NodeJS + Socket.IO app served through Nginx proxy

node_nginx_proxy.conf

# Node JS app backend
upstream node_server {
    server 127.0.0.1:3003;
}
server {
        server_name app.example.com;

        #forward to NodeJS app
        location / {
                proxy_pass http://node_server;
                proxy_set_header Host $host;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                #websocket support
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection "upgrade";
                proxy_http_version 1.1;
        }
        #server static contents
        location ~* ^(?!/socket.io/).*\.(jpg|jpeg|gif|png|ico|css|zip|tgz|gz|rar|bz2|pdf|txt|tar|wav|bmp|rtf|js|flv|swf|html|htm|svg|woff)$ {
                root   /home/www/node-app/public;
                expires 30d;
                access_log off;
        }

        location ~ /\.(ht|git) {
                deny all;
        }

}