I am currently running Apache NiFi as a StatefulSet on Kubernetes. I'm testing to see how the cluster recovers if I kill a pod but am experiencing a problem when the pod (NiFi node) rejoins the cluster.

The node will rejoin as an additional node instead of appearing as it's original identity. For example, if I have a 3 node NiFi cluster and kill and restart one pod/NiFi node I will end up with a 4 node cluster with one disconnected.

Before:

After:

I believe that the NiFi node is identified somehow in a config file which isn't persisting when it is killed. So far I am using persistent volumes to persist the following config files:

• state-management.xml
• authorizers.xml

I haven't persisted nifi.properties (it is dynamically generated on startup a and I can't see anything in there that could uniquely identify the node).

So I guess, the question is how is the node uniquely identified to the server and where is it stored?

EDIT: I'm using an external Zookeeper.

Thank you in advance,

Harry