How to create heroku based Sinatra apps

I am trying to create Sinatra based heroku app without any luck?

From stackoverflow

• To answer your question: Yes!

  For reference: http://docs.heroku.com/rack#sinatra

• The sinatra application should be as you always do but on the root of your application you should include a config file named config.ru

  It basically says:

  require 'application' run

  Sinatra::Application