The basics of NiFi clustering
Clustering in Apache NiFi follows a Zero-Master Clustering architecture. In this type of clustering, there is no pre-defined master. Every node can perform the same tasks, and the data is split between them. NiFi uses Zookeeper when deployed as a cluster.
Zookeeper will elect a Cluster Coordinator. The Cluster Coordinator is responsible for deciding whether new nodes can join – the nodes will connect to the coordinator – and to provide the updated flows to the new nodes.
While it sounds like the Cluster Coordinator is the master, it is not. You can make changes to the data pipelines on any node and they will be replicated to all the other nodes, meaning a non-Cluster Coordinator or a non-Primary Node can submit changes.
The Primary Node is also elected by Zookeeper. On the Primary Node, you can run isolated processes. An isolated process is a NiFi processor that runs only on the Primary Node. This is important because think what...