Kafka as Kubernetes StatefulSet

Transparent Kafka setup that you can grow with, extendable through addons.

Example of three Kafka brokers depending on five Zookeeper instances.

To get consistent service DNS names kafka-N.broker.kafka(.svc.cluster.local), run everything in a namespace:

kubectl create -f 00namespace.yml

Set up Zookeeper

The Kafka book (Definitive Guide, O'Reilly 2016) recommends that Kafka has its own Zookeeper cluster with at least 5 instances. We use the zookeeper build that comes with the Kafka distribution, and tweak the startup command to support StatefulSet.

kubectl create -f ./zookeeper/

Start Kafka

Assuming you have your PVCs Bound, or enabled automatic provisioning (see above), go ahead and:

kubectl create -f ./

You might want to verify in logs that Kafka found its own DNS name(s) correctly. Look for records like:

kubectl -n kafka logs kafka-0 | grep "Registered broker"
# INFO Registered broker 0 at path /brokers/ids/0 with addresses: PLAINTEXT -> EndPoint(kafka-0.broker.kafka.svc.cluster.local,9092,PLAINTEXT)

Testing manually

There's a Kafka pod that doesn't start the server, so you can invoke the various shell scripts.

kubectl create -f test/99testclient.yml

See ./test/test.sh for some sample commands.

Automated test, while going chaosmonkey on the cluster

This is WIP, but topic creation has been automated. Note that as a Job, it will restart if the command fails, including if the topic exists :(

kubectl create -f test/11topic-create-test1.yml

Pods that keep consuming messages (but they won't exit on cluster failures)

kubectl create -f test/21consumer-test1.yml

Teardown & cleanup

Testing and retesting... delete the namespace. PVs are outside namespaces so delete them too.

kubectl delete namespace kafka
rm -R ./data/ && kubectl -n kafka delete pv datadir-kafka-0 datadir-kafka-1 datadir-kafka-2

Metrics, Prometheus style

Is the metrics system up and running?

kubectl logs -c metrics kafka-0
kubectl exec -c broker kafka-0 -- /bin/sh -c 'apk add --no-cache curl && curl http://localhost:5556/metrics'
kubectl logs -c metrics zoo-0
kubectl exec -c zookeeper zoo-0 -- /bin/sh -c 'apk add --no-cache curl && curl http://localhost:5556/metrics'

Metrics containers can't be used for the curl because they're too short on memory.