Auto-configure Kafka listener container with rebalance listener

This commit associates a `ConsumerAwareRebalanceListener` to the
auto-configured listener container factory if a single instance is found
in the context.

See gh-16755

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/kafka/ConcurrentKafkaListenerContainerFactoryConfigurer.java

@@ -25,6 +25,7 @@ import org.springframework.kafka.core.ConsumerFactory;
 import org.springframework.kafka.core.KafkaTemplate;
 import org.springframework.kafka.listener.AfterRollbackProcessor;
 import org.springframework.kafka.listener.BatchErrorHandler;
+import org.springframework.kafka.listener.ConsumerAwareRebalanceListener;
 import org.springframework.kafka.listener.ContainerProperties;
 import org.springframework.kafka.listener.ErrorHandler;
 import org.springframework.kafka.support.converter.MessageConverter;
@@ -53,6 +54,8 @@ public class ConcurrentKafkaListenerContainerFactoryConfigurer {
 
 	private AfterRollbackProcessor<Object, Object> afterRollbackProcessor;
 
+	private ConsumerAwareRebalanceListener rebalanceListener;
+
 	/**
 	 * Set the {@link KafkaProperties} to use.
 	 * @param properties the properties
@@ -111,6 +114,15 @@ public class ConcurrentKafkaListenerContainerFactoryConfigurer {
 		this.afterRollbackProcessor = afterRollbackProcessor;
 	}
 
+	/**
+	 * Set the {@link ConsumerAwareRebalanceListener} to use.
+	 * @param rebalanceListener the rebalance listener.
+	 * @since 2.2
+	 */
+	void setRebalanceListener(ConsumerAwareRebalanceListener rebalanceListener) {
+		this.rebalanceListener = rebalanceListener;
+	}
+
 	/**
 	 * Configure the specified Kafka listener container factory. The factory can be
 	 * further tuned and default settings can be overridden.
@@ -160,6 +172,7 @@ public class ConcurrentKafkaListenerContainerFactoryConfigurer {
 		map.from(properties::getLogContainerConfig).to(container::setLogContainerConfig);
 		map.from(properties::isMissingTopicsFatal).to(container::setMissingTopicsFatal);
 		map.from(this.transactionManager).to(container::setTransactionManager);
+		map.from(this.rebalanceListener).to(container::setConsumerRebalanceListener);
 	}
 
 }

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/kafka/KafkaAnnotationDrivenConfiguration.java

@@ -29,6 +29,7 @@ import org.springframework.kafka.core.ConsumerFactory;
 import org.springframework.kafka.core.KafkaTemplate;
 import org.springframework.kafka.listener.AfterRollbackProcessor;
 import org.springframework.kafka.listener.BatchErrorHandler;
+import org.springframework.kafka.listener.ConsumerAwareRebalanceListener;
 import org.springframework.kafka.listener.ErrorHandler;
 import org.springframework.kafka.support.converter.BatchMessageConverter;
 import org.springframework.kafka.support.converter.BatchMessagingMessageConverter;
@@ -63,6 +64,8 @@ class KafkaAnnotationDrivenConfiguration {
 
 	private final AfterRollbackProcessor<Object, Object> afterRollbackProcessor;
 
+	private final ConsumerAwareRebalanceListener rebalanceListener;
+
 	KafkaAnnotationDrivenConfiguration(KafkaProperties properties,
 			ObjectProvider<RecordMessageConverter> messageConverter,
 			ObjectProvider<BatchMessageConverter> batchMessageConverter,
@@ -70,7 +73,8 @@ class KafkaAnnotationDrivenConfiguration {
 			ObjectProvider<KafkaAwareTransactionManager<Object, Object>> kafkaTransactionManager,
 			ObjectProvider<ErrorHandler> errorHandler,
 			ObjectProvider<BatchErrorHandler> batchErrorHandler,
-			ObjectProvider<AfterRollbackProcessor<Object, Object>> afterRollbackProcessor) {
+			ObjectProvider<AfterRollbackProcessor<Object, Object>> afterRollbackProcessor,
+			ObjectProvider<ConsumerAwareRebalanceListener> rebalanceListener) {
 		this.properties = properties;
 		this.messageConverter = messageConverter.getIfUnique();
 		this.batchMessageConverter = batchMessageConverter.getIfUnique(
@@ -80,6 +84,7 @@ class KafkaAnnotationDrivenConfiguration {
 		this.errorHandler = errorHandler.getIfUnique();
 		this.batchErrorHandler = batchErrorHandler.getIfUnique();
 		this.afterRollbackProcessor = afterRollbackProcessor.getIfUnique();
+		this.rebalanceListener = rebalanceListener.getIfUnique();
 	}
 
 	@Bean
@@ -95,6 +100,7 @@ class KafkaAnnotationDrivenConfiguration {
 		configurer.setErrorHandler(this.errorHandler);
 		configurer.setBatchErrorHandler(this.batchErrorHandler);
 		configurer.setAfterRollbackProcessor(this.afterRollbackProcessor);
+		configurer.setRebalanceListener(this.rebalanceListener);
 		return configurer;
 	}
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/kafka/KafkaAutoConfigurationTests.java

@@ -55,6 +55,7 @@ import org.springframework.kafka.core.DefaultKafkaProducerFactory;
 import org.springframework.kafka.core.KafkaAdmin;
 import org.springframework.kafka.core.KafkaTemplate;
 import org.springframework.kafka.listener.AfterRollbackProcessor;
+import org.springframework.kafka.listener.ConsumerAwareRebalanceListener;
 import org.springframework.kafka.listener.ContainerProperties;
 import org.springframework.kafka.listener.ContainerProperties.AckMode;
 import org.springframework.kafka.listener.SeekToCurrentBatchErrorHandler;
@@ -674,6 +675,18 @@ public class KafkaAutoConfigurationTests {
 				});
 	}
 
+	@Test
+	public void testConcurrentKafkaListenerContainerFactoryWithCustomRebalanceListener() {
+		this.contextRunner.withUserConfiguration(RebalanceListenerConfiguration.class)
+				.run((context) -> {
+					ConcurrentKafkaListenerContainerFactory<?, ?> factory = context
+							.getBean(ConcurrentKafkaListenerContainerFactory.class);
+					assertThat(factory.getContainerProperties())
+							.hasFieldOrPropertyWithValue("consumerRebalanceListener",
+									context.getBean("rebalanceListener"));
+				});
+	}
+
 	@Test
 	public void testConcurrentKafkaListenerContainerFactoryWithKafkaTemplate() {
 		this.contextRunner.run((context) -> {
@@ -749,6 +762,17 @@ public class KafkaAutoConfigurationTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	protected static class RebalanceListenerConfiguration {
+
+		@Bean
+		public ConsumerAwareRebalanceListener rebalanceListener() {
+			return new ConsumerAwareRebalanceListener() {
+			};
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	@EnableKafkaStreams
 	protected static class EnableKafkaStreamsConfiguration {