What provisioning do you use to integrate with your cloud providers api?
I'm curious how etcd is bootstrapping? I don't see a better way to do it than using multicasting.
BTW: I absolutely hate that consul (and looks like etcd has this issue as well) is using http for communicating. It's so inefficient to obtain updates about changes these way. Zookeeper which everyone loves to hate (and it wasn't even created for service discovery), did this so much better, you have a single long standing connection where you subscribe what updates you want to receive, it has much lower overhead and is simpler to code with.
Another thing that seems to be lost buy people who promote their service discovery solution is that you don't need to be always consistent and eventually consistent is perfectly fine. You don't really need raft or paxos to do it.
Again, I did not work with etcd yet, but in consul because it's "RESTful" i when you monitor multiple services you need to maintain multiple requests.
Edit: Reading more about http 2's frames and pipelining, looks like it's possible to use it similar way it's done in ZK[1]. If GRPC allows that then I suppose it indeed solves this problem.
[1] having a single long standing connection that's not closed after receiving a response. The request frames could be used to place watches and response frames would send the updates to the client.