Kubernetes StatefulSet with zookeeper

介绍

官方文档https://kubernetes.io/zh/docs/tutorials/stateful-application/zookeeper/

在部署之前，你需要熟悉以下Kubernetes概念

• • Pods
  • Cluster DNS
  • Headless Services
  • PersistentVolumes
  • PersistentVolume Provisioning
  • StatefulSets
  • PodDisruptionBudgets
  • PodAntiAffinity
  • kubectl CLI

根据官方要求，zookeeper部署在Kubernetes集群需要具备如下要求

• • node节点资源至少四个节点的集群，每个节点至少 2 CPUs 和 4 GiB 内存

如果在云平台部署zookeeper集群，需要学习相关云厂商的持久化存储，如何与Kubernetes集群融合

配置过程

---

 整个部署分为以下几个步骤（为了细化官方文档部署过程，以下具体的分段），官方文档给出的example.yaml有缺少遗漏的部分，在下文一一指出，如下

1. 创建StorageClass
2. 创建PersistentVolumeClaim
3. 创建Headless Service
4. 创建PodDisruptionBudget
5. 创建StatefulSets

具体配置

1. 配置文件

   apiVersion: v1
   kind: Service
   metadata:
     name: zk-hs
     namespace: prod
     labels:
       app: zk
   spec:
     ports:
     - port: 2888
       name: server
     - port: 3888
       name: leader-election
     clusterIP: None
     selector:
       app: zk
   ---
   apiVersion: v1
   kind: Service
   metadata:
     name: zk-cs
     namespace: prod
     labels:
       app: zk
   spec:
     ports:
     - port: 2181
       name: client
     selector:
       app: zk
   ---
   apiVersion: policy/v1beta1
   kind: PodDisruptionBudget
   metadata:
     name: zk-pdb
     namespace: prod
   spec:
     selector:
       matchLabels:
         app: zk
     maxUnavailable: 1
   ---
   apiVersion: apps/v1
   kind: StatefulSet
   metadata:
     name: prod-zk
     namespace: prod
   spec:
     selector:
       matchLabels:
         app: zk
     serviceName: zk-hs
     replicas: 3
     updateStrategy:
       type: RollingUpdate
     podManagementPolicy: OrderedReady
     template:
       metadata:
         labels:
           app: zk
       spec:
         tolerations:
           - operator: Exists
         affinity:
           nodeAffinity:
             requiredDuringSchedulingIgnoredDuringExecution:
               nodeSelectorTerms:
               - matchExpressions:
                 - key: kubernetes.io/resource
                   operator: In
                   values:
                   - prod-data
           podAntiAffinity:
             requiredDuringSchedulingIgnoredDuringExecution:
               - labelSelector:
                   matchExpressions:
                     - key: "app"
                       operator: In
                       values:
                       - zk
                 topologyKey: "kubernetes.io/hostname"
         containers:
         - name: prod-zk
           imagePullPolicy: Always
           image: "k8s.gcr.io/kubernetes-zookeeper:1.0-3.4.10"
           resources:
             requests:
               memory: "1Gi"
               cpu: "0.5"
             limits:
               cpu: "1"
               memory: "2Gi"
           ports:
           - containerPort: 2181
             name: client
           - containerPort: 2888
             name: server
           - containerPort: 3888
             name: leader-election
           command:
           - sh
           - -c
           - "start-zookeeper 
             --servers=3 
             --data_dir=/var/lib/zookeeper/data 
             --data_log_dir=/var/lib/zookeeper/data/log 
             --conf_dir=/opt/zookeeper/conf 
             --client_port=2181 
             --election_port=3888 
             --server_port=2888 
             --tick_time=2000 
             --init_limit=10 
             --sync_limit=5 
             --heap=512M 
             --max_client_cnxns=60 
             --snap_retain_count=3 
             --purge_interval=12 
             --max_session_timeout=40000 
             --min_session_timeout=4000 
             --log_level=INFO"
           readinessProbe:
             exec:
               command:
               - sh
               - -c
               - "zookeeper-ready 2181"
             initialDelaySeconds: 10
             timeoutSeconds: 5
           livenessProbe:
             exec:
               command:
               - sh
               - -c
               - "zookeeper-ready 2181"
             initialDelaySeconds: 10
             timeoutSeconds: 5
           volumeMounts:
           - name: datadir
             mountPath: /var/lib/zookeeper
         # 如果是简单的测试sattefulSet安装zookeeper集群，使用临时存储即可
         # StatefulSet 控制器为 StatefulSet 中的每个 Pod 生成一个 PersistentVolumeClaim
         #volumes:
         #- name: datadir
         #  emptyDir: {}
         securityContext:
           runAsUser: 1000
           fsGroup: 1000
     # 正式环境，需要部署持久化存储
     volumeClaimTemplates:
     - metadata:
         name: datadir
         annotations:
           volume.alpha.kubernetes.io/storage-class: anything
       spec:
         accessModes: [ "ReadWriteOnce" ]
         resources:
           requests:
             storage: 20Gi
         storageClassName: alicloud-disk-essd

2. 修改时区（lens编辑）

   # 时区调整
       volumeMounts:
   ...
               - name: localtime
                 mountPath: /etc/localtime
   ---------------------------------------------------
   
         volumes:
           - name: localtime
             hostPath:
               path: /etc/localtime
               type: ''