spring Kafka listening to regex

Question

I am trying to listen newly created topic with the below code, but is not working. Can you please tell me if the below code is correct?

public class KafkaMessageListener {
    private static final Logger LOGGER = LoggerFactory.getLogger(KafkaMessageListener.class);

    private final ProcessEventModel eventModel;

    @KafkaListener(topicPattern = "betsyncDataTopic*")
    public void receive(ConsumerRecord<String, String> consumerRecord) {
        LOGGER.info("received payload at '{}'", consumerRecord.timestamp());
        eventModel.process(consumerRecord.value());
    }

Answer 1

Your regex is not valid; it should be betsyncDataTopic.*.

@KafkaListener(id = "xxx", topicPattern = "kbgh.*")
public void listen(String in) {
    System.out.println(in);
}

...

partitions assigned: [kbgh290-0]

EDIT

If you later add new topics that match the pattern, there will be a delay before the rebalance. According to the KafkaConsumer javadocs...

 * Subscribe to all topics matching specified pattern to get dynamically assigned partitions.
 * The pattern matching will be done periodically against topic existing at the time of check.
 * <p>
 * As part of group management, the consumer will keep track of the list of consumers that
 * belong to a particular group and will trigger a rebalance operation if one of the
 * following events trigger -
 * <ul>
 * <li>Number of partitions change for any of the subscribed list of topics
 * <li>Topic is created or deleted
 * <li>An existing member of the consumer group dies
 * <li>A new member is added to an existing consumer group via the join API
 * </ul>

I just ran a test; added a new matching topic at 12:13:32; result:

2018-02-12 12:17:30.394  INFO 88028 --- [      xxx-0-C-1] o.s.k.l.KafkaMessageListenerContainer    
: partitions revoked: [kbgh290-0]
2018-02-12 12:17:30.450  INFO 88028 --- [      xxx-0-C-1] o.s.k.l.KafkaMessageListenerContainer    
: partitions assigned: [kbgh290-0, kbghNew-0]

So it takes 5 minutes, by default.

https://kafka.apache.org/documentation/#consumerconfigs_metadata.max.age.ms

The period of time in milliseconds after which we force a refresh of metadata even if we haven't seen any partition leadership changes to proactively discover any new brokers or partitions.