app_vhost

# /etc/nginx/sites-enabled/app_vhost
server {
    listen   80;

    root /var/www/com/example/app/docdir;
    server_name *.example.com example.com;
    index index.php;

    location / {
      try_files $uri $uri/ @kohana;
    }

    location ~ /\. {
      deny all;
      access_log off;
      log_not_found off;
    }

    location ~* ^.+\.(jpg|jpeg|gif|png|ico)$ {
      access_log off;
    }

    location ~ \.php$ {
      include fastcgi_params;
      fastcgi_pass unix:/tmp/example-fpm.socket;
    }
    location @kohana {
      include fastcgi_params;
      fastcgi_param SCRIPT_FILENAME $document_root/index.php;
      fastcgi_pass unix:/tmp/example-fpm.socket;
    }
}

default

# /etc/nginx/sites-enabled/default
server {
    listen 80 default;
    server_name _;
 
    root  /var/www/default/htdocs;
  }

nginx.conf.erb

user www-data;
worker_processes  4;

error_log  /var/log/nginx/error.log;
pid        /var/run/nginx.pid;

events {
    worker_connections  1024;
}

http {
    include     /etc/nginx/mime.types;
    access_log  /var/log/nginx/access.log;

    sendfile        on;

    keepalive_timeout  65;
    tcp_nodelay        on;

    gzip  on;
    gzip_disable "MSIE [1-6]\.(?!.*SV1)";

    proxy_set_header Host $host;

    upstream lb {
        ip_hash;
        server app0.example.com:80;
    }

    server {
        listen 80;
        server_name example.com *.example.com;
        location / {
            proxy_pass http://lb;
        }
    }
}