statefulset 管理的Pod是有序的，后缀是通过-1，-2等数字拼接而成
创建statefulset资源时，必须创建service
stafulset 管理的Pod资源，删除Pod并新建，新建的Pod和删除的Pod名称一致
statefulset具有volumeclaimtemplate这个字段，是卷申请模板，会自动创建pv、pvc
statefulset创建的Pod，具备域名： pod-name.svc-name.svc-namespace.svc.cluster.local

apiVersion: v1
kind: Service
metadata:
  name: nginx-test
  labels:
    app: redis-test
spec:
  ports:
  - port: 80
    name: web
  clusterIP: None
  selector:
    app: redis-test
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: web
spec:
  selector:
    matchLabels:
      app: redis-test
  serviceName: "nginx-test"
  replicas: 2
  template:
    metadata:
      labels:
        app: redis-test
    spec:
      containers:
      - name: nginx
        image: docker.io/library/nginx
        imagePullPolicy: IfNotPresent
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html/
        ports:
        - containerPort: 80
          name: web
  volumeClaimTemplates:
  - metadata:
      name: www
    spec:
      storageClassName: "nfs"
      accessModes: ['ReadWriteOnce']
      resources:
        requests:
          storage: 1Gi

apiVersion: v1
kind: Service
metadata:
  name: nginx-test
  labels:
    app: redis-test
spec:
  ports:
  - port: 80
    name: web
  selector:
    app: redis-test
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: web
spec:
  selector:
    matchLabels:
      app: redis-test
  serviceName: "nginx-test"
  updateStrategy:
    rollingUpdate:
      maxUnavailable: 0
      partition: 1      # 针对statefulset，更新序号为1的Pod
  replicas: 2
  template:
    metadata:
      labels:
        app: redis-test
    spec:
      containers:
      - name: nginx
        image: docker.io/janakiramm/myapp:v1
        imagePullPolicy: IfNotPresent
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html/
        ports:
        - containerPort: 80
          name: web
  volumeClaimTemplates:
  - metadata:
      name: www
    spec:
      storageClassName: "nfs"
      accessModes: ['ReadWriteOnce']
      resources:
        requests:
          storage: 1Gi