Question 121474 in Redis Question posted in
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Spring-Boot 2.7 Redis PUB/SUB fails startup on missing Redis connection

I have this configuration for my pub/sub implementation:

@Bean
public RedisMessageListenerContainer container(LettuceConnectionFactory connectionFactory,
                                               MessageListenerAdapter listenerAdapter) {

    RedisMessageListenerContainer container = new RedisMessageListenerContainer();
    container.setConnectionFactory(connectionFactory);
    container.addMessageListener(listenerAdapter, new ChannelTopic(publishChannel));
    return container;
}

@Bean
public MessageListenerAdapter listenerAdapter(RedisReceiver receiver) {
    return new MessageListenerAdapter(receiver, "receiveMessage");
}

@Bean
public StringRedisTemplate template(LettuceConnectionFactory connectionFactory) {
    return new StringRedisTemplate(connectionFactory);
}

This code worked fine until I updated to Spring-Boot 2.7 (previously 2.6.7).
Now this code throws the following error on startup, when my Redis is not running:

Exception encountered during context initialization – cancelling refresh attempt: org.springframework.context.ApplicationContextException: Failed to start bean ‘container‘; nested exception is org.springframework.data.redis.RedisConnectionFailureException: Unable to connect to Redis; nested exception is io.lettuce.core.RedisConnectionException: Unable to connect to localhost/:6379

("container" is the Bean at the top in my code snippet)

Where or how can I configure that it catches the thrown exception on startup and just retries it again until the connection to Redis is available?

UPDATE:

Did some digging and this part of the code is the culprit:

https://github.com/spring-projects/spring-data-redis/blob/main/src/main/java/org/springframework/data/redis/listener/RedisMessageListenerContainer.java#L1169

In comparison to the 2.6.x branch, where this was inside a try/catch (not sure though as it seems to be a completely different implementation), it is missing in version 2.7.

Tags:

2

Answers


  1. 0

    I think you have to wait for the next release, someone has fixed it and just merged into maim

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  2. 0

    It looks like the PR didn’t fix the issue in the latest release (2.7.1), it really "works as intended" to Spring team :

    Here’s my workaround:

    RedisMessageListenerContainer.Subscriber#initialize(...) method is called when adding listener to the container, so what you need is to make sure the redis connection is available first, and then add the listener to container.

    @AllArgsConstructor
public class MessageListenerSubscriber implements ApplicationListener<ApplicationReadyEvent> {

  private RedisConnectionFactory connectionFactory;
  private RedisMessageListenerContainer container;
  private MessageListener listener;
  private Collection<? extends Topic> topics;

  @Async
  @Override
  public void onApplicationEvent(ApplicationReadyEvent event) {
    var template = new RetryTemplateBuilder()
      .maxAttempts(Integer.MAX_VALUE)
      .fixedBackoff(5000)
      .build();
    template.execute(context -> {
      try {
        var connection = connectionFactory.getConnection();
        if (connection.isSubscribed()) {
          log.debug("Retrieved connection is already subscribed; aborting listening");
          return null;
        }
      } catch (Exception e) {
        log.error("Connection failure occurred. Restarting subscription task after 5000 ms");
        throw e;
      }
      this.container.addMessageListener(listener, topics);
      log.debug("Listeners registered successfully after {} retries.", context.getRetryCount());
      return null;
    });
  }
}

    and the configuration looks like:

    @Bean
public RedisMessageListenerContainer container(LettuceConnectionFactory connectionFactory) {
    RedisMessageListenerContainer container = new RedisMessageListenerContainer();
    container.setConnectionFactory(connectionFactory);
    return container;
}

@Bean
public MessageListenerAdapter listenerAdapter(RedisReceiver receiver) {
    return new MessageListenerAdapter(receiver, "receiveMessage");
}

@Bean
public MessageListenerSubscriber messageListenerSubscriber(
    RedisConnectionFactory connectionFactory,
    RedisMessageListenerContainer container,
    MessageListenerAdapter listener){
  return new MessageListenerSubscriber(
    connectionFactory,
    container,
    listener,
    List.of(new ChannelTopic(publishChannel))
  );
}
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