Connecting NiFi to Apache ZooKeeper

NiFi in cluster mode requires an Apache ZooKeeper ensemble for state management and leader election purposes, the Stackable operator for Apache NiFi does not support single node deployments without ZooKeeper, hence this is a required setting.

Configuration happens via a discovery ConfigMap, which needs to contain two keys called ZOOKEEPER_HOSTS with the value being the ZooKeeper connection string and ZOOKEEPER_CHROOT with the value being the ZooKeeper chroot. When using the Stackable operator for Apache ZooKeeper, the operator creates this ConfigMap for every ZNode automatically.