Send message in specific partition of Topic

Question

Is there any way producer could send messages to specific partiton of topic in broker ?

As of now, am able to send topic having 2 partitions, but dont have control to send in specific partition.

Component
@EnableBinding(Source.class)
public class RsvpsKafkaProducer {
  
    private static final int SENDING_MESSAGE_TIMEOUT_MS = 10000;

    private final Source source;

    public RsvpsKafkaProducer(Source source) {
        this.source = source;
    }

    public void sendRsvpMessage(WebSocketMessage<?> message) {
        
         System.out.println("sendRsvpMessage");
         source.output()
                .send(MessageBuilder.withPayload(message.getPayload())
                        .build(),
                        SENDING_MESSAGE_TIMEOUT_MS);   
    }
}

application.properties

spring.cloud.stream.kafka.binder.zkNodes=localhost:2181
spring.cloud.stream.kafka.binder.brokers=localhost:9093

spring.cloud.stream.bindings.output.destination=meetupTopic
spring.cloud.stream.bindings.output.producer.partitionCount=2

spring.cloud.stream.bindings.output.content-type=text/plain
spring.cloud.stream.bindings.output.producer.headerMode=raw

Is there any way I could achieve it using spring cloud stream ? I want some messages to go in P1 partition and some to P2 partition within meetupTopic .

Answer 1

MessageBuilder.withPayload(message.getPayload())
                        .setHeader(KafkaHeaders.PARTITION_ID, 23)
                        .build()

Answer 2

I haven't tried this but from the docs , it looks like it might work.

spring.cloud.stream.bindings.output.producer.partitionSelectorExpression=headers['partitionKey']

And then you add the header partitionKey when you send the message.