> It has to exist on a private network behind a firewall with ports open to application servers and other es nodes only. Running things on a public ip address is a choice that should not be taken lightly. Clustering over the public internet is not a thing with Elasticsearch (or similar products).

I've met at least one cloud provider in the past (small Dutch thing) that provides _only_ public IP addresses. They do have customers, though one less now. Clustering over the public Internet is a thing. It shouldn't, but I could say the same thing about this website and yet here we are.