Heroku supports Rack and Rack-based web frameworks like Sinatra, Ramaze, and Camping. To run a Rack-based app, include a Gemfile, as well as a rackup file named config.ru in the app’s root directory. The config.ru file convention has become common, so most existing Rack applications should not require changes to deploy to Heroku. Pure Rack apps First, create a new directory and write a simple conf