Comment by winsletts

The problem with etcd members on every Postgres node is that clusters fixed nodes or members. etcd doesn't function well in an environment where you could tear down / build up new nodes. Most of our Postgres service runs on AWS, and thus we must expect that any single node may vanish, and our system must replace that node. We tried running etcd alongside Postgres in an early prototype, but ran into issues with etcd cluster stability when destroying and recreating nodes. Thus, we opt for a stand alone etcd cluster distinct from the Postgres cluster.