For example, solutions like Proxmox are really nice and sophisticated, but only if you're dealing with instances of Proxmox, of course. Of course, you can connect and manage them from a single instance. And it's no wonder that dedicated server companies provide Proxmox's ready-to-use ISOs as well as ESXi as an ideal solution for distributing a dedicated server across multiple virtual machines.
But what happens if you manage virtual machines, containers or dedicated servers spread across different public clouds or hosting providers? For example. KVM-based virtual machines on DigitalOcean / Linode, LXC containers on Proxmox hosts, pure solutions at OVH / Hetzner, etc.? Ideally, without an agent, although the installation of an agent would make my life easier overall.
The goal is to have something easy to install and maintain. Use a single server as a "master" node, and then connect and manage any other slave server (virtual, container, or dedicated) using SSH commands or an agent. A simple web-based GUI could be used to report health status and resource usage and (why not) perhaps run remote shell commands.
There is obviously no need for calculation / storage / network separation.
Until here I watched:
a) orchestration tools such as Ansible, Chef, Puppet, etc. or Kubernetes / Swarm (although intended primarily, if not exclusively, for containers), but they are either limited to the CLI or really excessive to install.
b) OpenStack = shoot me now (sorry OpenStack users)
c) OpenNebula is probably close to such a need, but it also seems a little excessive to set up (but not too complex if you tried Kubernetes).
d) oVirt is very nice, but it requires CentOS as the base operating system (for slave nodes) – it's a problem if a remote virtual machine is already configured with Ubuntu.
Thank you in advance for any suggestions / pointers.