app.rb

#!/usr/bin/env ruby

require 'sinatra'

class Pumatra < Sinatra::Base
  get '/' do
    return 'It works!'
  end
end

if __FILE__ == $0
  Pumatra.run!
end

config.ru

#!/usr/bin/env ruby

require './app'
Pumatra.run!

Gemfile

source "https://rubygems.org"

gem 'puma'
gem 'sinatra'

puma.rb

root = "#{Dir.getwd}"

activate_control_app "tcp://127.0.0.1:9293"
bind "unix:///tmp/puma.pumatra.sock"
pidfile "#{root}/tmp/pids/puma.pid"
rackup "#{root}/config.ru"
state_path "#{root}/tmp/pids/puma.state"