Enter Migration Mode on the Brokers

Enter Migration Mode on the Brokers

Once the KRaft controller quorum has been started, the brokers will need to be reconfigured and restarted. Brokers may be restarted in a rolling fashion to avoid impacting cluster availability. Each broker requires the following configuration to communicate with the KRaft controllers and to enable the migration.

• broker.id: Ensure broker.id is set to a non-negative integer even if broker.id.generation.enable is enabled (default is enabled). Additionally, ensure broker.id does not exceed reserved.broker.max.id to avoid failure.
• controller.quorum.bootstrap.servers
• controller.listener.names
• The controller.listener.name should also be added to listener.security.property.map
• zookeeper.metadata.migration.enable

Here is a sample config for a broker that is ready for migration:

# Sample ZK broker server.properties listening on 9092
broker.id=0
listeners=PLAINTEXT://:9092
advertised.listeners=PLAINTEXT://localhost:9092
listener.security.protocol.map=PLAINTEXT:PLAINTEXT,CONTROLLER:PLAINTEXT

# Set the IBP
inter.broker.protocol.version=3.9

# Enable the migration
zookeeper.metadata.migration.enable=true

# ZooKeeper client configuration
zookeeper.connect=localhost:2181

# KRaft controller quorum configuration
controller.quorum.bootstrap.servers=localhost:9093
controller.listener.names=CONTROLLER

Note: Once the final ZK broker has been restarted with the necessary configuration, the migration will automatically begin. When the migration is complete, an INFO level log can be observed on the active controller:

Completed migration of metadata from Zookeeper to KRaft