Rails 4.2 Nginx + Passenger

server {
    listen 80;

    server_name kartoffel.example.org;

    keepalive_timeout 5;

    root /var/www/kartoffel/current/public;

    access_log      /var/log/nginx/kartoffel.access.log;
    error_log       /var/log/nginx/kartoffel.error.log warn;

    passenger_enabled on;

    # Rails error pages
    error_page 500 502 503 504 /500.html;
    location = /500.html {
      root /var/www/kartoffel/current/public;
    }

    location ~ ^/assets/  {
      root /var/www/kartoffel/current/public;
      gzip_static on; # to serve pre-gzipped version
      expires max;
      add_header Cache-Control public;
    }
  }

passenger_pre_start http://kartoffel.example.org/;