I’m having a play with trying to migrate a zookeeper backed 3.4 cluster to KRaft, using confluent platform 7.4. This is just using a local docker cluster. I’ve had the cluster running in zookeeper mode, and also in KRaft (no migration) mode, all seems fine. When trying to migrate the cluster from zookeeper to KRaft though it seems to be waiting for the brokers to join the cluster. The setup is 2 brokers, one controller and one zookeeper node. After everything comes up I see this constantly every second on the controller:
docker-kafka-app_3-1 | [2023-06-29 07:47:15,397] INFO Still waiting for ZK brokers [1, 2] to register with KRaft. (org.apache.kafka.metadata.migration.KRaftMigrationDriver)
docker-kafka-app_3-1 | [2023-06-29 07:47:15,610] INFO [MetadataLoader 3] handleSnapshot: generated a metadata delta from a snapshot at offset 1109 in 6 us. (org.apache.kafka.image.loader.MetadataLoader)```
The output of the following commands seems to indicate all is ok though?
```/usr/bin/kafka-metadata-quorum --bootstrap-server 127.0.0.1:9092 describe --status
ClusterId: tS8_4J0QRf6GTTI0BMxABw
LeaderId: 3
LeaderEpoch: 3
HighWatermark: 509
MaxFollowerLag: 0
MaxFollowerLagTimeMs: 0
CurrentVoters: [3]
CurrentObservers: [1,2]```
```/usr/bin/kafka-metadata-quorum --bootstrap-server 127.0.0.1:9092 describe --replication
NodeId LogEndOffset Lag LastFetchTimestamp LastCaughtUpTimestamp Status
3 601 0 1688024580554 1688024580554 Leader
1 601 0 1688024580142 1688024580142 Observer
2 601 0 1688024580140 1688024580140 Observer ```