#StackBounty: #java #spring-boot #apache-kafka #kubernetes Spring Kafka producers throwing TimeoutExceptions

Bounty: 50


I have a Kafka setup with three brokers in Kubernetes, set up according to the guide at https://github.com/Yolean/kubernetes-kafka. The following error message appears when producing messages from a Java client.

2018-06-06 11:15:44.103 ERROR 1 --- [ad | producer-1] o.s.k.support.LoggingProducerListener    : Exception thrown when sending a message with key='null' and payload='[...redacted...]':
org.apache.kafka.common.errors.TimeoutException: Expiring 1 record(s) for topicname-0: 30001 ms has passed since last append

Detailed setup

The listeners are set up to allow SSL producers/consumers from the outside world:

advertised.host.name = null
advertised.listeners = OUTSIDE://kafka-0.mydomain.com:32400,PLAINTEXT://:9092
advertised.port = null
listeners = OUTSIDE://:9094,PLAINTEXT://:9092
inter.broker.listener.name = PLAINTEXT
host.name =
port.name = 9092

The OUTSIDE listeners are listening on kafka-0.mydomain.com, kafka-1.mydomain.com, etc. The plaintext listeners are listening on any IP, since they are cluster-local to Kubernetes.

The producer settings:

  bootstrap-servers: kafka.mydomain.com:9092
    security.protocol: SSL
    batch-size: 100
    buffer-memory: 1048576 # 1MB
    retries: 1
      key-password: redacted
      keystore-location: file:/var/private/ssl/kafka.client.keystore.jks
      keystore-password: redacted
      truststore-location: file:/var/private/ssl/kafka.client.truststore.jks
      truststore-password: redacted


  • The errors started appearing when the broker was moved moved to SSL.
  • On the server side everything is running as expected, there are no errors in the log and I can connect to the broker manually with a Kafka client tool.
  • The errors appear intermittently: sometimes it sends 30+ messages per second, sometimes it sends nothing at all. It may work like a charm for hours and then just spam timeouts for a little while.

What could it be?

Get this bounty!!!

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