一、简介

前面详细介绍了pod的常用控制器replicaSet、deployment和DaemonSet，参考文章

Kubernetes/K8S基础使用方法总结【四】——Pod控制器

主要用来部署无状态应用。而对于有状态应用，常用的控制器为StatefulSet，

1.对于statefulSet的使用，有以下几点要求：

• 稳定且唯一的网络标识符；
• 稳定且持久的存储；
• 有序、平滑的进行部署和扩展；
• 有序、平滑地终止和删除；
• 有序的滚动更新；

2.StatefulSet包含三个重要组件

• headless service(无头服务)；
• StatefulSet控制器；
• volumeClaimTemplate(存储卷申请模板)

二、StatefulSet(简称sts)

1.创建sts实例：

apiVersion: v1
kind: Service
metadata:
  name: myapp
  labels:
    app: myapp
spec:
  ports:
  - port: 80
    name: web
  clusterIP: None
  selector:
    app: myapp-pod
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: myapp
spec:
  serviceName: myapp
  replicas: 3
  selector:
    matchLabels:
      app: myapp-pod
  template:
    metadata:
      labels:
        app: myapp-pod
    spec:
      containers:
      - name: myapp
        image: ikubernetes/myapp:v1
        ports:
        - containerPort: 80
          name: web
        volumeMounts:
        - name: myappdata
          mountPath: /usr/share/nginx/html
  volumeClaimTemplates:
  - metadata:
      name: myappdata
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 2Gi

2. 应用并查看sts信息

如下图显示3个pod资源已创建并就绪running状态

[root@master1 yaml]# kubectl apply -f stateFullSet-demo.yaml 
service/myapp created
statefulset.apps/myapp created
[root@master1 yaml]# kubectl get sts
NAME    READY   AGE
myapp   3/3     7m27s
[root@master1 yaml]# kubectl get pods
NAME                       READY   STATUS    RESTARTS   AGE
myapp-0                    1/1     Running   0          8m23s
myapp-1                    1/1     Running   0          108s
myapp-2                    1/1     Running   0          85s

3. 查看pv和pvc

如下显示被自动绑定，表示成功！

[root@master1 yaml]# kubectl get pv
NAME    CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                       STORAGECLASS   REASON   AGE
pv001   3Gi        RWO,RWX        Retain           Bound    default/myappdata-myapp-2                           25m
pv002   3Gi        RWO,RWX        Retain           Bound    default/myappdata-myapp-0                           25m
pv003   3Gi        RWO,RWX        Retain           Bound    default/myappdata-myapp-1                           25m
[root@master1 yaml]# kubectl get pvc
NAME                STATUS   VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
myappdata-myapp-0   Bound    pv002    3Gi        RWO,RWX                       9m12s
myappdata-myapp-1   Bound    pv003    3Gi        RWO,RWX                       2m37s
myappdata-myapp-2   Bound    pv001    3Gi        RWO,RWX                       2m14s

4.扩容

kubectl scale命令进行扩展和缩减

[root@master1 volumes]# kubectl scale sts myapp --replicas=2
statefulset.apps/myapp scaled

kubectl patch命令扩展和缩减

[root@master1 volumes]# kubectl patch sts myapp -p '{"spec":{"replicas":3}}'
statefulset.apps/myapp patched

5.版本升级