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ClassCastException on attempt to get bootstrap server from SenderOption/ReceiverOptions #374

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ajax-osadchuk-r opened this issue Dec 8, 2023 · 3 comments · Fixed by #376
Closed

ClassCastException on attempt to get bootstrap server from SenderOption/ReceiverOptions #374

ajax-osadchuk-r opened this issue Dec 8, 2023 · 3 comments · Fixed by #376
Labels
type/bug A general bug
Milestone
1.3.23

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@ajax-osadchuk-r
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ajax-osadchuk-r commented Dec 8, 2023 •
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Expected Behavior

SenderOptions#bootstrapServers and ReceiverOptions#bootstrapServers should sucessffully return bootstrap.servers config property value

Actual Behavior

SenderOptions#bootstrapServers and ReceiverOptions#bootstrapServers throw next ClassCastException:

java.lang.ClassCastException: class java.util.ArrayList cannot be cast to class java.lang.String (java.util.ArrayList and java.lang.String are in module java.base of loader 'bootstrap')
        at reactor.kafka.sender.SenderOptions.bootstrapServers(SenderOptions.java:289)
        
//------------------------------------------------------------------------------------------------------------------

java.lang.ClassCastException: class java.util.ArrayList cannot be cast to class java.lang.String (java.util.ArrayList and java.lang.String are in module java.base of loader 'bootstrap')
        at reactor.kafka.receiver.ReceiverOptions.bootstrapServers(ReceiverOptions.java:573)

that is because SenderOptions#producerProperty returns an instance of Object class, in case of BOOTSTRAP_SERVERS_CONFIG it is an object of List and it can not be casted to a String
image

Steps to Reproduce

@Test
void reproCase() {
        var kafkaProps =  new KafkaProperties();
        var senderOptions = SenderOptions.create(kafkaProps.buildProducerProperties());
        assertThrows(ClassCastException.class, senderOptions::bootstrapServers);

        var receiverOptions = ReceiverOptions.create(kafkaProps.buildConsumerProperties());
        assertThrows(ClassCastException.class, receiverOptions::bootstrapServers);
}

Possible Solution

Your Environment

  • Reactor version(s) used: reactor-kafka:1.3.22, reactor-core:3.5.12
  • Other relevant libraries versions (eg. netty, ...):
  • JVM version (java -version): 18
  • OS and version (eg uname -a): MacOS 13.4
@reactorbot reactorbot added the ❓need-triage This issue needs triage, hasn't been looked at by a team member yet label Dec 8, 2023
@sanderino666
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As a workaround, I did this:

Map<String, Object> props = kafkaProperties.buildProducerProperties(null);

//reactor-kafka 1.3.22 casts the given bootstrap servers arraylist to a string and throws a class cast exception
//https://github.com/reactor/reactor-kafka/issues/374
props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, String.join(",", kafkaProperties.getProducer().getBootstrapServers()));

SenderOptions<String, CloudEvent> senderOptions = SenderOptions.create(props);
...

This is an example for the producer side, the same holds for the consumer side.

kafkaProperties is the org.springframework.boot.autoconfigure.kafka.KafkaProperties coming from the Spring Boot Kafka autoconfiguration.

@ajax-osadchuk-r
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ajax-osadchuk-r commented Dec 14, 2023 •
edited
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As a workaround, I did this:

Map<String, Object> props = kafkaProperties.buildProducerProperties(null);

//reactor-kafka 1.3.22 casts the given bootstrap servers arraylist to a string and throws a class cast exception
//https://github.com/reactor/reactor-kafka/issues/374
props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, String.join(",", kafkaProperties.getProducer().getBootstrapServers()));

SenderOptions<String, CloudEvent> senderOptions = SenderOptions.create(props);
...

This is an example for the producer side, the same holds for the consumer side.

kafkaProperties is the org.springframework.boot.autoconfigure.kafka.KafkaProperties coming from the Spring Boot Kafka autoconfiguration.

Yes, a have also used such workaround, it works.

This was referenced Dec 20, 2023
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@emmanuelsilva
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Hey all, I also came across this class cast exception when using Spring Boot. I opened the merge request #376 to fix it in the library. Let's see how it goes.

@artembilan artembilan added this to the 1.3.23 milestone Jan 3, 2024
@artembilan artembilan added type/bug A general bug and removed ❓need-triage This issue needs triage, hasn't been looked at by a team member yet labels Jan 3, 2024
artembilan pushed a commit that referenced this issue Jan 10, 2024
@emmanuelsilva
GH-374: Support bootstrap server property as a list
9b09225 
Resolves #374

* support read bootstrap server config when it is defined as list

* update copyright year of the affected classes to 2024
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type/bug A general bug
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Milestone
1.3.23
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@sanderino666 @artembilan @emmanuelsilva @reactorbot @ajax-osadchuk-r