This question was previously answered. However the answer is outdated, with ConVirt seemingly dead and no simple instructions for other panels.
My setup is Ubuntu 18.04 with PHP 7 running on Apache Web Server.
A lot of packages I see require other operating system's package managers, or come as a complete OS package like Proxmox.
Is there any simple web UI that can be installed on top of Apache, or can be proxied to by Apache whilst it runs on it's own server?
I've tried Kimichi, but it does not run properly on 18.04