Support arbitrary Kafka properties

Add support for arbitrary Kafka properties via
`spring.kafka.properties.*` and also a `spring.kafka.max.poll.records`
property.

See gh-7672

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

@@ -71,6 +71,11 @@ public class KafkaProperties {
 	 */
 	private String clientId;
 
+	/**
+	 * Additional properties used to configure the client.
+	 */
+	private Map<String, String> properties = new HashMap<String, String>();
+
 	public Consumer getConsumer() {
 		return this.consumer;
 	}
@@ -107,6 +112,14 @@ public class KafkaProperties {
 		this.clientId = clientId;
 	}
 
+	public Map<String, String> getProperties() {
+		return this.properties;
+	}
+
+	public void setProperties(Map<String, String> properties) {
+		this.properties = properties;
+	}
+
 	private Map<String, Object> buildCommonProperties() {
 		Map<String, Object> properties = new HashMap<String, Object>();
 		if (this.bootstrapServers != null) {
@@ -135,6 +148,9 @@ public class KafkaProperties {
 			properties.put(SslConfigs.SSL_TRUSTSTORE_PASSWORD_CONFIG,
 					this.ssl.getTruststorePassword());
 		}
+		if (this.properties != null && this.properties.size() > 0) {
+			properties.putAll(this.properties);
+		}
 		return properties;
 	}
 
@@ -240,6 +256,11 @@ public class KafkaProperties {
 		 */
 		private Class<?> valueDeserializer = StringDeserializer.class;
 
+		/**
+		 * Maximum number of records returned in a single call to poll().
+		 */
+		private Integer maxPollRecords;
+
 		public Ssl getSsl() {
 			return this.ssl;
 		}
@@ -332,6 +353,14 @@ public class KafkaProperties {
 			this.valueDeserializer = valueDeserializer;
 		}
 
+		public Integer getMaxPollRecords() {
+			return this.maxPollRecords;
+		}
+
+		public void setMaxPollRecords(Integer maxPollRecords) {
+			this.maxPollRecords = maxPollRecords;
+		}
+
 		public Map<String, Object> buildProperties() {
 			Map<String, Object> properties = new HashMap<String, Object>();
 			if (this.autoCommitInterval != null) {
@@ -395,6 +424,9 @@ public class KafkaProperties {
 				properties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG,
 						this.valueDeserializer);
 			}
+			if (this.maxPollRecords != null) {
+				properties.put(ConsumerConfig.MAX_POLL_RECORDS_CONFIG, this.maxPollRecords);
+			}
 			return properties;
 		}
 

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

@@ -61,12 +61,16 @@ public class KafkaAutoConfigurationTests {
 	@Test
 	public void consumerProperties() {
 		load("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.keystore-location=classpath:ksLoc",
 				"spring.kafka.ssl.keystore-password=p2",
 				"spring.kafka.ssl.truststore-location=classpath:tsLoc",
 				"spring.kafka.ssl.truststore-password=p3",
 				"spring.kafka.consumer.auto-commit-interval=123",
+				"spring.kafka.consumer.max-poll-records=42",
 				"spring.kafka.consumer.auto-offset-reset=earliest",
 				"spring.kafka.consumer.client-id=ccid", // test override common
 				"spring.kafka.consumer.enable-auto-commit=false",
@@ -109,6 +113,11 @@ public class KafkaAutoConfigurationTests {
 				.isEqualTo(LongDeserializer.class);
 		assertThat(configs.get(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG))
 				.isEqualTo(IntegerDeserializer.class);
+		assertThat(configs.get(ConsumerConfig.MAX_POLL_RECORDS_CONFIG))
+				.isEqualTo(42);
+		assertThat(configs.get("foo")).isEqualTo("bar");
+		assertThat(configs.get("baz")).isEqualTo("qux");
+		assertThat(configs.get("foo.bar.baz")).isEqualTo("qux.fiz.buz");
 	}
 
 	@Test

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

@@ -878,6 +878,7 @@ content into your application; rather pick only the properties that you need.
 	spring.kafka.consumer.group-id= # Unique string that identifies the consumer group this consumer belongs to.
 	spring.kafka.consumer.heartbeat-interval= # Expected time in milliseconds between heartbeats to the consumer coordinator.
 	spring.kafka.consumer.key-deserializer= # Deserializer class for keys.
+	spring.kafka.consumer.max-poll-messages= # Maximum number of records returned in a single call to poll().
 	spring.kafka.consumer.value-deserializer= # Deserializer class for values.
 	spring.kafka.listener.ack-count= # Number of records between offset commits when ackMode is "COUNT" or "COUNT_TIME".
 	spring.kafka.listener.ack-mode= # Listener AckMode; see the spring-kafka documentation.
@@ -893,6 +894,7 @@ content into your application; rather pick only the properties that you need.
 	spring.kafka.producer.key-serializer= # Serializer class for keys.
 	spring.kafka.producer.retries= # When greater than zero, enables retrying of failed sends.
 	spring.kafka.producer.value-serializer= # Serializer class for values.
+	spring.kafka.properties.*= # Additional properties used to configure the client.
 	spring.kafka.ssl.key-password= # Password of the private key in the key store file.
 	spring.kafka.ssl.keystore-location= # Location of the key store file.
 	spring.kafka.ssl.keystore-password= # Store password for the key store file.

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

@@ -4643,22 +4643,22 @@ auto configuration supports all HIGH importance properties, some selected MEDIUM
 and any that do not have a default value.
 
 Only a subset of the properties supported by Kafka are available via the `KafkaProperties`
-class. If you wish to configure the producer or consumer with additional properties, you
-can override the producer factory and/or consumer factory bean, adding additional
-properties, for example:
+class. If you wish to configure the producer or consumer with additional properties that
+are not directly supported, use the following:
+
+`spring.kafka.properties.foo.bar=baz`
+
+This sets the common `foo.bar` kafka property to `baz`.
+
+These properties will be shared by both the consumer and producer factory beans.
+If you wish to customize these components with different properties, such as to use a
+different metrics reader for each, you can override the bean definitions, as follows:
 
 [source,java,indent=0]
 ----
-	@Bean
-	public ProducerFactory<?, ?> kafkaProducerFactory(KafkaProperties properties) {
-		Map<String, Object> producerProperties = properties.buildProducerProperties();
-		producerProperties.put("some.property", "some.value");
-		return new DefaultKafkaProducerFactory<Object, Object>(producerProperties);
-	}
+include::{code-examples}/kafka/KafkaSpecialProducerConsumerConfigExample.java[tag=configuration]
 ----
 
-
-
 [[boot-features-restclient]]
 == Calling REST services
 If you need to call remote REST services from your application, you can use Spring

spring-boot-docs/src/main/java/org/springframework/boot/kafka/KafkaSpecialProducerConsumerConfigExample.java

@@ -0,0 +1,125 @@
+/*
+ * Copyright 2016-2016 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.kafka;
+
+import java.util.List;
+import java.util.Map;
+
+import org.apache.kafka.clients.CommonClientConfigs;
+import org.apache.kafka.common.metrics.KafkaMetric;
+import org.apache.kafka.common.metrics.MetricsReporter;
+
+import org.springframework.boot.autoconfigure.kafka.KafkaProperties;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.kafka.core.ConsumerFactory;
+import org.springframework.kafka.core.DefaultKafkaConsumerFactory;
+import org.springframework.kafka.core.DefaultKafkaProducerFactory;
+import org.springframework.kafka.core.ProducerFactory;
+
+/**
+ * Example custom kafka configuration beans used when the user wants to
+ * apply different common properties to the producer and consumer.
+ *
+ * @author Gary Russell
+ * @since 1.5
+ *
+ */
+public class KafkaSpecialProducerConsumerConfigExample {
+
+	// tag::configuration[]
+	@Configuration
+	public static class CustomKafkaBeans {
+
+		/**
+		 * Customized ProducerFactory bean.
+		 * @param properties the kafka properties.
+		 * @return the bean.
+		 */
+		@Bean
+		public ProducerFactory<?, ?> kafkaProducerFactory(KafkaProperties properties) {
+			Map<String, Object> producerProperties = properties.buildProducerProperties();
+			producerProperties.put(CommonClientConfigs.METRIC_REPORTER_CLASSES_CONFIG,
+					MyProducerMetricsReporter.class);
+			return new DefaultKafkaProducerFactory<Object, Object>(producerProperties);
+		}
+
+		/**
+		 * Customized ConsumerFactory bean.
+		 * @param properties the kafka properties.
+		 * @return the bean.
+		 */
+		@Bean
+		public ConsumerFactory<?, ?> kafkaConsumerFactory(KafkaProperties properties) {
+			Map<String, Object> consumererProperties = properties.buildConsumerProperties();
+			consumererProperties.put(CommonClientConfigs.METRIC_REPORTER_CLASSES_CONFIG,
+					MyConsumerMetricsReporter.class);
+			return new DefaultKafkaConsumerFactory<Object, Object>(consumererProperties);
+		}
+
+	}
+	// end::configuration[]
+
+	public static class MyConsumerMetricsReporter implements MetricsReporter {
+
+		@Override
+		public void configure(Map<String, ?> configs) {
+		}
+
+		@Override
+		public void init(List<KafkaMetric> metrics) {
+		}
+
+		@Override
+		public void metricChange(KafkaMetric metric) {
+		}
+
+		@Override
+		public void metricRemoval(KafkaMetric metric) {
+		}
+
+		@Override
+		public void close() {
+		}
+
+	}
+
+	public static class MyProducerMetricsReporter implements MetricsReporter {
+
+		@Override
+		public void configure(Map<String, ?> configs) {
+		}
+
+		@Override
+		public void init(List<KafkaMetric> metrics) {
+		}
+
+		@Override
+		public void metricChange(KafkaMetric metric) {
+		}
+
+		@Override
+		public void metricRemoval(KafkaMetric metric) {
+		}
+
+		@Override
+		public void close() {
+		}
+
+	}
+
+}