Kafka Streams not reading input topic

Question

I have created sample Kafka Streams application from the tutorial:

    public static void main(String[] args) throws Exception {
    Logger log = Logger.getLogger("Name");

    Properties props = new Properties();
    props.put(StreamsConfig.APPLICATION_ID_CONFIG, "streams-wordprint");
    props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "192.168.99.100:9092");
    props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass());
    props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass());

    final KStreamBuilder builder = new KStreamBuilder();
    builder.stream("onecon_postgres").print();

    final KafkaStreams streams = new KafkaStreams(builder, props);
    final CountDownLatch latch = new CountDownLatch(1);

    // attach shutdown handler to catch control-c
    Runtime.getRuntime().addShutdownHook(new Thread("streams-shutdown-hook") {
        @Override
        public void run() {
            streams.close();
            latch.countDown();
        }
    });

    try {
        streams.start();
        log.info("After Start");
        latch.await();
    } catch (Throwable e) {
        System.exit(1);
    }
    System.exit(0);
    }

Unfortunately this application does not read input stream. I have a JDBC source connector from PostgreSQL and it's working fine streaming data from one database (I can see on Kafka Connect UI data within this topic).

The problem I have is even though I have changed IP in BOOTSTRAP_SERVERS_CONFIG in Properties IP is localhost I don't know why.

[main] INFO org.apache.kafka.streams.StreamsConfig - StreamsConfig values: 
    application.id = streams-linesplit
    application.server = 
    **bootstrap.servers = [localhost:9092]**
    buffered.records.per.partition = 1000
    cache.max.bytes.buffering = 10485760
    client.id = 
    commit.interval.ms = 30000
    connections.max.idle.ms = 540000
    default.key.serde = class org.apache.kafka.common.serialization.Serdes$StringSerde
    default.timestamp.extractor = class org.apache.kafka.streams.processor.FailOnInvalidTimestamp
    default.value.serde = class org.apache.kafka.common.serialization.Serdes$StringSerde
    key.serde = null
    metadata.max.age.ms = 300000
    metric.reporters = []
    metrics.num.samples = 2
    metrics.recording.level = INFO
    metrics.sample.window.ms = 30000
    num.standby.replicas = 0
    num.stream.threads = 1
    partition.grouper = class org.apache.kafka.streams.processor.DefaultPartitionGrouper
    poll.ms = 100
    processing.guarantee = at_least_once
    receive.buffer.bytes = 32768
    reconnect.backoff.max.ms = 1000
    reconnect.backoff.ms = 50
    replication.factor = 1
    request.timeout.ms = 40000
    retry.backoff.ms = 100
    rocksdb.config.setter = null
    security.protocol = PLAINTEXT
    send.buffer.bytes = 131072
    state.cleanup.delay.ms = 600000
    state.dir = /tmp/kafka-streams
    timestamp.extractor = null
    value.serde = null
    windowstore.changelog.additional.retention.ms = 86400000
    zookeeper.connect = 

To overcome this I have used netsh to forward traffic but I cannot see this application to consume my stream.

netsh interface portproxy add v4tov4 listenport=9092 listenaddress=127.0.0.1 connectport=9092 connectaddress=192.168.99.100

Answer 1

Unfortunately this application does not read input stream.

You seem to have a networking problem between your Kafka Streams application and your Kafka broker. It is rather unlikely that "Kafka Streams does not work".

Also, it's hard to help you without you providing more information:

• What Kafka version does your Kafka broker use?
• What Kafka (Streams) version does your application use?
• Which operating system?
• What is the networking setup?
  • IP address of the machine that runs your application.
  • On which IP + port is your Kafka broker (or brokers) listening for new connections? Is it 192.168.99.100:9092 ?
• What do you see in the application's logs? Do you see ERROR or WARN log messages?

The problem I have is even though I have changed IP in BOOTSTRAP_SERVERS_CONFIG in Properties IP is localhost I don't know why.

I don't understand -- why do you think changing the BOOTSTRAP_SERVERS_CONFIG to localhost:9092 will fix your original problem? I understood that the Kafka broker actually listens on 192.168.99.100:9092 ?

To overcome this I have used netsh to forward traffic but I cannot see this application to consume my stream.

The port forwarding will most probably not help. Without updating the configuration of your Kafka broker, the broker will by default only communicate on its "real" IP + port. Slightly simplified: the broker, configured to listen on 192.168.99.100:9092 , will not respond to localhost:9092 request that your Kafka Streams application sends, even though you are doing port forwarding from localhost:9092 -> 192.168.99.100:9092 on the machine that runs your Kafka Streams application.

Hope this helps a bit!