How to set port for Rack app?

Question

builder.rb:

def app
  Rack::Builder.new do
    run App.new
  end.to_app
end

How to run on a given port?

Answer 1

Try:

Rack::Handler.default.run(app, :Port => 3000)

Although it would be more typical to run your app in a config.ru file and specify port as a command line option to rackup, e.g.: rackup -p 3000.

Answer 2

When you rackup just specify it with option -p so:

rackup -p 8808 would work just fine.