I have a Kafka cluster running on Kubernetes along with ZooKeeper on Kubernetes. As outlined in this answer, I have configured the internal broker port as well as the advertised external port for the clients:

listener.security.protocol.map=PLAINTEXT:PLAINTEXT,PLAINTEXT_HOST:PLAINTEXT

inter.broker.listener.name=PLAINTEXT

listeners=PLAINTEXT://:29092,PLAINTEXT_HOST://0.0.0.0:9093

advertised.listeners=PLAINTEXT://:29092,PLAINTEXT_HOST://{EXTERNAL-IP-ADDRESS}:9093

zookeeper.connect=zk-cs.analytics.svc:2181

I expect the inter-broker communication to happen on 29092. External clients should be able to connect on port 9093. I have one external IP for the entire Kubernetes service, which means that this is the only external IP that should be exposed from the Kafka brokers. As far as I understand, the Kubernetes load balancer will route any request to this IP to one of my brokers.

I have validated that my kafka brokers registered correctly to ZooKeeper:

get /brokers/ids/0
{"listener_security_protocol_map":{"PLAINTEXT":"PLAINTEXT","PLAINTEXT_HOST":"PLAINTEXT"},"endpoints":["PLAINTEXT://kafka-0.kafka-hs.analytics.svc.cluster.local:29092","PLAINTEXT_HOST://{EXTERNAL-IP-ADDRESS}"],"jmx_port":-1,"host":"kafka-0.kafka-hs.analytics.svc.cluster.local","timestamp":"1525689391350","port":29092,"version":4}
cZxid = 0x90000029f
ctime = Mon May 07 12:36:31 CEST 2018
mZxid = 0x90000029f
mtime = Mon May 07 12:36:31 CEST 2018
pZxid = 0x90000029f
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x1632acfab520009
dataLength = 344
numChildren = 0

Creating a topic looks good in the logs to me, logs are below.

Primary:

[2018-05-07 10:41:12,760] DEBUG [TopicChangeListener on Controller 0]: Topic change listener fired for path /brokers/topics with children test-topic (kafka.controller.PartitionStateMachine$TopicChangeListener)
[2018-05-07 10:41:12,767] INFO [TopicChangeListener on Controller 0]: New topics: [Set(test-topic)], deleted topics: [Set()], new partition replica assignment [Map([test-topic,0] -> List(0, 1))] (kafka.controller.PartitionStateMachine$TopicChangeListener)
[2018-05-07 10:41:12,768] INFO [Controller 0]: New topic creation callback for [test-topic,0] (kafka.controller.KafkaController)
[2018-05-07 10:41:12,770] INFO [Controller 0]: New partition creation callback for [test-topic,0] (kafka.controller.KafkaController)
[2018-05-07 10:41:12,771] INFO [Partition state machine on Controller 0]: Invoking state change to NewPartition for partitions [test-topic,0] (kafka.controller.PartitionStateMachine)
[2018-05-07 10:41:12,772] TRACE Controller 0 epoch 12 changed partition [test-topic,0] state from NonExistentPartition to NewPartition with assigned replicas 0,1 (state.change.logger)
[2018-05-07 10:41:12,774] INFO [Replica state machine on controller 0]: Invoking state change to NewReplica for replicas [Topic=test-topic,Partition=0,Replica=0],[Topic=test-topic,Partition=0,Replica=1] (kafka.controller.ReplicaStateMachine)
[2018-05-07 10:41:12,778] TRACE Controller 0 epoch 12 changed state of replica 0 for partition [test-topic,0] from NonExistentReplica to NewReplica (state.change.logger)
[2018-05-07 10:41:12,779] TRACE Controller 0 epoch 12 changed state of replica 1 for partition [test-topic,0] from NonExistentReplica to NewReplica (state.change.logger)
[2018-05-07 10:41:12,779] INFO [Partition state machine on Controller 0]: Invoking state change to OnlinePartition for partitions [test-topic,0] (kafka.controller.PartitionStateMachine)
[2018-05-07 10:41:12,780] DEBUG [Partition state machine on Controller 0]: Live assigned replicas for partition [test-topic,0] are: [List(0, 1)] (kafka.controller.PartitionStateMachine)
[2018-05-07 10:41:12,782] DEBUG [Partition state machine on Controller 0]: Initializing leader and isr for partition [test-topic,0] to (Leader:0,ISR:0,1,LeaderEpoch:0,ControllerEpoch:12) (kafka.controller.PartitionStateMachine)
[2018-05-07 10:41:12,805] TRACE Controller 0 epoch 12 changed partition [test-topic,0] from NewPartition to OnlinePartition with leader 0 (state.change.logger)
[2018-05-07 10:41:12,806] TRACE Controller 0 epoch 12 sending become-follower LeaderAndIsr request (Leader:0,ISR:0,1,LeaderEpoch:0,ControllerEpoch:12) to broker 1 for partition [test-topic,0] (state.change.logger)
[2018-05-07 10:41:12,809] TRACE Controller 0 epoch 12 sending become-leader LeaderAndIsr request (Leader:0,ISR:0,1,LeaderEpoch:0,ControllerEpoch:12) to broker 0 for partition [test-topic,0] (state.change.logger)
[2018-05-07 10:41:12,810] TRACE Controller 0 epoch 12 sending UpdateMetadata request (Leader:0,ISR:0,1,LeaderEpoch:0,ControllerEpoch:12) to brokers Set(0, 1, 2, 3, 4) for partition test-topic-0 (state.change.logger)
[2018-05-07 10:41:12,811] INFO [Replica state machine on controller 0]: Invoking state change to OnlineReplica for replicas [Topic=test-topic,Partition=0,Replica=0],[Topic=test-topic,Partition=0,Replica=1] (kafka.controller.ReplicaStateMachine)
[2018-05-07 10:41:12,812] TRACE Controller 0 epoch 12 changed state of replica 0 for partition [test-topic,0] from NewReplica to OnlineReplica (state.change.logger)
[2018-05-07 10:41:12,813] TRACE Controller 0 epoch 12 changed state of replica 1 for partition [test-topic,0] from NewReplica to OnlineReplica (state.change.logger)
[2018-05-07 10:41:12,813] TRACE Broker 0 received LeaderAndIsr request PartitionState(controllerEpoch=12, leader=0, leaderEpoch=0, isr=[0, 1], zkVersion=0, replicas=[0, 1]) correlation id 5 from controller 0 epoch 12 for partition [test-topic,0] (state.change.logger)
[2018-05-07 10:41:12,813] TRACE Broker 0 received LeaderAndIsr request PartitionState(controllerEpoch=12, leader=0, leaderEpoch=0, isr=[0, 1], zkVersion=0, replicas=[0, 1]) correlation id 4 from controller 0 epoch 12 for partition [test-topic,0] (state.change.logger)
[2018-05-07 10:41:12,816] TRACE Broker 0 cached leader info (LeaderAndIsrInfo:(Leader:0,ISR:0,1,LeaderEpoch:0,ControllerEpoch:12),ReplicationFactor:2),AllReplicas:0,1) for partition test-topic-0 in response to UpdateMetadata request sent by controller 0 epoch 12 with correlation id 2 (state.change.logger)
[2018-05-07 10:41:12,817] TRACE Controller 0 epoch 12 received response {error_code=0} for a request sent to broker kafka-2.kafka-hs.analytics.svc.cluster.local:29092 (id: 2 rack: null) (state.change.logger)
[2018-05-07 10:41:12,823] TRACE Controller 0 epoch 12 received response {error_code=0} for a request sent to broker kafka-3.kafka-hs.analytics.svc.cluster.local:29092 (id: 3 rack: null) (state.change.logger)
[2018-05-07 10:41:12,823] TRACE Controller 0 epoch 12 received response {error_code=0} for a request sent to broker kafka-4.kafka-hs.analytics.svc.cluster.local:29092 (id: 4 rack: null) (state.change.logger)
[2018-05-07 10:41:12,827] TRACE Broker 0 handling LeaderAndIsr request correlationId 4 from controller 0 epoch 12 starting the become-leader transition for partition test-topic-0 (state.change.logger)
[2018-05-07 10:41:12,828] INFO [ReplicaFetcherManager on broker 0] Removed fetcher for partitions test-topic-0 (kafka.server.ReplicaFetcherManager)
[2018-05-07 10:41:12,852] INFO Completed load of log test-topic-0 with 1 log segments and log end offset 0 in 17 ms (kafka.log.Log)
[2018-05-07 10:41:12,853] INFO Created log for partition [test-topic,0] in /tmp/kafka-logs with properties {compression.type -> producer, message.format.version -> 0.10.2-IV0, file.delete.delay.ms -> 60000, max.message.bytes -> 1000012, min.compaction.lag.ms -> 0, message.timestamp.type -> CreateTime, min.insync.replicas -> 1, segment.jitter.ms -> 0, preallocate -> false, min.cleanable.dirty.ratio -> 0.5, index.interval.bytes -> 4096, unclean.leader.election.enable -> true, retention.bytes -> -1, delete.retention.ms -> 86400000, cleanup.policy -> [delete], flush.ms -> 9223372036854775807, segment.ms -> 604800000, segment.bytes -> 1073741824, retention.ms -> 604800000, message.timestamp.difference.max.ms -> 9223372036854775807, segment.index.bytes -> 10485760, flush.messages -> 9223372036854775807}. (kafka.log.LogManager)
[2018-05-07 10:41:12,853] INFO Partition [test-topic,0] on broker 0: No checkpointed highwatermark is found for partition test-topic-0 (kafka.cluster.Partition)
[2018-05-07 10:41:12,861] TRACE Broker 0 stopped fetchers as part of become-leader request from controller 0 epoch 12 with correlation id 4 for partition test-topic-0 (state.change.logger)
[2018-05-07 10:41:12,861] TRACE Broker 0 completed LeaderAndIsr request correlationId 4 from controller 0 epoch 12 for the become-leader transition for partition test-topic-0 (state.change.logger)
[2018-05-07 10:41:12,864] WARN Broker 0 ignoring LeaderAndIsr request from controller 0 with correlation id 5 epoch 12 for partition [test-topic,0] since its associated leader epoch 0 is not higher than the current leader epoch 0 (state.change.logger)
[2018-05-07 10:41:12,865] TRACE Controller 0 epoch 12 received response {error_code=0,partitions=[{topic=test-topic,partition=0,error_code=11}]} for a request sent to broker kafka-0.kafka-hs.analytics.svc.cluster.local:29092 (id: 0 rack: null) (state.change.logger)
[2018-05-07 10:41:12,865] TRACE Controller 0 epoch 12 received response {error_code=0,partitions=[{topic=test-topic,partition=0,error_code=0}]} for a request sent to broker kafka-1.kafka-hs.analytics.svc.cluster.local:29092 (id: 1 rack: null) (state.change.logger)
[2018-05-07 10:41:12,867] TRACE Broker 0 cached leader info (LeaderAndIsrInfo:(Leader:0,ISR:0,1,LeaderEpoch:0,ControllerEpoch:12),ReplicationFactor:2),AllReplicas:0,1) for partition test-topic-0 in response to UpdateMetadata request sent by controller 0 epoch 12 with correlation id 6 (state.change.logger)
[2018-05-07 10:41:12,867] TRACE Controller 0 epoch 12 received response {error_code=0} for a request sent to broker kafka-0.kafka-hs.analytics.svc.cluster.local:29092 (id: 0 rack: null) (state.change.logger)
[2018-05-07 10:41:12,867] TRACE Broker 0 cached leader info (LeaderAndIsrInfo:(Leader:0,ISR:0,1,LeaderEpoch:0,ControllerEpoch:12),ReplicationFactor:2),AllReplicas:0,1) for partition test-topic-0 in response to UpdateMetadata request sent by controller 0 epoch 12 with correlation id 5 (state.change.logger)
[2018-05-07 10:41:12,868] TRACE Controller 0 epoch 12 received response {error_code=0} for a request sent to broker kafka-1.kafka-hs.analytics.svc.cluster.local:29092 (id: 1 rack: null) (state.change.logger)
[2018-05-07 10:41:26,213] INFO Partition [test-topic,0] on broker 0: Shrinking ISR for partition [test-topic,0] from 0,1 to 0 (kafka.cluster.Partition)
[2018-05-07 10:41:28,721] DEBUG [IsrChangeNotificationListener on Controller 0]: ISR change notification listener fired (kafka.controller.IsrChangeNotificationListener)
[2018-05-07 10:41:28,735] DEBUG [IsrChangeNotificationListener on Controller 0]: Sending MetadataRequest to Brokers:ArrayBuffer(0, 1, 2, 3, 4) for TopicAndPartitions:Set([test-topic,0], [__consumer_offsets,30], [__consumer_offsets,6]) (kafka.controller.IsrChangeNotificationListener)
[2018-05-07 10:41:28,735] INFO Leader not yet assigned for partition [__consumer_offsets,30]. Skip sending UpdateMetadataRequest. (kafka.controller.ControllerBrokerRequestBatch)
[2018-05-07 10:41:28,735] INFO Leader not yet assigned for partition [__consumer_offsets,6]. Skip sending UpdateMetadataRequest. (kafka.controller.ControllerBrokerRequestBatch)
[2018-05-07 10:41:28,735] TRACE Controller 0 epoch 12 sending UpdateMetadata request (Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:12) to brokers Set(0, 1, 2, 3, 4) for partition test-topic-0 (state.change.logger)
[2018-05-07 10:41:28,739] TRACE Broker 0 cached leader info (LeaderAndIsrInfo:(Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:12),ReplicationFactor:2),AllReplicas:0,1) for partition test-topic-0 in response to UpdateMetadata request sent by controller 0 epoch 12 with correlation id 6 (state.change.logger)
[2018-05-07 10:41:28,739] TRACE Broker 0 cached leader info (LeaderAndIsrInfo:(Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:12),ReplicationFactor:2),AllReplicas:0,1) for partition test-topic-0 in response to UpdateMetadata request sent by controller 0 epoch 12 with correlation id 3 (state.change.logger)
[2018-05-07 10:41:28,739] TRACE Controller 0 epoch 12 received response {error_code=0} for a request sent to broker kafka-1.kafka-hs.analytics.svc.cluster.local:29092 (id: 1 rack: null) (state.change.logger)
[2018-05-07 10:41:28,740] TRACE Broker 0 cached leader info (LeaderAndIsrInfo:(Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:12),ReplicationFactor:2),AllReplicas:0,1) for partition test-topic-0 in response to UpdateMetadata request sent by controller 0 epoch 12 with correlation id 7 (state.change.logger)
[2018-05-07 10:41:28,740] TRACE Controller 0 epoch 12 received response {error_code=0} for a request sent to broker kafka-2.kafka-hs.analytics.svc.cluster.local:29092 (id: 2 rack: null) (state.change.logger)
[2018-05-07 10:41:28,740] TRACE Controller 0 epoch 12 received response {error_code=0} for a request sent to broker kafka-3.kafka-hs.analytics.svc.cluster.local:29092 (id: 3 rack: null) (state.change.logger)
[2018-05-07 10:41:28,740] TRACE Controller 0 epoch 12 received response {error_code=0} for a request sent to broker kafka-0.kafka-hs.analytics.svc.cluster.local:29092 (id: 0 rack: null) (state.change.logger)
[2018-05-07 10:41:28,741] TRACE Controller 0 epoch 12 received response {error_code=0} for a request sent to broker kafka-4.kafka-hs.analytics.svc.cluster.local:29092 (id: 4 rack: null) (state.change.logger)
[2018-05-07 10:41:28,746] DEBUG [IsrChangeNotificationListener on Controller 0]: ISR change notification listener fired (kafka.controller.IsrChangeNotificationListener)
[2018-05-07 10:41:36,297] TRACE [Controller 0]: checking need to trigger partition rebalance (kafka.controller.KafkaController)
[2018-05-07 10:41:36,298] DEBUG [Controller 0]: preferred replicas by broker Map(0 -> Map([test-topic,0] -> List(0, 1))) (kafka.controller.KafkaController)
[2018-05-07 10:41:36,302] DEBUG [Controller 0]: topics not in preferred replica Map() (kafka.controller.KafkaController)
[2018-05-07 10:41:36,303] TRACE [Controller 0]: leader imbalance ratio for broker 0 is 0.000000 (kafka.controller.KafkaController)

Replica #1:

[2018-05-07 10:41:12,822] TRACE Broker 1 cached leader info (LeaderAndIsrInfo:(Leader:0,ISR:0,1,LeaderEpoch:0,ControllerEpoch:12),ReplicationFactor:2),AllReplicas:0,1) for partition test-topic-0 in response to UpdateMetadata request sent by controller 0 epoch 12 with correlation id 3 (state.change.logger)
[2018-05-07 10:41:28,739] TRACE Broker 1 cached leader info (LeaderAndIsrInfo:(Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:12),ReplicationFactor:2),AllReplicas:0,1) for partition test-topic-0 in response to UpdateMetadata request sent by controller 0 epoch 12 with correlation id 4 (state.change.logger)

Replica #2:

[2018-05-07 10:41:12,823] TRACE Broker 2 cached leader info (LeaderAndIsrInfo:(Leader:0,ISR:0,1,LeaderEpoch:0,ControllerEpoch:12),ReplicationFactor:2),AllReplicas:0,1) for partition test-topic-0 in response to UpdateMetadata request sent by controller 0 epoch 12 with correlation id 1 (state.change.logger)
[2018-05-07 10:41:28,740] TRACE Broker 2 cached leader info (LeaderAndIsrInfo:(Leader:0,ISR:0,LeaderEpoch:0,ControllerEpoch:12),ReplicationFactor:2),AllReplicas:0,1) for partition test-topic-0 in response to UpdateMetadata request sent by controller 0 epoch 12 with correlation id 2 (state.change.logger)

However, whenever I connect with the console producer to the cluster, I get the following error:

 .\kafka-console-producer.bat --broker-list {EXTERNAL-IP-ADDRESS}:9093 --topic test-topic --property parse.key=true --property key.separator=:
>testKey:23487239847237894asduhzdfhzusfhhsdf
[2018-05-07 12:42:58,395] WARN [Producer clientId=console-producer] Error while fetching metadata with correlation id 2 : {test-topic=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2018-05-07 12:42:58,512] WARN [Producer clientId=console-producer] Error while fetching metadata with correlation id 3 : {test-topic=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2018-05-07 12:42:58,641] WARN [Producer clientId=console-producer] Error while fetching metadata with correlation id 4 : {test-topic=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2018-05-07 12:42:58,765] WARN [Producer clientId=console-producer] Error while fetching metadata with correlation id 5 : {test-topic=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2018-05-07 12:42:58,886] WARN [Producer clientId=console-producer] Error while fetching metadata with correlation id 6 : {test-topic=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)

Is it a problem that a Kubernetes Service usually exposes one external IP address and all of my Kafka brokers are advertising this IP? Are there solutions to this?