I’ve used peerage (https://github.com/mrluc/peerage) on kubernetes for SD. It’s simple to set up and works in dev/test using its local adapters.

Libcluster looks good too. Everything bitwalker touches seems to be solid AF.

We're not doing anything special to help set up distributed Erlang at the moment. It would probably be difficult with App Engine because it's designed to manage stateless containers. But I could imagine setting up such a network with Kubernetes Engine, or definitely with Compute Engine VMs.

I can't speak to GCP much, but gigalixir.com is a platform-as-a-service that takes advantage of Erlang's distributed network/nodes. I'm the founder.

It currently doesn't do automated clustering of nodes out of the box. It should be possible to build a clustering strategy for libcluster (https://github.com/bitwalker/libcluster) for App Engine. Note that there's already a kubernetes strategy which could run on the Google Kubernetes Engine.