EmbeddedKafkaKraftBroker.kafkaPorts(int... ports) is ignored

[zyro23]

First of all, thanks for the new EmbeddedKafkaBroker abstraction and the KRaft impl.!

In what version(s) of Spring for Apache Kafka are you seeing this issue?

3.1.0

Describe the bug

EmbeddedKafkaKraftBroker.kafkaPorts(int... ports) sets the kafkaPorts array but it seems that is never used?

ref.: https://github.com/spring-projects/spring-kafka/blob/v3.1.0/spring-kafka-test/src/main/java/org/springframework/kafka/test/EmbeddedKafkaKraftBroker.java#L148-L160

To Reproduce

EmbeddedKafkaKraftBroker broker = new EmbeddedKafkaKraftBroker(1,1)
    .kafkaPorts(9092);

-> still uses random port.

Expected behavior

The EmbeddedKafkaKraftBroker actually uses the specified port(s).

Sample

ping me if you think a sample is helpful here.

[sobychacko]

@zyro23 Currently, it is not possible to propagate custom ports in KafkaClusterTestKit. We just documented this via javadocs.

[sobychacko]

I asked the broader Apache Kafka community this question here. If we have an update, we can revisit this issue and open it again.

[garyrussell]

For the record, it is not good practice to hard code the port used in tests. It can cause conflicts when multiple test run concurrently on the same machine.

[zyro23]

For the record, it is not good practice to hard code the port used in tests. It can cause conflicts when multiple test run concurrently on the same machine.

fully agreed - as far as tests are concerned (happy with EmbeddedKafkaKraftBroker & random port(s)).

however, we are also using EmbeddedKafkaZKBroker with static/configured ports at runtime for local development (providing an embedded alternative to an external/containerized broker).
would be great to be able to use EmbeddedKafkaKraftBroker for that scenario, too :)

[sp193]

If we aren't recommended to hardcode the port, how can we get the broker address for Kafka client configuration when not using the default Spring Boot Kafka configuration classes? I have my own configuration classes to configure Kafka, as we may retrieve the Kafka settings and secrets from 3rd party services.

There seems to be a spring.embedded.kafka.brokers property and I assume it gets set at some point, but it does not seem to get set when it is needed. I guess that it's not getting set in time, due to my configuration class getting instantiated before the embedded broker is configured. But I cannot find a way to get this configuration in time, without making spring-kafka-test a dependency.

I am trying to keep the test dependencies out of the release builds. Could you please advise me on how I can elegantly achieve such a thing?

Thanks in advance.