UnknownHostException: kafka-zookeeper-client: Name or service not known

[mausch]

Hi, I installed https://github.com/strimzi/strimzi-kafka-operator/blob/0.38.0/examples/kafka/kafka-persistent-single.yaml
Zookeeper runs just fine.
Broker crashloops with "UnknownHostException: kafka-zookeeper-client: Name or service not known"
The broker config (displayed when the pod starts up) has zookeeper.connect=kafka-zookeeper-client:2181. However the zookeeper pod's name is kafka-zookeeper-0 . Any ideas?

[ppatierno]

The broker configuration is right, because brokers are using a Kubernetes Service named like <kafka_cluster_name>-zookeeper-client to connect to ZooKeeper nodes as clients. I would check if you have any DNS issue in your environment because the ZK client is not able to resolve the host.

[mausch]

Thanks! Right, yes, just noticed that. Service kafka-zookeeper-client is bound fine to pod kafka-zookeeper-0. I can resolve it just fine from other pods too... 🤷‍♂️

[scholzj]

I guess you would need to look into your DNS and Kubernetes cluster. They are responsible for DNS resolution. I have no idea what environment do you use, but this can be also sometimes faulty juts on one worker node and when you start a pod on another node it works fine. You can also try to delete the pod and have it recreated in case it was just some temporary glitch.

[mausch]

Fixed, it was a faulty security group in one nodegroup which prevented talking to CoreDNS pods in a different nodegroup.