Polish "Improve Kafka Auto-configuration"

Closes gh-14215

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

@@ -78,7 +78,7 @@ public class ConcurrentKafkaListenerContainerFactoryConfigurer {
 	 * Set the {@link KafkaAwareTransactionManager} to use.
 	 * @param transactionManager the transaction manager
 	 */
-	public void setTransactionManager(
+	void setTransactionManager(
 			KafkaAwareTransactionManager<Object, Object> transactionManager) {
 		this.transactionManager = transactionManager;
 	}
@@ -87,7 +87,7 @@ public class ConcurrentKafkaListenerContainerFactoryConfigurer {
 	 * Set the {@link ErrorHandler} to use.
 	 * @param errorHandler the error handler
 	 */
-	public void setErrorHandler(ErrorHandler errorHandler) {
+	void setErrorHandler(ErrorHandler errorHandler) {
 		this.errorHandler = errorHandler;
 	}
 
@@ -95,7 +95,7 @@ public class ConcurrentKafkaListenerContainerFactoryConfigurer {
 	 * Set the {@link AfterRollbackProcessor} to use.
 	 * @param afterRollbackProcessor the after rollback processor
 	 */
-	public void setAfterRollbackProcessor(
+	void setAfterRollbackProcessor(
 			AfterRollbackProcessor<Object, Object> afterRollbackProcessor) {
 		this.afterRollbackProcessor = afterRollbackProcessor;
 	}

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

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -75,8 +75,8 @@ class KafkaAnnotationDrivenConfiguration {
 		configurer.setKafkaProperties(this.properties);
 		configurer.setMessageConverter(this.messageConverter);
 		configurer.setReplyTemplate(this.kafkaTemplate);
-		configurer.setErrorHandler(this.errorHandler);
 		configurer.setTransactionManager(this.transactionManager);
+		configurer.setErrorHandler(this.errorHandler);
 		configurer.setAfterRollbackProcessor(this.afterRollbackProcessor);
 		return configurer;
 	}

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

@@ -59,6 +59,7 @@ import org.springframework.kafka.support.converter.MessagingMessageConverter;
 import org.springframework.kafka.support.converter.RecordMessageConverter;
 import org.springframework.kafka.test.utils.KafkaTestUtils;
 import org.springframework.kafka.transaction.ChainedKafkaTransactionManager;
+import org.springframework.kafka.transaction.KafkaAwareTransactionManager;
 import org.springframework.kafka.transaction.KafkaTransactionManager;
 import org.springframework.transaction.PlatformTransactionManager;
 
@@ -81,10 +82,8 @@ public class KafkaAutoConfigurationTests {
 
 	@Test
 	public void consumerProperties() {
-		this.contextRunner.withUserConfiguration(TestConfiguration.class)
-				.withPropertyValues("spring.kafka.bootstrap-servers=foo:1234",
-						"spring.kafka.properties.foo=bar",
-						"spring.kafka.properties.baz=qux",
+		this.contextRunner.withPropertyValues("spring.kafka.bootstrap-servers=foo:1234",
+				"spring.kafka.properties.foo=bar", "spring.kafka.properties.baz=qux",
 				"spring.kafka.properties.foo.bar.baz=qux.fiz.buz",
 				"spring.kafka.ssl.key-password=p1",
 				"spring.kafka.ssl.key-store-location=classpath:ksLoc",
@@ -160,20 +159,14 @@ public class KafkaAutoConfigurationTests {
 					assertThat(configs.get("baz")).isEqualTo("qux");
 					assertThat(configs.get("foo.bar.baz")).isEqualTo("qux.fiz.buz");
 					assertThat(configs.get("fiz.buz")).isEqualTo("fix.fox");
-					ConcurrentKafkaListenerContainerFactory<?, ?> factory = context
-							.getBean(ConcurrentKafkaListenerContainerFactory.class);
-					assertThat(KafkaTestUtils.getPropertyValue(factory, "errorHandler"))
-							.isSameAs(context.getBean("errorHandler"));
 				});
 	}
 
 	@Test
 	public void producerProperties() {
-		this.contextRunner.withUserConfiguration(TestConfiguration.class)
-				.withPropertyValues("spring.kafka.clientId=cid",
+		this.contextRunner.withPropertyValues("spring.kafka.clientId=cid",
 				"spring.kafka.properties.foo.bar.baz=qux.fiz.buz",
-						"spring.kafka.producer.acks=all",
-						"spring.kafka.producer.batch-size=20",
+				"spring.kafka.producer.acks=all", "spring.kafka.producer.batch-size=20",
 				"spring.kafka.producer.bootstrap-servers=bar:1234", // test
 				// override
 				"spring.kafka.producer.buffer-memory=12345",
@@ -414,7 +407,7 @@ public class KafkaAutoConfigurationTests {
 	@SuppressWarnings("unchecked")
 	@Test
 	public void listenerProperties() {
-		this.contextRunner.withUserConfiguration(TestConfiguration.class)
+		this.contextRunner
 				.withPropertyValues("spring.kafka.template.default-topic=testTopic",
 						"spring.kafka.listener.ack-mode=MANUAL",
 						"spring.kafka.listener.client-id=client",
@@ -506,7 +499,6 @@ public class KafkaAutoConfigurationTests {
 	@Test
 	public void testConcurrentKafkaListenerContainerFactoryWithCustomMessageConverters() {
 		this.contextRunner.withUserConfiguration(MessageConverterConfiguration.class)
-				.withPropertyValues("spring.kafka.producer.transaction-id-prefix=test")
 				.run((context) -> {
 					ConcurrentKafkaListenerContainerFactory<?, ?> kafkaListenerContainerFactory = context
 							.getBean(ConcurrentKafkaListenerContainerFactory.class);
@@ -514,11 +506,56 @@ public class KafkaAutoConfigurationTests {
 							kafkaListenerContainerFactory);
 					assertThat(dfa.getPropertyValue("messageConverter"))
 							.isSameAs(context.getBean("myMessageConverter"));
-					assertThat(kafkaListenerContainerFactory.getContainerProperties()
-							.getTransactionManager()).isSameAs(
-									context.getBean("chainedTransactionManager"));
+				});
+	}
+
+	@Test
+	public void testConcurrentKafkaListenerContainerFactoryWithCustomErrorHandler() {
+		this.contextRunner.withUserConfiguration(ErrorHandlerConfiguration.class)
+				.run((context) -> {
+					ConcurrentKafkaListenerContainerFactory<?, ?> factory = context
+							.getBean(ConcurrentKafkaListenerContainerFactory.class);
+					assertThat(KafkaTestUtils.getPropertyValue(factory, "errorHandler"))
+							.isSameAs(context.getBean("errorHandler"));
+				});
+	}
+
+	@Test
+	public void testConcurrentKafkaListenerContainerFactoryWithDefaultTransactionManager() {
+		this.contextRunner
+				.withPropertyValues("spring.kafka.producer.transaction-id-prefix=test")
+				.run((context) -> {
+					assertThat(context).hasSingleBean(KafkaAwareTransactionManager.class);
+					ConcurrentKafkaListenerContainerFactory<?, ?> factory = context
+							.getBean(ConcurrentKafkaListenerContainerFactory.class);
+					assertThat(factory.getContainerProperties().getTransactionManager())
+							.isSameAs(
+									context.getBean(KafkaAwareTransactionManager.class));
+				});
+	}
+
+	@Test
+	public void testConcurrentKafkaListenerContainerFactoryWithCustomTransactionManager() {
+		this.contextRunner.withUserConfiguration(TransactionManagerConfiguration.class)
+				.withPropertyValues("spring.kafka.producer.transaction-id-prefix=test")
+				.run((context) -> {
+					ConcurrentKafkaListenerContainerFactory<?, ?> factory = context
+							.getBean(ConcurrentKafkaListenerContainerFactory.class);
+					assertThat(factory.getContainerProperties().getTransactionManager())
+							.isSameAs(context.getBean("chainedTransactionManager"));
+				});
+	}
+
+	@Test
+	public void testConcurrentKafkaListenerContainerFactoryWithCustomAfterRollbackProcessor() {
+		this.contextRunner
+				.withUserConfiguration(AfterRollbackProcessorConfiguration.class)
+				.run((context) -> {
+					ConcurrentKafkaListenerContainerFactory<?, ?> factory = context
+							.getBean(ConcurrentKafkaListenerContainerFactory.class);
+					DirectFieldAccessor dfa = new DirectFieldAccessor(factory);
 					assertThat(dfa.getPropertyValue("afterRollbackProcessor"))
-							.isSameAs(context.getBean("arp"));
+							.isSameAs(context.getBean("afterRollbackProcessor"));
 				});
 	}
 
@@ -535,34 +572,43 @@ public class KafkaAutoConfigurationTests {
 	}
 
 	@Configuration
-	protected static class TestConfiguration {
+	protected static class MessageConverterConfiguration {
 
 		@Bean
-		public SeekToCurrentErrorHandler errorHandler() {
-			return new SeekToCurrentErrorHandler();
+		public RecordMessageConverter myMessageConverter() {
+			return mock(RecordMessageConverter.class);
 		}
 
 	}
 
 	@Configuration
-	protected static class MessageConverterConfiguration {
+	protected static class ErrorHandlerConfiguration {
 
 		@Bean
-		public RecordMessageConverter myMessageConverter() {
-			return mock(RecordMessageConverter.class);
+		public SeekToCurrentErrorHandler errorHandler() {
+			return new SeekToCurrentErrorHandler();
+		}
+
 	}
 
+	@Configuration
+	protected static class TransactionManagerConfiguration {
+
 		@Bean
 		@Primary
 		public PlatformTransactionManager chainedTransactionManager(
 				KafkaTransactionManager<String, String> kafkaTransactionManager) {
-
 			return new ChainedKafkaTransactionManager<String, String>(
 					kafkaTransactionManager);
 		}
 
+	}
+
+	@Configuration
+	protected static class AfterRollbackProcessorConfiguration {
+
 		@Bean
-		public AfterRollbackProcessor<Object, Object> arp() {
+		public AfterRollbackProcessor<Object, Object> afterRollbackProcessor() {
 			return (records, consumer, ex, recoverable) -> {
 				// no-op
 			};

spring-boot-project/spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -5628,18 +5628,6 @@ When the Apache Kafka infrastructure is present, any bean can be annotated with
 `@KafkaListener` to create a listener endpoint. If no `KafkaListenerContainerFactory` has
 been defined, a default one is automatically configured with keys defined in
 `spring.kafka.listener.*`.
-If the property `spring.kafka.producer.transaction-id-prefix` is defined, a
-`KafkaTransactionManager` will be auto-configured with name `kafkaTransactionManager` and
-will be wired into the container factory.
-Also, if `RecordMessageConverter`, `ErrorHandler` and/or
-`AfterRollbackProcessor` beans are defined, they are automatically associated to the
-default factory.
-
-IMPORTANT: The auto configuration of these beans occur if there is just a single
-instance.
-When using a `ChainedKafkaTransactionManager`, it will usually reference the configured
-`KafkaTransactionManager` bean, so the chained manager must be marked
-`@Primary` if you want it wired into the container factory.
 
 The following component creates a listener endpoint on the `someTopic` topic:
 
@@ -5656,6 +5644,16 @@ The following component creates a listener endpoint on the `someTopic` topic:
 	}
 ----
 
+If a `KafkaTransactionManager` bean is defined, it is automatically associated to the
+container factory. Similarly, if a `RecordMessageConverter`, `ErrorHandler` or
+`AfterRollbackProcessor` bean is defined, it is automatically associated to the default
+factory.
+
+TIP: A custom `ChainedKafkaTransactionManager` must be marked `@Primary` as it usually
+reference the auto-configured `KafkaTransactionManager` bean.
+
+
+
 [[boot-features-kafka-streams]]
 ==== Kafka Streams
 Spring for Apache Kafka provides a factory bean to create a `StreamsBuilder` object and