Hello,
I would like to report a mistake in the Kafka 3.7 Documentation -> 6.10 KRaft
-> ZooKeeper to KRaft Migration -> Reverting to ZooKeeper mode During the
Migration.
While migrating my Kafka + Zookeeper cluster to KRaft and testing rollbacks at
a different migration stages I have noticed, that "Directions for reverting"
provided for "Migrating brokers to KRaft" are wrong.
Following the first step provided in documentation you suppose to : On each
broker, remove the process.roles configuration, and restore the
zookeeper.connect configuration to its previous value. If your cluster requires
other ZooKeeper configurations for brokers, such as zookeeper.ssl.protocol,
re-add those configurations as well. Then perform a rolling.
In that case, if you remove process.roles configuration and restore
zookeeper.connect as well as other ZooKeeper configuration (If your cluster
requires) you will receive an error that looks like this:
[2024-05-28 08:09:49,396] lvl=ERROR Exiting Kafka due to fatal exception
logger=kafka.Kafka$
java.lang.IllegalArgumentException: requirement failed:
controller.listener.names must be empty when not running in KRaft mode:
[CONTROLLER]
at scala.Predef$.require(Predef.scala:337)
at kafka.server.KafkaConfig.validateValues(KafkaConfig.scala:2441)
at kafka.server.KafkaConfig.<init>(KafkaConfig.scala:2290)
at kafka.server.KafkaConfig.<init>(KafkaConfig.scala:1639)
at kafka.Kafka$.buildServer(Kafka.scala:71)
at kafka.Kafka$.main(Kafka.scala:90)
at kafka.Kafka.main(Kafka.scala)
However I was able to perform rollback successfully by performing additional
steps:
* Restore zookeeper.metadata.migration.enable=true line in broker
configuration;
* We are using authorizer.class.name, so it also had to be reverted:
org.apache.kafka.metadata.authorizer.StandardAuthorizer ->
kafka.security.authorizer.AclAuthorizer;
I believe that should be mentioned.
Edgar Zubel
DevOps Engineer
edgar.zu...@teliacompany.com<mailto:edgar.zu...@teliacompany.com>
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