The problem is that some customers would like an instance of cpanel to send/receive some mail... or they want to host a website and they are familiar with cpanel and just want it set up as soon as possible... or they want to deploy a wordpress site really quick without having to configure anything.

I know that these vultr offers something like this: https://www.vultr.com/apps/ and so does digitalocean https://www.digitalocean.com/products/one-click-apps/

I have a rack of servers I would like to dedicate this, with a /22... Does anything exist out there that someone else has written for me that I can buy/subscribe to?

I was looking at https://hostbillapp.com/products-services/openstack/ but it seems to be vm specific, I guess I could add startup scripts to install certain pre-configured packages, but I really would like that to already have been done by someone else. I also wonder if a docker based backend would be better to not have to deal with the OS overhead that a vm brings.