Events Kafka cluster configuration overview

This page summarizes the configuration of the Kafka cluster for Roundtable’s Events service, which is deployed through the Strimzi Cluster Operator. Refer to the kafka.yaml resource as the most definition reference for the Kafka cluster deployment; this page adds additional context.

Pod scheduling

Both the Kafka Brokers and Zookeeper pods have dedicated access to the events node pool. Since the events pool currently only have three nodes, Kafka Brokers and Zookeeper pods are co-located:

  • Using a toleration, both the Kafka Brokers and Zookeeper pods tolerate the dedicated: events taint.
  • Using a node affinity, Kafka Brokers and Zookeeper pods are required to be scheduled on the events pool’s nodes.
  • Use a pod anti-affinity, Kafka Brokers will not be scheduled on the same node as other brokers. Likewise, Zookeeper pods will not be scheduled on the node as other Zookeeper pods.

Thus Brokers and Zookeepers are typically seen in a pair on each node of the events node pool. The pod resource requests and limits are based on the assumption that the Kafka Broker and Zookeeper instance are the only tenants on each node.


Both the Kafka Brokers and Zookeeper pods use persistent volumes with the faster StorageClass (SSD-based, defined by the roundtable application). This storage class supports volume expansion: increase the storage capacity by increasing the sizes in kafka.yaml.

Listeners and authentication

The cluster has an internal listener on port 9093, which supports mutual TLS authentication between the client and brokers. See Creating a Kafka user with mutual TLS authentication for details on how create a KafkaUser resource and use the corresponding Kubernetes Secret resource with client TLS certificates.


Authorization is enabled for this cluster. This means that that Kafka clients need a corresponding KafkaUser resource with corresponding access permissions. See the Strimzi Authorization documentation for more information.

Kafka configuration

The Kafka brokers are configured to disallow automatic topic creation (auto.create.topics.enable: "false"). Doing so prevents clients from accidentally creating new topics just by subscribing to a typo’d topic name.

See the spec.kafka.config field of kafka.yaml for the complete list of configuration overrides.