[NIFI-9839] NiFi fails to startup/join cluster if dataflow consists solely of Controller Services and Reporting Tasks

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.16.0
• Fix Version/s: 1.16.1
• Component/s: Core Framework
• Assignee: Mark Payne
• Reporter: Mark Payne
• Created: 28/Mar/22 15:20
• Updated: 04/Apr/22 18:29
• Resolved: 28/Mar/22 20:58

Description

To replicate:

1. Start a cluster
2. Add one or more controller services to the Root Process Group. Do not add any processors, labels, funnels, ports, etc.
3. Restart cluster

This will result in a stack trace along the lines of:

2022-03-28 11:24:28,230 ERROR org.apache.nifi.web.server.JettyServer: Unable to load flow due to: java.io.IOException: org.apache.nifi.controller.serialization.FlowSynchronizationException: Failed to connect node to cluster because local flow controller partially updated. Administrator should disconnect node and review flow for corruption.
java.io.IOException: org.apache.nifi.controller.serialization.FlowSynchronizationException: Failed to connect node to cluster because local flow controller partially updated. Administrator should disconnect node and review flow for corruption.
	at org.apache.nifi.controller.StandardFlowService.load(StandardFlowService.java:524)
	at org.apache.nifi.web.server.JettyServer.start(JettyServer.java:1086)
	at org.apache.nifi.NiFi.<init>(NiFi.java:170)
	at org.apache.nifi.NiFi.<init>(NiFi.java:82)
	at org.apache.nifi.NiFi.main(NiFi.java:330)
Caused by: org.apache.nifi.controller.serialization.FlowSynchronizationException: Failed to connect node to cluster because local flow controller partially updated. Administrator should disconnect node and review flow for corruption.
	at org.apache.nifi.controller.StandardFlowService.loadFromConnectionResponse(StandardFlowService.java:1057)
	at org.apache.nifi.controller.StandardFlowService.load(StandardFlowService.java:520)
	... 4 common frames omitted
Caused by: org.apache.nifi.controller.serialization.FlowSynchronizationException: java.lang.IllegalStateException: The specified observer identifier (bulletin-observer) already exists.
	at org.apache.nifi.controller.serialization.VersionedFlowSynchronizer.synchronizeFlow(VersionedFlowSynchronizer.java:362)
	at org.apache.nifi.controller.serialization.VersionedFlowSynchronizer.sync(VersionedFlowSynchronizer.java:185)
	at org.apache.nifi.controller.serialization.StandardFlowSynchronizer.sync(StandardFlowSynchronizer.java:43)
	at org.apache.nifi.controller.FlowController.synchronize(FlowController.java:1479)
	at org.apache.nifi.persistence.StandardFlowConfigurationDAO.load(StandardFlowConfigurationDAO.java:104)
	at org.apache.nifi.controller.StandardFlowService.loadFromBytes(StandardFlowService.java:815)
	at org.apache.nifi.controller.StandardFlowService.loadFromConnectionResponse(StandardFlowService.java:1026)
	... 5 common frames omitted
Caused by: java.lang.IllegalStateException: The specified observer identifier (bulletin-observer) already exists.
	at org.apache.nifi.logging.repository.StandardLogRepository.addObserver(StandardLogRepository.java:169)
	at org.apache.nifi.controller.flow.StandardFlowManager.createControllerService(StandardFlowManager.java:490)
	at org.apache.nifi.groups.StandardProcessGroupSynchronizer.addControllerService(StandardProcessGroupSynchronizer.java:1033)
	at org.apache.nifi.groups.StandardProcessGroupSynchronizer.synchronizeControllerServices(StandardProcessGroupSynchronizer.java:457)
	at org.apache.nifi.groups.StandardProcessGroupSynchronizer.synchronize(StandardProcessGroupSynchronizer.java:339)
	at org.apache.nifi.groups.StandardProcessGroupSynchronizer.lambda$synchronize$0(StandardProcessGroupSynchronizer.java:221)
	at org.apache.nifi.controller.flow.AbstractFlowManager.withParameterContextResolution(AbstractFlowManager.java:462)
	at org.apache.nifi.groups.StandardProcessGroupSynchronizer.synchronize(StandardProcessGroupSynchronizer.java:219)
	at org.apache.nifi.groups.StandardProcessGroup.synchronizeFlow(StandardProcessGroup.java:3830)
	at org.apache.nifi.controller.serialization.VersionedFlowSynchronizer.synchronizeFlow(VersionedFlowSynchronizer.java:353)
	... 11 common frames omitted 

However, if any other components are added to the root group, such as a process or a child process group, this won't happen.

Issue Links

• links to: GitHub Pull Request #5910