Unable to set serde, producer and consumer properties per topic/binder level in spring cloud kafka - apache-kafka

Question

I'm trying to bring up simple pub-sub application using spring cloud kafka binder. However I'm unable to set Serializer, DeSerialzer property and other producer and consumer properties in application.yml. I consistently get serialization/deserialization error. Even kafka logs in spring boot project shows producer and consumer config still users ByteArraySerializer. Below is the code sameple.
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.2.4.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>io.github.kprasad99.kafka</groupId>
<artifactId>kp-kafka-streams-example</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>kp-kafka-streams-example</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>11</java.version>
<spring-cloud.version>Hoxton.SR1</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- <dependency>
<groupId>org.apache.kafka</groupId>
<artifactId>kafka-streams</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-stream</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-stream-binder-kafka-streams</artifactId>
</dependency> -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-stream-binder-kafka</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.kafka</groupId>
<artifactId>spring-kafka</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-stream</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-configuration-processor</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-stream-test-support</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
Processor.java
public interface Processor {
String INPUT="k-msg-source";
String OUTPUT="k-msg-sink";
#Input(INPUT)
SubscribableChannel input();
#Output(OUTPUT)
MessageChannel output();
}
KRest.java
#RestController
public class KRest {
#Autowired
private Processor processor;
#GetMapping("/send")
public ResponseEntity<Void> send(#RequestParam("key")String key, #RequestParam("msg") String text){
processor.input().send(MessageBuilder.withPayload(Message.builder().text(text).build()).setHeader(KafkaHeaders.MESSAGE_KEY, key).build());
return ResponseEntity.ok().build();
}
}
Message.java
#Data
#NoArgsConstructor
#AllArgsConstructor
#Builder
public class Message {
private String text;
}
And finally application.yml
spring:
cloud:
stream:
bindings:
k-msg-source:
binder: kafka
content-type: application/json
destination: topic.kp.msg
group: kp.msg.source
k-msg-sink:
binder: kafka
content-type: application/json
destination: topic.kp.msg
group: kp.msg.sink
producer:
partition-count: 10
binders:
kafka:
type: kafka
environment:
spring.cloud.stream.kafka.binder:
brokers: localhost:9092
configuration:
value.serde: JsonSerde
key.serde: StringSerde
producer:
value.serde: JsonSerde
key.serde: StringSerde
replication-factor: 1
Versions
spring-boot: 2.2.4
spring-cloud: Hoxton.SR1
spring-cloud-stream-kafka-binder: 3.0.1

Answer 1

Serdes are used by the Kafka Streams binder.
With the MessageChannel binder, the properties are value.serializer and value.deserializer (and key...), and key/value.deserializer.
You also have to specify the fully qualified named of the classes.

Answer 2

Final application.yml
spring.cloud.stream:
bindings:
k-msg-source:
binder: kafka
destination: topic.kp.msg
content-type: application/json
producer:
partition-count: 10
use-native-encoding: true
k-msg-sink:
binder: kafka
destination: topic.kp.msg
group: ne-publisher
content-type: application/json
consumer:
use-native-decoding: true
binders:
kafka:
type: kafka
environment:
spring.cloud.stream.kafka.binder:
brokers: PLAINTEXT://localhost:19092,PLAINTEXT://localhost:29092,PLAINTEXT://localhost:39092
configuration:
key.serializer: org.apache.kafka.common.serialization.StringSerializer
value.serializer: org.springframework.kafka.support.serializer.JsonSerializer
key.deserializer: org.apache.kafka.common.serialization.StringDeserializer
value.deserializer: org.springframework.kafka.support.serializer.JsonDeserializer
consumer-properties:
spring.json.trusted.packages: "*"