Kafka Consumer Coordinator 连接问题，Kafka 0.11.0.3

Question

I can't seem to get my Java Kafka client to work. Symptoms:

"Discovered coordinator" is seen in logs, then less than one second later, "Marking the coordinator... dead" is seen. No more output appears after that.

Debugging the code shows that org.apache.kafka.clients.consumer.KafkaConsumer.poll() never returns. The code is stuck in this do-while loop in the ConsumerNetworkClient class:

public boolean awaitMetadataUpdate(long timeout) {
    long startMs = this.time.milliseconds();
    int version = this.metadata.requestUpdate();

    do {
        this.poll(timeout);
    } while(this.metadata.version() == version && this.time.milliseconds() - startMs < timeout);

    return this.metadata.version() > version;
}

The logs say:

2019-09-25 15:25:45.268 [main]  INFO    org.apache.kafka.clients.consumer.ConsumerConfig    ConsumerConfig values: 
    auto.commit.interval.ms = 5000
    auto.offset.reset = latest
    bootstrap.servers = [localhost:9092]
    check.crcs = true
    client.id = 
    connections.max.idle.ms = 540000
    enable.auto.commit = true
    exclude.internal.topics = true
    fetch.max.bytes = 52428800
    fetch.max.wait.ms = 500
    fetch.min.bytes = 1
    group.id = foo
    heartbeat.interval.ms = 3000
    interceptor.classes = null
    internal.leave.group.on.close = true
    isolation.level = read_uncommitted
    key.deserializer = class org.apache.kafka.common.serialization.StringDeserializer
    max.partition.fetch.bytes = 1048576
    max.poll.interval.ms = 300000
    max.poll.records = 500
    metadata.max.age.ms = 300000
    metric.reporters = []
    metrics.num.samples = 2
    metrics.recording.level = INFO
    metrics.sample.window.ms = 30000
    partition.assignment.strategy = [class org.apache.kafka.clients.consumer.RangeAssignor]
    receive.buffer.bytes = 65536
    reconnect.backoff.max.ms = 1000
    reconnect.backoff.ms = 50
    request.timeout.ms = 305000
    retry.backoff.ms = 100
    sasl.jaas.config = null
    sasl.kerberos.kinit.cmd = /usr/bin/kinit
    sasl.kerberos.min.time.before.relogin = 60000
    sasl.kerberos.service.name = null
    sasl.kerberos.ticket.renew.jitter = 0.05
    sasl.kerberos.ticket.renew.window.factor = 0.8
    sasl.mechanism = GSSAPI
    security.protocol = PLAINTEXT
    send.buffer.bytes = 131072
    session.timeout.ms = 10000
    ssl.cipher.suites = null
    ssl.enabled.protocols = [TLSv1.2, TLSv1.1, TLSv1]
    ssl.endpoint.identification.algorithm = null
    ssl.key.password = null
    ssl.keymanager.algorithm = SunX509
    ssl.keystore.location = null
    ssl.keystore.password = null
    ssl.keystore.type = JKS
    ssl.protocol = TLS
    ssl.provider = null
    ssl.secure.random.implementation = null
    ssl.trustmanager.algorithm = PKIX
    ssl.truststore.location = null
    ssl.truststore.password = null
    ssl.truststore.type = JKS
    value.deserializer = class com.mycompany.KafkaMessageJsonNodeDeserializer

2019-09-25 15:25:45.312 [main]  INFO    org.apache.kafka.common.utils.AppInfoParser -   Kafka version : 0.11.0.3
2019-09-25 15:25:45.312 [main]  INFO    org.apache.kafka.common.utils.AppInfoParser -   Kafka commitId : 26ddb9e3197be39a
2019-09-25 15:25:47.700 [pool-2-thread-1]   INFO    org.apache.kafka.clients.consumer.internals.AbstractCoordinator -   Discovered coordinator ad0c03f60f39:9092 (id: 2147483647 rack: null) for group foo.
2019-09-25 15:25:47.705 [pool-2-thread-1]   INFO    org.apache.kafka.clients.consumer.internals.AbstractCoordinator -   Marking the coordinator ad0c03f60f39:9092 (id: 2147483647 rack: null) dead for group foo

.. if debug was turned on, then logs would also have a message like:

Coordinator discovery failed for group foo, refreshing metadata

More details:

I'm running kafka inside a docker container. When running the console consumer within the docker container, all is well. Messages are received just fine by the console consumer. My app (where the issues occur) is running outside the docker container.

The docker run command includes -p 2181:2181 -p 9001:9001 -p 9092:9092 .

The stack looks like this when the Kafka client gets stuck in the loop:

awaitMetadataUpdate:134, ConsumerNetworkClient (org.apache.kafka.clients.consumer.internals)
ensureCoordinatorReady:226, AbstractCoordinator (org.apache.kafka.clients.consumer.internals)
ensureCoordinatorReady:203, AbstractCoordinator (org.apache.kafka.clients.consumer.internals)
poll:286, ConsumerCoordinator (org.apache.kafka.clients.consumer.internals)
pollOnce:1078, KafkaConsumer (org.apache.kafka.clients.consumer)
poll:1043, KafkaConsumer (org.apache.kafka.clients.consumer)

Answer 1

Looks like, your broker is advertising itself as ad0c03f60f39. And you seem to be running the client from your host machine, which can not resolve ad0c03f60f39 for obvious reason. You need to configure the broker to advertise itself as somthing which is resolvable from the host. Look for "advertised.listeners" in server.properties, you can set something like PLAINTEXT://localhost:9092