Nginx + puma

host.conf

upstream site {
  server unix:///var/www/example.com/shared/tmp/puma.sock;
}

server {
  listen       80;
  server_name  example.com www.example.com;
  root      /var/www/example.com/current/public;
  access_log  /var/log/nginx/example.com/access.log main;
  error_log /var/log/nginx/example.com/error.log info;

  location / {
    proxy_set_header Host      $host;
    if (!-f $request_filename) {
      proxy_pass http://site;
      break;
    }
  }
}