Nginx Nodejs Express Config

server {
        listen 80;
        listen [::]:80;

        root /var/www/example.com/site;
        index index.html index.htm index.nginx-debian.html;

        server_name example.com www.example.com;

        location / {
                proxy_pass http://localhost:3000;
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection 'upgrade';
                proxy_set_header Host $host;
                proxy_cache_bypass $http_upgrade;
        }

        location ~ ^/(images/|img/|javascripts/|js/|css/|stylesheets/|flash/|media/|static/|robots.txt|humans.txt|favicon.ico) {
          root /var/www/example.com/site/public;
          access_log off;
          expires max;
        }
}