Spring Kafka. Not started EmbeddedKafkaBroker

Question

I am coding Kafka Broker and Consumer to catch messages from the application. When trying to get messages from Consumer, an error occurs

java.net.ConnectException: Connection refused: no further information
    at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
    at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
    at org.apache.kafka.common.network.PlaintextTransportLayer.finishConnect(PlaintextTransportLayer.java:50)
    at org.apache.kafka.common.network.KafkaChannel.finishConnect(KafkaChannel.java:216)
    at org.apache.kafka.common.network.Selector.pollSelectionKeys(Selector.java:531)
    at org.apache.kafka.common.network.Selector.poll(Selector.java:483)
    at org.apache.kafka.clients.NetworkClient.poll(NetworkClient.java:540)
    at org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:262)
    at org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:233)
    at org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:212)
    at org.apache.kafka.clients.consumer.internals.AbstractCoordinator.ensureCoordinatorReady(AbstractCoordinator.java:230)
    at org.apache.kafka.clients.consumer.internals.ConsumerCoordinator.poll(ConsumerCoordinator.java:444)
    at org.apache.kafka.clients.consumer.KafkaConsumer.updateAssignmentMetadataIfNeeded(KafkaConsumer.java:1267)
    at org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:1231)
    at org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:1211)
    at org.springframework.kafka.test.utils.KafkaTestUtils.getRecords(KafkaTestUtils.java:303)
    at org.springframework.kafka.test.utils.KafkaTestUtils.getRecords(KafkaTestUtils.java:280)

On the application side (Producer), there is also a connection error

2020-03-25 12:29:33.689  WARN 25786 --- [ad | producer-1] org.apache.kafka.clients.NetworkClient   : [Producer clientId=producer-1, transactionalId=tx0] Connection to node -1 (<here broker hostname>:9092) could not be established. Broker may not be available.

My project has the following dependencies:

compile "org.springframework.kafka:spring-kafka-test:2.4.4.RELEASE"
compile "org.springframework.kafka:spring-kafka:2.4.4.RELEASE"

Code of My Kafka Broker

public class KafkaServer {

    private static final String BROKERPORT = "9092";
    private static final String BROKERHOST = "localhost";
    public static final String TOPIC1 = "fss-fsstransdata";
    public static final String TOPIC2 = "fss-fsstransscores";
    public static final String TOPIC3 = "fss-fsstranstimings";
    public static final String TOPIC4 = "fss-fssdevicedata";
    @Getter
    private Consumer<String, String> consumer;

    private EmbeddedKafkaBroker embeddedKafkaBroker;

    public void run() {

        String[] topics = {TOPIC1, TOPIC2, TOPIC3, TOPIC4};

        this.embeddedKafkaBroker = new EmbeddedKafkaBroker(
                1,
                false,
                1,
                topics
        ).kafkaPorts(BROKERPORT);

        Map<String, Object> configs = new HashMap<>(KafkaTestUtils.consumerProps("consumer", "false", this.embeddedKafkaBroker));
        this.consumer = new DefaultKafkaConsumerFactory<>(configs, new StringDeserializer(), new StringDeserializer()).createConsumer();

        this.consumer.subscribe(Arrays.asList(topics));
    } 
}

Please help to deal with the situation. I am not good at kafka architecture and how it can be implemented on Spring.

Answer 1

The EmbeddedKafkaBroker is designed to be used from a Spring application context or by a JUnit4 @Rule or @ClassRule or by a JUnit5 Condition.

To use it outside those environments, you must call afterPropertiesSet() to initialize it and destroy() to shut it down.

Answer 2

If you are using spring then you need to annotate your bean with @EmbeddedKafka and then use @Autowire on EmbeddedKafkaBroker

Example embeded kafka annotation configuration:

@EmbeddedKafka(
    partitions = 1, 
    controlledShutdown = false,
    brokerProperties = {// place your proerties here
})

What I would do is to create a spring bean KafkaServerConfig and place all my logic for configuration and bean construction inside.

PS: it should be noted that EmbeddedKafkaBroker is intended for unit tests.