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# Kafka on Kubernetes
Transparent Kafka setup that you can grow with.
Good for both experiments and production.
How to use:
* Run a Kubernetes cluster, [minikube](https://github.com/kubernetes/minikube) or real.
* To quickly get a small Kafka cluster running, use the `kubectl apply`s below.
* To start using Kafka for real, fork and have a look at [addon](https://github.com/Yolean/kubernetes-kafka/labels/addon)s.
* Join the discussion here in issues and PRs.
Why?
See for yourself. No single readable readme can properly introduce both Kafka and Kubernets.
Back when we read [Newman](http://samnewman.io/books/building_microservices/) we were beginners with both.
Now we read [Kleppmann](http://dataintensive.net/), [Confluent's blog](https://www.confluent.io/blog/) and [SRE](https://landing.google.com/sre/book.html) and enjoy this "Streaming Platform" lock-in :smile:.
## What you get
[Bootstrap servers](http://kafka.apache.org/documentation/#producerconfigs): `kafka-0.broker.kafka.svc.cluster.local:9092,kafka-1.broker.kafka.svc.cluster.local:9092,kafka-2.broker.kafka.svc.cluster.local:9092`
`
Zookeeper at `zookeeper.kafka.svc.cluster.local:2181`.
## 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](http://kubernetes.io/docs/user-guide/jobs/), 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.
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