passenger-rails is a simple gem, clone of unicorn-rails that sets the default server for rack (and rails) to passenger.
passenger-rails overrides the Rack::Handler.default method to return Rack::Handler::Passenger which will cause rack (and
rails) to use passenger by default.
Add this line to your application's Gemfile:
gem 'passenger-rails'
And then execute:
$ bundle install
Just add the gem to your Gemfile and then rails server will default to using passenger.
Fork, branch & pull request.