An overlay network on top of wireguard would be really nice. For example you are running a wireguard network on 169.254.0.0/16. So every peer which is assigned an ip address within this range is by configuration of the network allowed to forward packets to another peer in the 169.254.0.0/16 network. So the only things needed to be implemented would be: * an internal routing system to forward packets on some way to the destination * a concept on how peers are found and how they build a secure channel (pre-shared key?)
Edit: A better way would be to have multiple shared secrets for every server. So you could basically assign roles to every server. So if a server has the keys "db" and "middleware" he can communicate with every same in the network for forwarding but the final destination can only be a server which has also one of the keys "db" od "middleware". Maybe such a server would have 2 virtual ips within the subnet, one for it's role for db and for middleware.