The timer application throws a per-second error when trying to send its message to Kafka:

2017-08-03 10:20:58,805 ERROR kafka-producer-network-thread | producer-2 o.s.k.s.LoggingProducerListener:76 - Exception thrown when sending a message with key='null' and payload='{-1, 2, 11, 99, 111, 110, 116, 101, 110, 116, 84, 121, 112, 101, 0, 0, 0, 12, 34, 116, 101, 120, 116...' to topic metrics: org.apache.kafka.common.errors.TimeoutException: Expiring 2 record(s) for metrics-0 due to 30009 ms has passed since batch creation plus linger time

It seems to me like these would be the records for the metrics topic, but at the same time there are no records in the ticktock.timer topic in Kafka. I'm guessing this partition key being null could be the problem. But I am not so sure why it should use some partitioning setup that is not the default one.

Here's what I deployed:

dataflow:> app register --type sink --name log --uri docker://springcloudstream/log-sink-kafka-10:1.2.0.RELEASE --metadata-uri maven://org.springframework.cloud.stream.app:log-sink-kafka-10:jar:metadata:1.2.0.RELEASE dataflow:> app register --type source --name time --uri docker://springcloudstream/time-source-kafka-10:1.2.0.RELEASE --metadata-uri maven://org.springframework.cloud.stream.app:time-source-kafka-10:jar:metadata:1.2.0.RELEASE dataflow:> stream create --name ticktock --definition "time | log" --deploy

And here's my setup:

spring-cloud-dataflow-server-kubernetes: 1.3.0.BUILD-SNAPSHOT
Spring Cloud Data Flow Core: 1.3.0.BUILD-SNAPSHOT
Spring Cloud Dataflow UI: 1.3.0.BUILD-SNAPSHOT

I'm using Kafka 10 BTW.

What could be the problem?

Many thanks for your support!