<p>I'm trying to create a kafka cluster deployed on kubernetes. I have the following configuration:</p>

<p>Kafka service:</p>

<pre><code>apiVersion: v1
kind: Service
metadata:
  name: kafka
  labels:
    app: kafka
  namespace: kafka
spec:
  ports:
  - name: kafka-port
    port: 9093
    protocol: TCP
  selector:
    app: kafka
  type: NodePort
</code></pre>

<p>Kafka StatefullSet:</p>

<pre><code>apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: kafka
  namespace: kafka
  labels:
    app: kafka
spec:
  replicas: 1
  serviceName: kafka
  podManagementPolicy: Parallel
  updateStrategy:
    type: RollingUpdate
  selector:
    matchLabels:
      app: kafka
  template:
    metadata:
      labels:
        app: kafka
    spec:
      containers:
      - name: kafka
        imagePullPolicy: Always
        image: wurstmeister/kafka
        ports:
        - containerPort: 9093
        command:
        - sh
        - -c
        - "exec kafka-server-start.sh /opt/kafka/config/server.properties --override broker.id=${HOSTNAME##*-} \
                  --override listeners=PLAINTEXT://:9093 \
                  --override zookeeper.connect=zookeeper:2181 \
                  --override log.dir=/var/lib/kafka \
                  --override auto.create.topics.enable=true \
                  --override auto.leader.rebalance.enable=true \
                  --override background.threads=10 \
                  --override compression.type=producer \
                  --override delete.topic.enable=false \
                  --override leader.imbalance.check.interval.seconds=300 \
                  --override leader.imbalance.per.broker.percentage=10 \
                  --override log.flush.interval.messages=9223372036854775807 \
                  --override log.flush.offset.checkpoint.interval.ms=60000 \
                  --override log.flush.scheduler.interval.ms=9223372036854775807 \
                  --override log.retention.bytes=-1 \
                  --override log.retention.hours=168 \
                  --override log.roll.hours=168 \
                  --override log.roll.jitter.hours=0 \
                  --override log.segment.bytes=1073741824 \
                  --override log.segment.delete.delay.ms=60000 \
                  --override message.max.bytes=1000012 \
                  --override min.insync.replicas=1 \
                  --override num.io.threads=8 \
                  --override num.network.threads=3 \
                  --override num.recovery.threads.per.data.dir=1 \
                  --override num.replica.fetchers=1 \
                  --override offset.metadata.max.bytes=4096 \
                  --override offsets.commit.required.acks=-1 \
                  --override offsets.commit.timeout.ms=5000 \
                  --override offsets.load.buffer.size=5242880 \
                  --override offsets.retention.check.interval.ms=600000 \
                  --override offsets.retention.minutes=1440 \
                  --override offsets.topic.compression.codec=0 \
                  --override offsets.topic.num.partitions=50 \
                  --override offsets.topic.replication.factor=1 \
                  --override offsets.topic.segment.bytes=104857600 \
                  --override queued.max.requests=500 \
                  --override quota.consumer.default=9223372036854775807 \
                  --override quota.producer.default=9223372036854775807 \
                  --override replica.fetch.min.bytes=1 \
                  --override replica.fetch.wait.max.ms=500 \
                  --override replica.high.watermark.checkpoint.interval.ms=5000 \
                  --override replica.lag.time.max.ms=10000 \
                  --override replica.socket.receive.buffer.bytes=65536 \
                  --override replica.socket.timeout.ms=30000 \
                  --override request.timeout.ms=30000 \
                  --override socket.receive.buffer.bytes=102400 \
                  --override socket.request.max.bytes=104857600 \
                  --override socket.send.buffer.bytes=102400 \
                  --override unclean.leader.election.enable=true \
                  --override zookeeper.session.timeout.ms=6000 \
                  --override zookeeper.set.acl=false \
                  --override broker.id.generation.enable=true \
                  --override connections.max.idle.ms=600000 \
                  --override controlled.shutdown.enable=true \
                  --override controlled.shutdown.max.retries=3 \
                  --override controlled.shutdown.retry.backoff.ms=5000 \
                  --override controller.socket.timeout.ms=30000 \
                  --override default.replication.factor=1 \
                  --override fetch.purgatory.purge.interval.requests=1000 \
                  --override group.max.session.timeout.ms=300000 \
                  --override group.min.session.timeout.ms=6000 \
                  --override inter.broker.protocol.version=0.11.0 \
                  --override log.cleaner.backoff.ms=15000 \
                  --override log.cleaner.dedupe.buffer.size=134217728 \
                  --override log.cleaner.delete.retention.ms=86400000 \
                  --override log.cleaner.enable=true \
                  --override log.cleaner.io.buffer.load.factor=0.9 \
                  --override log.cleaner.io.buffer.size=524288 \
                  --override log.cleaner.io.max.bytes.per.second=1.7976931348623157E308 \
                  --override log.cleaner.min.cleanable.ratio=0.5 \
                  --override log.cleaner.min.compaction.lag.ms=0 \
                  --override log.cleaner.threads=1 \
                  --override log.cleanup.policy=delete \
                  --override log.index.interval.bytes=4096 \
                  --override log.index.size.max.bytes=10485760 \
                  --override log.message.timestamp.difference.max.ms=9223372036854775807 \
                  --override log.message.timestamp.type=CreateTime \
                  --override log.preallocate=false \
                  --override log.retention.check.interval.ms=300000 \
                  --override max.connections.per.ip=2147483647 \
                  --override num.partitions=1 \
                  --override producer.purgatory.purge.interval.requests=1000 \
                  --override replica.fetch.backoff.ms=1000 \
                  --override replica.fetch.max.bytes=1048576 \
                  --override replica.fetch.response.max.bytes=10485760 \
                  --override reserved.broker.max.id=1000 "
        volumeMounts:
        - name: datadir
          mountPath: /var/lib/kafka
        readinessProbe:
          exec:
            command:
            - sh
            - -c
            - "/opt/kafka/bin/kafka-broker-api-versions.sh --bootstrap-server=localhost:9093"
  volumeClaimTemplates:
  - metadata:
      name: datadir
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 10Gi
</code></pre>

<p>Zookeeper service:</p>

<pre><code>apiVersion: v1
kind: Service
metadata:
  name: zookeeper
  namespace: kafka
  labels:
    name: zookeeper
spec:
  ports:
  - name: client
    port: 2181
    protocol: TCP
  - name: follower
    port: 2888
    protocol: TCP
  - name: leader
    port: 3888
    protocol: TCP
  selector:
    name: zookeeper
</code></pre>

<p>Zookeeper Deployment:</p>

<pre><code>apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: zookeeper
  namespace: kafka
spec:
  replicas: 1
  template:
    metadata:
      labels:
        name: zookeeper
    spec:
      containers:
      - env:
        - name: ZOOKEEPER_ID
          value: "1"
        - name: ZOOKEEPER_SERVER_1
          value: zookeeper
        name: zookeeper
        image: digitalwonderland/zookeeper
        ports:
        - containerPort: 2181
</code></pre>

<p>With this configuration all works well. But I want to add more replicas of kafka. If i try to add another replica, I receive this error:</p>

<pre><code>Error connecting to node kafka-1.kafka.kafka.svc.cluster.local:9093 (id: 1 rack: null) (org.apache.kafka.clients.NetworkClient)
java.io.IOException: Can't resolve address: kafka-1.kafka.kafka.svc.cluster.local:9093
</code></pre>

<p>I can’t figure out where "kafka-1.kafka.kafka.svc.cluster.local" is set and if I can come from that. I can see a solution would be to create a service for every pod but with this approach the cluster doesn’t scale easily.</p>

<p>Can I configure my kafka stateful to discover each other without any other service?</p>

<p>EDIT:</p>

<p>The configuration with one replica works only from cluster, if I'm trying to access broker from outside I receive the exception:</p>

<pre><code>Can't resolve address: kafka-0.kafka.kafka.svc.cluster.local:9093
</code></pre>

<p>Thanks</p>

Dorin
<p>You need to set the <code>.metadata.name</code> in the service definition and the <code>.spec.serviceName</code> in the deploy definition to the same name, and the service should be headless service, with <code>'clusterIP: None'</code> in your setup, then you can resolve <code>kafka-0.kafka.kafka.svc.cluster.local</code> to the pod ip.</p>
