Just wanted to share our setup, as reminder and help for others 😉

(do not forget to create a tmp and public folder inside your projects folder)

#/opt/nginx/conf/nginx.conf
server {
  listen 80;
  server_name xxx.yyy.com;

  access_log /var/log/xxx_access.log  main;
  error_log /var/log/xxx_error.log debug;
  root /srv/xxx/public;   # <--- be sure to point to 'public'!
  passenger_use_global_queue on;
}

#/etc/hosts
127.0.0.1       xxx.yyy.com

#config.ru
require 'app'
disable :run
set :root, Pathname(__FILE__).dirname
run Sinatra::Application

#app.rb
require 'rubygems'
require 'sinatra'

get "/" do
  "Hello world from xxx"
end