Merge pull request #11076 from nklmish/issue-11067

* pr/11076:
  Polish Kafka transaction support property
  Add Kafka transaction support property

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

@@ -38,6 +38,7 @@ import org.springframework.kafka.security.jaas.KafkaJaasLoginModuleInitializer;
 import org.springframework.kafka.support.LoggingProducerListener;
 import org.springframework.kafka.support.ProducerListener;
 import org.springframework.kafka.support.converter.RecordMessageConverter;
+import org.springframework.kafka.transaction.KafkaTransactionManager;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for Apache Kafka.
@@ -45,6 +46,7 @@ import org.springframework.kafka.support.converter.RecordMessageConverter;
  * @author Gary Russell
  * @author Stephane Nicoll
  * @author Eddú Meléndez
+ * @author Nakul Mishra
  * @since 1.5.0
  */
 @Configuration
@@ -94,8 +96,22 @@ public class KafkaAutoConfiguration {
 	@Bean
 	@ConditionalOnMissingBean(ProducerFactory.class)
 	public ProducerFactory<?, ?> kafkaProducerFactory() {
-		return new DefaultKafkaProducerFactory<>(
+		DefaultKafkaProducerFactory<?, ?> factory = new DefaultKafkaProducerFactory<>(
 				this.properties.buildProducerProperties());
+		String transactionIdPrefix = this.properties.getProducer()
+				.getTransactionIdPrefix();
+		if (transactionIdPrefix != null) {
+			factory.setTransactionIdPrefix(transactionIdPrefix);
+		}
+		return factory;
+	}
+
+	@Bean
+	@ConditionalOnProperty(name = "spring.kafka.producer.transaction-id-prefix")
+	@ConditionalOnMissingBean
+	public KafkaTransactionManager<?, ?> kafkaTransactionManager(
+			ProducerFactory<?, ?> producerFactory) {
+		return new KafkaTransactionManager<>(producerFactory);
 	}
 
 	@Bean

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

@@ -45,6 +45,7 @@ import org.springframework.util.CollectionUtils;
  * @author Gary Russell
  * @author Stephane Nicoll
  * @author Artem Bilan
+ * @author Nakul Mishra
  * @since 1.5.0
  */
 @ConfigurationProperties(prefix = "spring.kafka")
@@ -519,6 +520,11 @@ public class KafkaProperties {
 		 */
 		private Integer retries;
 
+		/**
+		 * When non empty, enables transaction support for producer.
+		 */
+		private String transactionIdPrefix;
+
 		/**
 		 * Additional producer-specific properties used to configure the client.
 		 */
@@ -600,6 +606,14 @@ public class KafkaProperties {
 			this.retries = retries;
 		}
 
+		public String getTransactionIdPrefix() {
+			return this.transactionIdPrefix;
+		}
+
+		public void setTransactionIdPrefix(String transactionIdPrefix) {
+			this.transactionIdPrefix = transactionIdPrefix;
+		}
+
 		public Map<String, String> getProperties() {
 			return this.properties;
 		}

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

@@ -48,6 +48,7 @@ import org.springframework.kafka.security.jaas.KafkaJaasLoginModuleInitializer;
 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.KafkaTransactionManager;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.entry;
@@ -59,6 +60,7 @@ import static org.mockito.Mockito.mock;
  * @author Gary Russell
  * @author Stephane Nicoll
  * @author Eddú Meléndez
+ * @author Nakul Mishra
  */
 public class KafkaAutoConfigurationTests {
 
@@ -198,6 +200,8 @@ public class KafkaAutoConfigurationTests {
 					assertThat(
 							context.getBeansOfType(KafkaJaasLoginModuleInitializer.class))
 									.isEmpty();
+					assertThat(context.getBeansOfType(KafkaTransactionManager.class))
+							.isEmpty();
 					assertThat(configs.get("foo.bar.baz")).isEqualTo("qux.fiz.buz");
 					assertThat(configs.get("fiz.buz")).isEqualTo("fix.fox");
 				});
@@ -256,6 +260,7 @@ public class KafkaAutoConfigurationTests {
 						"spring.kafka.listener.poll-timeout=2000",
 						"spring.kafka.listener.type=batch",
 						"spring.kafka.jaas.enabled=true",
+						"spring.kafka.producer.transaction-id-prefix=foo",
 						"spring.kafka.jaas.login-module=foo",
 						"spring.kafka.jaas.control-flag=REQUISITE",
 						"spring.kafka.jaas.options.useKeyTab=true")
@@ -297,6 +302,8 @@ public class KafkaAutoConfigurationTests {
 					assertThat(dfa.getPropertyValue("loginModule")).isEqualTo("foo");
 					assertThat(dfa.getPropertyValue("controlFlag")).isEqualTo(
 							AppConfigurationEntry.LoginModuleControlFlag.REQUISITE);
+					assertThat(context.getBeansOfType(KafkaTransactionManager.class))
+							.hasSize(1);
 					assertThat(((Map<String, String>) dfa.getPropertyValue("options")))
 							.containsExactly(entry("useKeyTab", "true"));
 				});

spring-boot-project/spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -998,6 +998,7 @@ content into your application; rather pick only the properties that you need.
 	spring.kafka.producer.ssl.keystore-password= # Store password for the key store file.
 	spring.kafka.producer.ssl.truststore-location= # Location of the trust store file.
 	spring.kafka.producer.ssl.truststore-password= # Store password for the trust store file.
+	spring.kafka.producer.transaction-id-prefix= # When non empty, enables transaction support for producer.
 	spring.kafka.producer.value-serializer= # Serializer class for values.
 	spring.kafka.properties.*= # Additional properties, common to producers and consumers, used to configure the client.
 	spring.kafka.ssl.key-password= # Password of the private key in the key store file.