How to skip corrupt (non-serializable) messages in Spring Kafka Consumer?

Question

This question is for Spring Kafka, related to Apache Kafka with High Level Consumer: Skip corrupted messages

Is there a way to configure Spring Kafka consumer to ski

Answer 1

You need ErrorHandlingDeserializer: https://docs.spring.io/spring-kafka/docs/2.2.0.RELEASE/reference/html/_reference.html#error-handling-deserializer

If you can't move to that 2.2 version, consider to implement your own and return null for those records which can't be deserialized properly.

The source code is here: https://github.com/spring-projects/spring-kafka/blob/master/spring-kafka/src/main/java/org/springframework/kafka/support/serializer/ErrorHandlingDeserializer2.java

Answer 2

In case you are using older version of kafka, in a @KafkaListener set the following Consumer factory configurations.

 Map<String, Object> props = new HashMap<>();
    props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
    props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
    props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, CustomDeserializer.class);

Here is the code for CustomDeserializer:

 import java.util.Map;
    import org.apache.kafka.common.serialization.Deserializer;
    import com.fasterxml.jackson.databind.ObjectMapper;
    public class CustomDeserializer implements Deserializer<Object>
    {
        @Override
        public void configure( Map<String, ?> configs, boolean isKey )
        {
        }

        @Override
        public Object deserialize( String topic, byte[] data )
        {
            ObjectMapper mapper = new ObjectMapper();
            Object object = null;
            try
            {
                object = mapper.readValue(data, Object.class);
            }
            catch ( Exception exception )
            {
                System.out.println("Error in deserializing bytes " + exception);
            }
            return object;
        }

        @Override
        public void close()
        {
        }
    }

Since I want my code to be generic enough to read any kind of json, object = mapper.readValue(data, Object.class); I am converting it to Object.class. And as we are catching exception here, it won't be retried once read.