Rails relative URL middleware

README.rb

config.action_controller.relative_url_root = '/somebaseurl'

config.middleware.use RecodeUrl

class RecodeUrl
  def initialize(app, options = {})
    @app = app
  end

  def call(env)
    # binding.pry
    env['PATH_INFO'] = env['PATH_INFO'].sub('/somebaseurl','/') 
    @app.call(env)
  end
end

config.ru

map ActionController::Base.config.relative_url_root || "/" do
  run FooApp::Application
end

routes.rb

scope (ActionController::Base.config.relative_url_root || "/") do
  # all your routes
end