Create another test that starts both a block producer and a relay node

[aciceri]

Starting from this test create another one that starts also a relay node.

For now I would say to do this on the same NixOS host. My idea is adding a boolean option to the existing block producer module that when enabled (probably by default it should be true) instead of just creating a systemd service for the block producer it also creates a relay node. Then it makes the relay node able to access the block producer node but blocks it from the external connections.

[zmrocze]

little trouble is that both nodes boil down to services.cardano-node so need to sth a bit cleverer to run both nodes on one machine

[zmrocze]

just quickly what i can now think of is:

I wouldn't care to run both nodes on single host, because 1) that's not a real usecase as the whole point of having two nodes was to split block producer from network access completely 2) to just implement it for tests is a waste of time because by the design of cardano-node module you'd probably have to use nixos-containers at which point you're doing something similar to running two machines in tests, so lets just run 2 machines.

[zmrocze]

@aciceri what do you think