Implement service discovery where ZooKeeper is the service registry.
Discover the appropriate URLs to declare in the Knox topology for the services specified in the simple topology descriptor.
Need to determine to what degree Hadoop services are registering their details in ZooKeeper, and may need to encourage them to do so or augment what they're already registering.
This must be named something less generic than "ZooKeeper" Service Discovery, since the implementation will depend on the structure of the data registered by the services, and will not be a general-purpose ZooKeeper service discovery mechanism.
Here is a link to the existing YARN Service Registry docs - we will need to determine whether there is enough fidelity in the metadata available there to actual generate topologies from it. https://hadoop.apache.org/docs/stable/hadoop-yarn/hadoop-yarn-site/registry/yarn-registry.html