Installing a rack application in Rails does not work

I am trying to install a rack in Rails and it does not work. I recreated the simplest version of my problem. I am using Ruby 1.9.3p327 and Rails 3.2.11.

I started by creating a new rails application using rails new problem_example . By going to the problem_example directory, I can visit the rails application at http://localhost:3000 , and life is beautiful.

Following the instructions in Rack in Rails 3 Railscast , I added the following routes:

 ProblemExample::Application.routes.draw do root :to => proc { |env| [200, {}, ["Oh yeah!"]] } end 

I also deleted the index.html file from the public folder. If I go to http://localhost:3000 , I will see "Oh yes!" output on display.

Here is the hard part. If I change my routes to look like this:

 class SimpleRackApplication def call(env) [200, {'Content-Type' => 'text/plain'}, ["Oh no!"]] end end ProblemExample::Application.routes.draw do root :to => SimpleRackApplication end 

and I run rails s , I get this blank error:

 => Booting WEBrick => Rails 3.2.11 application starting in development on http://0.0.0.0:3000 => Call with -d to detach => Ctrl-C to shutdown server Exiting /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/actionpack-3.2.11/lib/action_dispatch/routing/mapper.rb:181:in `default_controller_and_action': missing :controller (ArgumentError) from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/actionpack-3.2.11/lib/action_dispatch/routing/mapper.rb:78:in `normalize_options!' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/actionpack-3.2.11/lib/action_dispatch/routing/mapper.rb:61:in `initialize' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/actionpack-3.2.11/lib/action_dispatch/routing/mapper.rb:1304:in `new' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/actionpack-3.2.11/lib/action_dispatch/routing/mapper.rb:1304:in `add_route' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/actionpack-3.2.11/lib/action_dispatch/routing/mapper.rb:1284:in `decomposed_match' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/actionpack-3.2.11/lib/action_dispatch/routing/mapper.rb:1270:in `block in match' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/actionpack-3.2.11/lib/action_dispatch/routing/mapper.rb:1270:in `each' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/actionpack-3.2.11/lib/action_dispatch/routing/mapper.rb:1270:in `match' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/actionpack-3.2.11/lib/action_dispatch/routing/mapper.rb:260:in `root' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/actionpack-3.2.11/lib/action_dispatch/routing/mapper.rb:1317:in `root' from /Users/landonschropp/Dropbox/Development/current/problem_example/config/routes.rb:9:in `block in <top (required)>' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/actionpack-3.2.11/lib/action_dispatch/routing/route_set.rb:282:in `instance_exec' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/actionpack-3.2.11/lib/action_dispatch/routing/route_set.rb:282:in `eval_block' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/actionpack-3.2.11/lib/action_dispatch/routing/route_set.rb:260:in `draw' from /Users/landonschropp/Dropbox/Development/current/problem_example/config/routes.rb:8:in `<top (required)>' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:245:in `load' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:245:in `block in load' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:236:in `load_dependency' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:245:in `load' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/application/routes_reloader.rb:40:in `block in load_paths' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/application/routes_reloader.rb:40:in `each' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/application/routes_reloader.rb:40:in `load_paths' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/application/routes_reloader.rb:16:in `reload!' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/application/routes_reloader.rb:26:in `block in updater' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activesupport-3.2.11/lib/active_support/file_update_checker.rb:78:in `call' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activesupport-3.2.11/lib/active_support/file_update_checker.rb:78:in `execute' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/application/routes_reloader.rb:27:in `updater' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/application/routes_reloader.rb:7:in `execute_if_updated' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/application/finisher.rb:66:in `block in <module:Finisher>' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/initializable.rb:30:in `instance_exec' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/initializable.rb:30:in `run' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/initializable.rb:55:in `block in run_initializers' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/initializable.rb:54:in `each' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/initializable.rb:54:in `run_initializers' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/application.rb:136:in `initialize!' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/railtie/configurable.rb:30:in `method_missing' from /Users/landonschropp/Dropbox/Development/current/problem_example/config/environment.rb:5:in `<top (required)>' from /Users/landonschropp/Dropbox/Development/current/problem_example/config.ru:3:in `require' from /Users/landonschropp/Dropbox/Development/current/problem_example/config.ru:3:in `block in <main>' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/rack-1.4.4/lib/rack/builder.rb:51:in `instance_eval' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/rack-1.4.4/lib/rack/builder.rb:51:in `initialize' from /Users/landonschropp/Dropbox/Development/current/problem_example/config.ru:in `new' from /Users/landonschropp/Dropbox/Development/current/problem_example/config.ru:in `<main>' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/rack-1.4.4/lib/rack/builder.rb:40:in `eval' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/rack-1.4.4/lib/rack/builder.rb:40:in `parse_file' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/rack-1.4.4/lib/rack/server.rb:200:in `app' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/commands/server.rb:46:in `app' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/rack-1.4.4/lib/rack/server.rb:304:in `wrapped_app' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/rack-1.4.4/lib/rack/server.rb:254:in `start' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/commands/server.rb:70:in `start' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/commands.rb:55:in `block in <top (required)>' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/commands.rb:50:in `tap' from /Users/landonschropp/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/commands.rb:50:in `<top (required)>' from script/rails:6:in `require' from script/rails:6:in `<main>' 

What's happening?

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1 answer

Oh spirit. You need to create an instance of the Rack application:

 root :to => SimpleRackApplication.new 
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