🧵 Struggling with custom exponential retries in your Spring Boot Kafka application? Here’s a quick guide to get it working! 🚀

1/7 🌱 Dependency Setup:
Ensure you have the necessary dependencies in your pom.xml or build.gradle. You need spring-kafka and spring-retry.

<dependency>
    <groupId>org.springframework.kafka</groupId>
    <artifactId>spring-kafka</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.retry</groupId>
    <artifactId>spring-retry</artifactId>
</dependency>

2/7 🛠️ Configuration:
Create a Kafka configuration class to set up retry policies. Use RetryTemplate for exponential backoff.

@Configuration
public class KafkaConfig {

    @Bean
    public RetryTemplate retryTemplate() {
        RetryTemplate retryTemplate = new RetryTemplate();

        FixedBackOffPolicy backOffPolicy = new FixedBackOffPolicy();
        backOffPolicy.setBackOffPeriod(1000); // initial interval

        retryTemplate.setBackOffPolicy(backOffPolicy);
        retryTemplate.setRetryPolicy(new SimpleRetryPolicy(3)); // max attempts

        return retryTemplate;
    }
}

3/7 🔄 Exponential Backoff Policy:
For exponential backoff, use ExponentialBackOffPolicy.

@Bean
public RetryTemplate retryTemplate() {
    RetryTemplate retryTemplate = new RetryTemplate();

    ExponentialBackOffPolicy backOffPolicy = new ExponentialBackOffPolicy();
    backOffPolicy.setInitialInterval(1000);
    backOffPolicy.setMaxInterval(10000);
    backOffPolicy.setMultiplier(2);

    retryTemplate.setBackOffPolicy(backOffPolicy);
    retryTemplate.setRetryPolicy(new SimpleRetryPolicy(3));

    return retryTemplate;
}

4/7 📥 Consumer Factory:
Integrate the RetryTemplate with your Kafka consumer factory.

@Bean
public ConcurrentKafkaListenerContainerFactory<String, String> kafkaListenerContainerFactory() {
    ConcurrentKafkaListenerContainerFactory<String, String> factory =
        new ConcurrentKafkaListenerContainerFactory<>();
    factory.setConsumerFactory(consumerFactory());
    factory.setRetryTemplate(retryTemplate());
    return factory;
}

5/7 🏗️ Consumer Factory Method:
Define the consumer factory method as well.

@Bean
public ConsumerFactory<String, String> consumerFactory() {
    Map<String, Object> props = new HashMap<>();
    props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
    props.put(ConsumerConfig.GROUP_ID_CONFIG, "group_id");
    props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
    props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
    return new DefaultKafkaConsumerFactory<>(props);
}

6/7 🎧 Listener:
Ensure your listener is configured properly to handle retries.

@KafkaListener(topics = "topic_name", groupId = "group_id")
public void listen(String message) {
    // Your message handling logic
    System.out.println("Received message: " + message);
    // Simulate error for retry
    if (message.equals("retry")) {
        throw new RuntimeException("Simulated error");
    }
}

7/7 🎉 Wrap Up:
With these configurations, your Spring Boot Kafka application should now properly handle custom exponential retries.

How to Implement Custom Exponential Retry in Spring Boot with Kafka