Page History

...

This KIP introduces one new broker-side extension interface and one new broker configuration.

New Interface

org.apache.kafka.coordinator.group.api.ConsumerGroupRebalanceListener:

 // callback when a consumer group rebalance is detected by the Group Coordinator.

...

/**
 * A callback interface that users can implement to get notified when a consumer group rebalance occurs.
 * <p>
 * This listener is invoked on the broker side (GroupCoordinator) when a consumer group's epoch is bumped,
 * which indicates that a rebalance has occurred.

 * Implementations of this interface can be used for monitoring, alerting, or logging purposes
 * to track which consumer groups are experiencing rebalances.
 */
public interface ConsumerGroupRebalanceListener {

    /**
     * Called when a consumer group rebalance occurs.
     *
     * @param groupId The ID of the consumer group that rebalanced
     * @param groupEpoch The new group epoch after the rebalance
     * @param metadataHash The metadata hash of the group after the rebalance
     */
    void onConsumerGroupRebalance(String groupId, int groupEpoch, long metadataHash);
}

New Broker Configuration

group.consumer.rebalance.listener.classes (LIST, default: empty)

...