Spring cloud stream + spring retry, How to add recovery callback and disable logic that send to DLQ? - spring-cloud

Question

I'm using spring cloud stream + rabbit mq binder.
In my #StreaListener I want to apply retry logic on specific exceptions using RetryTemplate. After retries are exhausted or not retriable error is thrown, I would like to add a recovery callback that will save a new record with an error message to my Postgres DB and finish with the message (move to the next).
Here what I got so far:
#StreamListener(Sink.INPUT)
public void saveUser(User user) {
User user = userService.saveUser(user); //could throw exceptions
log.info(">>>>>>User is created successfully: {}", user);
}
#StreamRetryTemplate
public RetryTemplate myRetryTemplate() {
RetryTemplate retryTemplate = new RetryTemplate();
retryTemplate.setBackOffPolicy(new ExponentialBackOffPolicy());
Map<Class<? extends Throwable>, Boolean> retryableExceptions = new HashMap<>();
retryableExceptions.put(ConnectionException.class, true);
retryTemplate.registerListener(new RetryListener() {
#Override
public <T, E extends Throwable> boolean open(RetryContext context,
RetryCallback<T, E> callback) {
return true;
}
#Override
public <T, E extends Throwable> void close(RetryContext context, RetryCallback<T, E> callback,
Throwable throwable) {
//could add recovery logic here, like save error to db why sertain user was not saved
log.info("retries exausted");
}
#Override
public <T, E extends Throwable> void onError(RetryContext context,
RetryCallback<T, E> callback, Throwable throwable) {
log.error("Error on retry", throwable);
}
});
retryTemplate.setRetryPolicy(
new SimpleRetryPolicy(properties.getRetriesCount(), retryableExceptions, true));
return retryTemplate;
}
from properties, I only have these (no any dlq configuration)
spring.cloud.stream.bindings.input.destination = user-topic
spring.cloud.stream.bindings.input.group = user-consumer
And after retries are exhausted I get this log.
2020-06-01 20:05:58.674 INFO 18524 --- [idge-consumer-1] o.s.a.r.c.CachingConnectionFactory : Attempting to connect to: [localhost:56722]
2020-06-01 20:05:58.685 INFO 18524 --- [idge-consumer-1] o.s.a.r.c.CachingConnectionFactory : Created new connection: rabbitConnectionFactory.publisher#319c51b0:0/SimpleConnection#2a060201 [delegate=amqp://guest#127.0.0.1:56722/, localPort= 50728]
2020-06-01 20:05:58.697 INFO 18524 --- [idge-consumer-1] c.e.i.o.b.c.RetryConfiguration : retry finish
2020-06-01 20:05:58.702 ERROR 18524 --- [127.0.0.1:56722] o.s.a.r.c.CachingConnectionFactory : Channel shutdown: channel error; protocol method: #method<channel.close>(reply-code=404, reply-text=NOT_FOUND - no exchange 'DLX' in vhost '/', class-id=60, method-id=40)
After RetryListener close method triggered, I can see that listener tries to connect to DLX probably to publish an error message. And I don't want it to do that as well as observe this error message in the log each time.
So my questions are:
1) Where to add RecoveryCalback for my retryTemplate? Supposedly I could write my recover logic with saving error to db in RetryListener#close method, but there definetely should be more appropriate way to do that.
2) How to configure rabbit-mq binder not to send messages to DLQ, maybe I could override some method? Currently, after retries are exhausted (or not retriable error is coming) listener tries to send a message to DLX and logs error that couldn't find it. I don't need any messages to be sent to dlq in scope of my application, I only need to save it to DB.

Answer 1

There is currently no mechanism to provision a custom recovery callback.
Set republishToDlq to false (it used to be). It was changed to true, which is wrong if autoBindDlq is false (default); I will open an issue for that.
Then, when retries are exhausted, the exception will be thrown back to the container; you can use a ListenerContainerCustomizer to add a custom ErrorHandler.
However, the data you get there will be a ListenerExecutionFailed exception with the raw (unconverted) Spring AMQP Message in its failedMessage property, not your User object.
EDIT
You can add a listener to the binding's error channel...
#SpringBootApplication
#EnableBinding(Sink.class)
public class So62137618Application {
public static void main(String[] args) {
SpringApplication.run(So62137618Application.class, args);
}
#StreamListener(Sink.INPUT)
public void listen(String in) {
System.out.println(in);
throw new RuntimeException("test");
}
#ServiceActivator(inputChannel = "user-topic.user-consumer.errors")
public void errors(String in) {
System.out.println("Retries exhausted for " + new String((byte[]) in.getFailedMessage().getPayload()));
}
}