Kubernetes部署Kafka集群

主要参考了https://stackoverflow.com/questions/44651219/kafka-deployment-on-minikube和https://github.com/ramhiser/kafka-kubernetes两个项目，但是这两个项目都是单节点的Kafka，我这里尝试将单节点Kafka扩展为多节点的Kafka集群。

一、单节点Kafka

要搭建Kafka集群，还是要从单节点开始。

1.创建Zookeeper服务zookeeper-svc.yaml和zookeeper-deployment.yaml，用kubectl create -f创建：

apiVersion: v1
kind: Service
metadata:
  labels:
    app: zookeeper-service
  name: zookeeper-service
spec:
  ports:
  - name: zookeeper-port
    port: 2181
    targetPort: 2181
  selector:
    app: zookeeper

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  labels:
    app: zookeeper
  name: zookeeper
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: zookeeper
    spec:
      containers:
      - image: wurstmeister/zookeeper
        imagePullPolicy: IfNotPresent
        name: zookeeper
        ports:
        - containerPort: 2181

2.等pod跑起来，service的endpoint配置成功后，就可以继续创建kafka的kafka-svc.yaml和kafka-deployment.yaml了：

apiVersion: v1
kind: Service
metadata:
  name: kafka-service
  labels:
    app: kafka
spec:
  type: NodePort
  ports:
  - port: 9092
    name: kafka-port
    targetPort: 9092
    nodePort: 30092
    protocol: TCP
  selector:
    app: kafka

kind: Deployment
apiVersion: extensions/v1beta1
metadata:
  name: kafka-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      name: kafka
  template:
    metadata:
      labels:
        name: kafka
        app: kafka
    spec:
      containers:
      - name: kafka
        image: wurstmeister/kafka
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 9092
        env:
        - name: KAFKA_ADVERTISED_PORT
          value: "9092"
        - name: KAFKA_ADVERTISED_HOST_NAME
          value: "[kafka的service的clusterIP]"
        - name: KAFKA_ZOOKEEPER_CONNECT
          value: [zookeeper的service的clusterIP]:2181
        - name: KAFKA_BROKER_ID
          value: "1"

clusterIP通过kubectl get svc进行查看。KAFKA_ZOOKEEPER_CONNECT的值也可以改为zookeeper-service:2181。

3.创建后，需要对服务进行测试。参考了https://blog.csdn.net/boling_cavalry/article/details/78309050的方法。

在此之前，针对虚拟化的Kafka，需要先执行下面的命令以进入容器：

kubectl exec -it [Kafka的pod名称] /bin/bash

进入容器后，Kafka的命令存储在opt/kafka/bin目录下，用cd命令进入：

cd opt/kafka/bin

后面的操作就跟上面的博客中写的类似了。针对单节点Kafka，需要将同一个节点作为生产者和消费者。执行命令如下：

kafka-console-producer.sh --broker-list [kafka的service的clusterIP]:9092 --topic test

运行正常的话，下方会出现>标记以提示输入消息。这样这个终端就成为了生产者。

另外打开一个linux终端，执行相同的命令进入容器。这次将这个终端作为消费者。注意，上面的博客中写的创建消费者的方法在新版的Kafka中已经改变，需要执行下面的命令：

kafka-console-consumer.sh --bootstrap-server [kafka的service的clusterIP]:9092 --topic test --from-beginning

之后，在生产者输入信息，查看消费者是否能够接收到。如果接收到，说明运行成功。

最后，还可以执行下面的命令以测试列出所有的消息主题：

kafka-topics.sh --list --zookeeper [zookeeper的service的clusterIP]:2181

注意，有时需要用Kafka的端口，有时需要用Zookeeper的端口，应注意区分。

二、多节点Kafka集群

单节点服务运行成功后，就可以尝试增加Kafka的节点以建立集群。我的Kubernetes集群包含3个节点，所以我搭建的Kafka集群也包含3个节点，分别运行在三台机器上。

我这里采用了3个Deployment来运行Kafka和Zookeeper，其实更优雅的方式是使用StatefulSet。Kubernetes的官方文档上有使用StatefulSet搭建Zookeeper集群的范例。

但是使用StatefulSet搭建Zookeeper和Kafka时，Zookeeper的myid和Kafka的brokerID就不能预先设置了，因此需要在镜像构建过程中加入相关的操作，而Docker Hub中的绝大多数镜像都不包含这一逻辑。而Deployment虽然不够优雅，但是可以对各节点预先配置，运行起来相对简单，可以说各有所长。

1.搭建Zookeeper集群

创建zookeeper的yaml文件zookeeper-svc2.yaml和zookeeper-deployment2.yaml如下：

apiVersion: v1
kind: Service
metadata:
  name: zoo1
  labels:
    app: zookeeper-1
spec:
  ports:
  - name: client
    port: 2181
    protocol: TCP
  - name: follower
    port: 2888
    protocol: TCP
  - name: leader
    port: 3888
    protocol: TCP
  selector:
    app: zookeeper-1
---
apiVersion: v1
kind: Service
metadata:
  name: zoo2
  labels:
    app: zookeeper-2
spec:
  ports:
  - name: client
    port: 2181
    protocol: TCP
  - name: follower
    port: 2888
    protocol: TCP
  - name: leader
    port: 3888
    protocol: TCP
  selector:
    app: zookeeper-2
---
apiVersion: v1
kind: Service
metadata:
  name: zoo3
  labels:
    app: zookeeper-3
spec:
  ports:
  - name: client
    port: 2181
    protocol: TCP
  - name: follower
    port: 2888
    protocol: TCP
  - name: leader
    port: 3888
    protocol: TCP
  selector:
    app: zookeeper-3

kind: Deployment
apiVersion: extensions/v1beta1
metadata:
  name: zookeeper-deployment-1
spec:
  replicas: 1
  selector:
    matchLabels:
      app: zookeeper-1
      name: zookeeper-1
  template:
    metadata:
      labels:
        app: zookeeper-1
        name: zookeeper-1
    spec:
      containers:
      - name: zoo1
        image: digitalwonderland/zookeeper
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 2181
        env:
        - name: ZOOKEEPER_ID
          value: "1"
        - name: ZOOKEEPER_SERVER_1
          value: zoo1
        - name: ZOOKEEPER_SERVER_2
          value: zoo2
        - name: ZOOKEEPER_SERVER_3
          value: zoo3
---
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
  name: zookeeper-deployment-2
spec:
  replicas: 1
  selector:
    matchLabels:
      app: zookeeper-2
      name: zookeeper-2
  template:
    metadata:
      labels:
        app: zookeeper-2
        name: zookeeper-2
    spec:
      containers:
      - name: zoo2
        image: digitalwonderland/zookeeper
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 2181
        env:
        - name: ZOOKEEPER_ID
          value: "2"
        - name: ZOOKEEPER_SERVER_1
          value: zoo1
        - name: ZOOKEEPER_SERVER_2
          value: zoo2
        - name: ZOOKEEPER_SERVER_3
          value: zoo3
---
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
  name: zookeeper-deployment-3
spec:
  replicas: 1
  selector:
    matchLabels:
      app: zookeeper-3
      name: zookeeper-3
  template:
    metadata:
      labels:
        app: zookeeper-3
        name: zookeeper-3
    spec:
      containers:
      - name: zoo3
        image: digitalwonderland/zookeeper
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 2181
        env:
        - name: ZOOKEEPER_ID
          value: "3"
        - name: ZOOKEEPER_SERVER_1
          value: zoo1
        - name: ZOOKEEPER_SERVER_2
          value: zoo2
        - name: ZOOKEEPER_SERVER_3
          value: zoo3

这里创建了3个deployment和3个service，一一对应。这样，三个实例都可以对外提供服务。

创建完成后，需要用kubectl logs查看一下三个Zookeeper的pod的日志，确保没有错误发生，并且在3个节点的日志中，有类似下面的语句，则表明Zookeeper集群已顺利搭建成功。

2016-10-06 14:04:05,904 [myid:2] - INFO [QuorumPeer[myid=2]/0:0:0:0:0:0:0:0:2181:Leader@358] - LEADING - 
LEADER ELECTION TOOK - 2613

2.搭建Kafka集群

同样创建3个deployment和3个service，编写kafka-svc2.yaml和kafka-deployment2.yaml如下：

apiVersion: v1
kind: Service
metadata:
  name: kafka-service-1
  labels:
    app: kafka-service-1
spec:
  type: NodePort
  ports:
  - port: 9092
    name: kafka-service-1
    targetPort: 9092
    nodePort: 30901
    protocol: TCP
  selector:
    app: kafka-service-1
---
apiVersion: v1
kind: Service
metadata:
  name: kafka-service-2
  labels:
    app: kafka-service-2
spec:
  type: NodePort
  ports:
  - port: 9092
    name: kafka-service-2
    targetPort: 9092
    nodePort: 30902
    protocol: TCP
  selector:
    app: kafka-service-2
---
apiVersion: v1
kind: Service
metadata:
  name: kafka-service-3
  labels:
    app: kafka-service-3
spec:
  type: NodePort
  ports:
  - port: 9092
    name: kafka-service-3
    targetPort: 9092
    nodePort: 30903
    protocol: TCP
  selector:
    app: kafka-service-3

kind: Deployment
apiVersion: extensions/v1beta1
metadata:
  name: kafka-deployment-1
spec:
  replicas: 1
  selector:
    matchLabels:
      name: kafka-service-1
  template:
    metadata:
      labels:
        name: kafka-service-1
        app: kafka-service-1
    spec:
      containers:
      - name: kafka-1
        image: wurstmeister/kafka
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 9092
        env:
        - name: KAFKA_ADVERTISED_PORT
          value: "9092"
        - name: KAFKA_ADVERTISED_HOST_NAME
          value: [kafka-service1的clusterIP]
        - name: KAFKA_ZOOKEEPER_CONNECT
          value: zoo1:2181,zoo2:2181,zoo3:2181
        - name: KAFKA_BROKER_ID
          value: "1"
        - name: KAFKA_CREATE_TOPICS
          value: mytopic:2:1
---
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
  name: kafka-deployment-2
spec:
  replicas: 1
  selector:
  selector:
    matchLabels:
      name: kafka-service-2
  template:
    metadata:
      labels:
        name: kafka-service-2
        app: kafka-service-2
    spec:
      containers:
      - name: kafka-2
        image: wurstmeister/kafka
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 9092
        env:
        - name: KAFKA_ADVERTISED_PORT
          value: "9092"
        - name: KAFKA_ADVERTISED_HOST_NAME
          value: [kafka-service2的clusterIP]
        - name: KAFKA_ZOOKEEPER_CONNECT
          value: zoo1:2181,zoo2:2181,zoo3:2181
        - name: KAFKA_BROKER_ID
          value: "2"
---
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
  name: kafka-deployment-3
spec:
  replicas: 1
  selector:
  selector:
    matchLabels:
      name: kafka-service-3
  template:
    metadata:
      labels:
        name: kafka-service-3
        app: kafka-service-3
    spec:
      containers:
      - name: kafka-3
        image: wurstmeister/kafka
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 9092
        env:
        - name: KAFKA_ADVERTISED_PORT
          value: "9092"
        - name: KAFKA_ADVERTISED_HOST_NAME
          value: [kafka-service3的clusterIP]
        - name: KAFKA_ZOOKEEPER_CONNECT
          value: zoo1:2181,zoo2:2181,zoo3:2181
        - name: KAFKA_BROKER_ID
          value: "3"

在deployment1中执行了创建一个新topic的操作。

3.测试

测试方法基本同单集群的情况，这里就不赘述了。不同的是，这次可以将不同的节点作为生产者和消费者。

至此，Kubernetes的Kafka集群搭建就大功告成了！