All of the tools are based on similar principles and architecture. They run on nodes, require a quorum to operate and are strongly consistent. They all provide some form of key/value storage.
Zookeeper is the oldest of the three, and the age shows in its complexity, utilization of resources and goals it's trying to accomplish. It was designed in a different age than the rest of the tools we evaluated (even though it's not much older).
etcd with Registrator and
confd is a very simple, yet very powerful combination that can solve most, if not all, of our service discovery needs. It showcases the power we can obtain when we combine simple and very specific tools. Each of them performs a very specific task, communicates ...