How to do it...

By default, NGINX enables keep alive connections for non-proxied connections. This means that the connection between NGINX and the browser has already been optimized. However, as keepalive packets require HTTP/1.1 support, it's not enabled by default for reverse proxy connections. Using our Express example from Chapter 3, Common Frameworks, we can add the additional directives:

server { 
    listen       80; 
    server_name  express.nginxcookbook.com; 
 
    access_log  /var/log/nginx/express-access.log  combined; 
 
    location / { 
        proxy_pass http://127.0.0.1:3000; 
        proxy_http_version 1.1; 
        proxy_set_header Upgrade $http_upgrade; 
        proxy_set_header Connection "upgrade"; 
        keepalive 8; 
    } 
}