Command Center error: No Schema Registry clusters found

Schema Registry
1

I’m running Confluent local, multi-broker setup.
I’ve followed the instructions to turn do with schema reg at Broker-side Schema ID Validation | Confluent Documentation, including setting

confluent.schema.registry.url=http://schema-registry:8081

Now i see a warning message at the top of the command centre GUI:

No Schema Registry clusters found to match definition in broker properties (‘confluent.schema.registry.url’) - please check configuration in control-center properties.

How do i address this?

2

Can you please show the output of the HTTP response, from the Control Center server?

REGISTRY=$(grep confluent.schema.registry.url /path/to/control-center.properties | cut -d= -f2)
curl "http://$REGISTRY/subjects"
3

Thanks @OneCricketeer
I haven’t specified confluent.schema.registry.url in the control-center.properties file. Do i need to?

There is a commented property already in the file, which i’ve uncommented

confluent.controlcenter.schema.registry.url=http://localhost:8081

The link below specifies the setting you mentioned is needed in server.properties file (so i’ve added it there), saying,

This setting is required to make Schema Validation available both from the Confluent CLI and on the Confluent Control Center.

https://docs.confluent.io/platform/current/schema-registry/schema-validation.html?_ga=2.158399866.1795121181.1684159685-1574708521.1668441156#prerequisites-and-setting-sr-urls-on-the-brokers

4

Actually @OneCricketeer, your reply jogged my memory - i did try adding confluent.schema.registry.url previously to control-center.properties. I’ve just done it again and restarted the control center - shows the error i saw previously (and hence assumed the prop confluent.schema.registry.url had to be wrong and the correct prop the commented one already present i.e. “confluent.controlcenter.schema.registry.url”).

[2023-05-16 18:10:49,542] ERROR [_confluent-controlcenter-7-2-0-1-662d0577-3265-4c85-8cf0-549a3d692a3c-StreamThread-3] streams exception (io.confluent.controlcenter.streams.KafkaStreamsManager)
org.apache.kafka.streams.errors.StreamsException: failed to initialize processor KSTREAM-AGGREGATE-0000000018
	at org.apache.kafka.streams.processor.internals.ProcessorNode.init(ProcessorNode.java:108)
	at org.apache.kafka.streams.processor.internals.StreamTask.initializeTopology(StreamTask.java:950)
	at org.apache.kafka.streams.processor.internals.StreamTask.completeRestoration(StreamTask.java:260)
	at org.apache.kafka.streams.processor.internals.TaskManager.tryToCompleteRestoration(TaskManager.java:479)
	at org.apache.kafka.streams.processor.internals.StreamThread.initializeAndRestorePhase(StreamThread.java:865)
	at org.apache.kafka.streams.processor.internals.StreamThread.runOnce(StreamThread.java:747)
	at org.apache.kafka.streams.processor.internals.StreamThread.runLoop(StreamThread.java:589)
	at org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:551)
Caused by: java.lang.NullPointerException
	at org.apache.kafka.streams.kstream.internals.TimestampedTupleForwarder.<init>(TimestampedTupleForwarder.java:45)
	at org.apache.kafka.streams.kstream.internals.KStreamWindowAggregate$KStreamWindowAggregateProcessor.init(KStreamWindowAggregate.java:98)
	at org.apache.kafka.streams.processor.internals.ProcessorNode.init(ProcessorNode.java:105)
	... 7 more
5

I’ve seen that error reported as a bug in KStreams, I believe… Are you able to use a newer version of Confluent Platform than 7.2 for running Control Center?