config.ru

# rack mapping example
# run at port 9292 with "rackup config.ru"

require 'path_to_my_rails_app/config/environment'
app1 = Rack::Builder.new {
  map "/" do
    use Rails::Rack::Static
    run ActionController::Dispatcher.new
  end
}.to_app

app2 = Proc.new{ |env| [200, {'Content-Type' => 'text/html'}, "Hi from app 2"] }

map "/foo" do
  run app1
end
 
map "/bar" do
  run app2
end