-Type" => "text/html"}, "Not Found"]
      end
    end
  end

But you aren't locked in to just Rails:

  # app/metal/api.rb
  require 'sinatra'
  Sinatra::Application.default_options.merge!(:run => false, :env => :production)
  Api = Sinatra.application unless defined? Api

  get '/interesting/new/ideas' do
    'Hello Sinatra!'
  end

1 files changed, 1 insertions, 3 deletions

diff --git a/railties/lib/initializer.rb b/railties/lib/initializer.rb
index f22e34c7dc..637fe74313 100644
--- a/railties/lib/initializer.rb
+++ b/railties/lib/initializer.rb
@@ -536,9 +536,7 @@ Run `rake gems:install` to install the missing gems.
     end
 
     def initialize_metal
-      Dir["#{configuration.root_path}/app/metal/*.rb"].each do |file|
-        configuration.middleware.use(File.basename(file, '.rb').camelize)
-      end
+      configuration.middleware.use Rails::Rack::Metal
     end
 
     # Initializes framework-specific settings for each of the loaded frameworks