Server Architecture Needed

We need to host multiple sites on multiple servers in same datacenter. Containers will comunicate to eachother via private ip( please take a closer look at open ports - between containers, we need to close ports on back-end servers).
We need memory and processor share-ing between containers(cgroups v2 -(cant post the link here)
First will need to use CSF(this won't be in docker)+ loadbalancer/s (haproxy) (1 or 2)+ server cache(nginx) + webservers 2 or 3(nginx)+ php-fpm(latest)+ loadbalancer(haproxy for databases)+ redis(for caching databases requests)+ mariadb galera cluser or clusters + monitoring.
We don't know if above setup is correct, we can talk it over. Basically we need nginx with pagespeed module and with certbot (let's encrypt)+ php-fpm latest+ galera cluser. The others we can consult on it.
Basically we need to place as many sites as we want in this setup and if we need more power just rent another server and install docker with needed container. If a harddisk crashes we need site/s to be online until hosting will replace the the faulty hdd. Don't know if this can be done for multiple websites or just for one, so let's talk first

So are you wanting to set up a cluster or just a cloud set up using docker or virtuozzo or something like that.

I guess the better question what is it that you are really trying to do? Are you trying to set up your own hosting company and offer hosting to your customers?

If you are looking to set up several servers with load balancer and so on this set up wont be cheap.