location /  {
            proxy_pass http://tomcat_server; 
            proxy_set_header Host $http_host; 
            proxy_set_header X-Forward-For $remote_addr; 
            proxy_connect_timeout       10;
            proxy_read_timeout          10;
            proxy_send_timeout          10;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "upgrade";
        }