CODEWITHSUNDEEP
kubernetesapache-kafka
zulv
zulv

Reputation: 587

How to expose kafka for external access after build kafka cluster on kubernetes?

I build kafka cluster on kubernetes following this guilde https://github.com/kubernetes/contrib/tree/master/statefulsets/kafka, it works well for sending/producing message from kubernetes. when I try to expose the kafka cluster using NodePort as follows, kafka clients try to consumer/produce the message from the address 10.xx.xx.xx:30092

will be failed:

apiVersion: v1
kind: Service
metadata:
  name: kafka-nodeport
  labels:
    app: kafka
spec:
  type: NodePort
  ports:
  - port: 9092
    nodePort: 30092
    name: server
  selector:
    app: kafka

Why that happened and How to expose the kafka service?

Upvotes: 0

Views: 8273

Answers (3)

Doan Thai
Doan Thai

Reputation: 685

Just add ClusterIP and Node IP(External IP) to ADVERTISED_LISTENERS. This is example file yaml deploy kafka in k8s, I use minikube on local with IP is 192.168.49.2

apiVersion: v1
kind: List
items:
  - apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: sp-kafka-1
      namespace: sp-share-services
    spec:
      selector:
        matchLabels:
          service: sp-kafka-1
      template:
        metadata:
          labels:
            service: sp-kafka-1
        spec:
          containers:
            - name: zookeeper
              image: confluentinc/cp-zookeeper
              ports:
                - containerPort: 2181
              env:
                - name: ZOOKEEPER_CLIENT_PORT
                  value: "2181"
                - name: ZOOKEEPER_TICK_TIME
                  value: "2000"
            - name: sp-kafka-1
              image: confluentinc/cp-kafka
              ports:
                - containerPort: 9092
                  name: default
                - containerPort: 29092
                  name: service
              env:
                - name: POD_IP
                  valueFrom:
                    fieldRef:
                      fieldPath: status.podIP
                - name: KAFKA_BROKER_ID
                  value: "1"
                - name: KAFKA_ZOOKEEPER_CONNECT
                  value: localhost:2181
                - name: KAFKA_ADVERTISED_LISTENERS
                  value: PLAINTEXT://$(POD_IP):9092,DOCKER://$(SP_KAFKA_1_SERVICE_HOST):29092,EXTERNAL://192.168.49.2:31010
                - name: KAFKA_LISTENER_SECURITY_PROTOCOL_MAP
                  value: "PLAINTEXT:PLAINTEXT,EXTERNAL:PLAINTEXT,DOCKER:PLAINTEXT"
                - name: KAFKA_INTER_BROKER_LISTENER_NAME
                  value: PLAINTEXT
                - name: KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR
                  value: "1"
                - name: KAFKA_ADVERTISED_HOST_NAME
                  value: $(POD_IP)

  - apiVersion: v1
    kind: Service
    metadata:
      name: sp-kafka-1
      namespace: sp-share-services
    spec:
      ports:
        - port: 29092
          protocol: TCP
          nodePort: 31011
          name: service

      selector:
        service: sp-kafka-1
      type: LoadBalancer
  • $(POD_IP) is pod id that run internal kafka
  • $(SP_KAFKA_1_SERVICE_HOST) is ClusterIP/ServiceIP that reference to Ip from kind:Service. That name depend your name in Service, example
...
  - apiVersion: v1
    kind: Service
    metadata:
      name: test-kafka # use env TEST_KAFKA_SERVICE_HOST in Deployment
      namespace: sp-share-services
    spec:
...
  • EXTERNAL://192.168.49.2:31010 replace by Node K8s IP

Finally, remember add protocol map PLAINTEXT:PLAINTEXT,EXTERNAL:PLAINTEXT,DOCKER:PLAINTEXT and you can access kafka from host 192.168.49.2:31011

Upvotes: 0

Prafull Ladha
Prafull Ladha

Reputation: 13459

The Kafka Statefulsets require headless service for accessing the brokers. You can change the headless service to Type=NodePort and setting the externalTrafficPolicy=Local. This bypasses the internal load balancing of a Service and traffic destined to a specific node on that node port will only work if a Kafka pod is on that node.

apiVersion: v1
kind: Service
metadata:
  name: kafka-nodeport
  labels:
    app: kafka
spec:
  externalTrafficPolicy: Local
  type: NodePort
  ports:
  - port: 9092
    nodePort: 30092
    name: server
  selector:
    app: kafka

For example, we have two nodes nodeA and nodeB, nodeB is running a kafka pod. nodeA:30092 will not connect but nodeB:30092 will connect to the kafka pod running on nodeB.

Hope this helps.

Upvotes: 1

Saïd Bouras
Saïd Bouras

Reputation: 296

You have to do two things :

1) create either a service resource of type NodePort (like you did) or an Ingress resource.

2) Set the two properties below in Kafka : ADVERTISED_HOST and ADVERTISED_PORT.

Kafka will register to Zookeeper with the ip adress of the node, inside containers network it's the internal ip adress that it used so we have to set thoses properties to tell Kafka to register them instead.

Hopes that's help!

Upvotes: 1

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