[NIFI-7559] NiFi Cluster page shows multiple entries for same node identity

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 1.9.1, 1.9.2
• Component/s: Core Framework, Core UI
• Environment: Linux
• Flags: Important
• Assignee: Unassigned
• Reporter: Mohammed Nadeem
• Created: 18/Jun/20 21:31
• Updated: 17/Jul/20 19:45
• Resolved: 17/Jul/20 19:45

Description

In a containerized environment, When a NiFi node doesn't meet health probes performed by Kubelet (Kubernetes), then the node is killed and restarted. This may loop continuously causing NiFi Cluster page ( Hamburger Menu -> Cluster ) to show multiple entries for the same node that gets restarted again and again.

To replicate the issue:
1. Setup single-node cluster ( statefulset application with replicaCount = 1)
2. Change configured probes such as Startup or Liveness to duration less than regular node start up time .
3. Scale new node (replicaCount), for example from 1 to 2. Then new scaled node node-1 gets killed and restarted continuously by kubelet . 

Please check the screenshot below.

nifi-1:8080 is being added 7 times when it should be added just once, This shows  incorrect 1/8 nodes cluster summary when expected behavior is just 1/2 nodes .