Redundant PHP-fpm service
Now the service stack has a load balancer, redundant Nginx web servers, but the PHP-fpm server is still only a single service. Most of the processing happens in the PHP-fpm server when serving a page request. The part prohibiting us from replicating the PHP-fpm service is that session data is stored in the local filesystem on the server. So if we just replicated the PHP-fpm server without replicating the sessions it would not work.
In this part, we will do the necessary changes to support a redundant PHP-fpm service.