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apache-kafkaspring-kafka

Spring Kafka Consumer/Listener Group

what is the difference in specifying group at the consumer

spring.kafka.consumer.group-id

vs specifying at the @KafkaListener?

@KafkaListener(topic="test", group = "test-grp")
Solution

  • See the javadocs for the group property; it has nothing to do with the kafka group.id...

    /**
 * If provided, the listener container for this listener will be added to a bean
 * with this value as its name, of type {@code Collection<MessageListenerContainer>}.
 * This allows, for example, iteration over the collection to start/stop a subset
 * of containers.
 * @return the bean name for the group.
 */

    This has been renamed containerGroup in 1.3/2.0.

    Those release versions also provide...

    /**
 * Override the {@code group.id} property for the consumer factory with this value
 * for this listener only.
 * @return the group id.
 * @since 1.3
 */
String groupId() default "";

/**
 * When {@link #groupId() groupId} is not provided, use the {@link #id() id} (if
 * provided) as the {@code group.id} property for the consumer. Set to false, to use
 * the {@code group.id} from the consumer factory.
 * @return false to disable.
 * @since 1.3
 */
boolean idIsGroup() default true;

    Previously, you needed a container factory/consumer factory for each listener; these allow you to use one factory instance and override the group.id.