I am looking forward to eliminate SPOF in my PHP/Nginx/MariaDB/Redis WordPress website. For this purpose, I am about to move from a single server to a more complex HA scenario that as far as I understand (please correct me) will do the trick for me.
My provider is Hetzner Cloud and my plans so far are:
1) Load balancer - Im gonna use CloudFlare's load balancing feature. 100% uptime, no SPOF here.
2) Three app nodes (WordPress Files only) that will rsync (or GlusterFS) between (or gonna use a Volume space, attached to every machine).
3) Three more db nodes onto a Galera cluster that will auto-prevent SPOF. On each node, a local twemproxy and a local Redis service will run. twemproxy will have three nodes to spread Redis' keys at, in its config. It will also preserve the SPOF functionality, since it includes failover functionality ( by adding https://github.com/areina/smitty ). All of those configs (1 in each node) will be identical.
4) A floating IP that will check galera nodes / twemproxies using a hand written script, and based on Hetzner Cloud's API, it will reassign itself to an alive node. My app nodes will have this IP as db_host in wp-config.php
There is a big issue at the moment, that Hetzner Cloud is not offering local networking, but lets skip this at the moment. Its more important for me to verify that this setup is okay against any SPOF (and I might probably move it to another provider).
I am wondering if someone of you has similar setups and if theres something I miss from the above scenario, when it comes to SPOF.