StatefulSet
有状态服务sts比较常见的mongo复制集 ，redis cluster，rabbitmq cluster等等，这些服务基本都会用StatefulSet模式来运行，当然除了这个，它们内部集群的关系还需要一系列脚本或controller来维系它们间的状态，这些会在后面进阶课程专门来讲，现在为了让大家先更好的明白StatefulSet，我这里直接还是用nginx服务来实战

一、准备好NFS服务器

确保nfs可以正常工作，创建持久化需要的目录。【前面的验证过程中已部署好NFS服务器这里直接引用】

path: /opt/data/nginx
server: 10.0.19.127

二、开启rbac权限

RBAC基于角色的访问控制–全拼Role-Based Access Control
根据rbac.yaml 文件创建Service Account

apiVersion: v1
kind: ServiceAccount #创建一个账户，主要用来管理NFS provisioner在k8s集群中运行的权限
metadata:
  name: nfs-client-provisioner
  namespace: kube-system

---
kind: ClusterRole  #创建集群角色
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: nfs-client-provisioner-runner #角色名
rules:  #角色权限
  - apiGroups: [""]
    resources: ["persistentvolumes"] # 操作的资源
    verbs: ["get", "list", "watch", "create", "delete"] # 对该资源的操作权限
  - apiGroups: [""]
    resources: ["persistentvolumeclaims"]
    verbs: ["get", "list", "watch", "update"]
  - apiGroups: ["storage.k8s.io"]
    resources: ["storageclasses"]
    verbs: ["get", "list", "watch"]
  - apiGroups: [""]
    resources: ["events"]
    verbs: ["list", "watch", "create", "update", "patch"]
  - apiGroups: [""]
    resources: ["endpoints"]
    verbs: ["get", "list", "watch", "create", "update", "patch"]

---
kind: ClusterRoleBinding # 集群角色绑定
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: run-nfs-client-provisioner
subjects:  # 角色绑定对象
  - kind: ServiceAccount
    name: nfs-client-provisioner
    namespace: kube-system 
roleRef:
  kind: ClusterRole # 集群角色
  name: nfs-client-provisioner-runner
  apiGroup: rbac.authorization.k8s.io

这个文件是创建授权账户。为什么要授权？在K8S中，我们知道有 ApiServer 组件，它可以管理我们创建的 deployment， pod，service等资源，但是有些资源它是管不到的，比如说 K8S本身运行需要的组件等等，同样StorageClass这种资源它也管不到，所以，需要授权账户。

我们在master节点执行

[root@k8s-master1 ~]# kubectl apply -f rbac.yaml 
serviceaccount/nfs-client-provisioner created
clusterrole.rbac.authorization.k8s.io/nfs-client-provisioner-runner created
clusterrolebinding.rbac.authorization.k8s.io/run-nfs-client-provisioner created

三、 创建StorageClass，指定provisioner

nfs-client-provisioner镜像包下载链接: https://pan.baidu.com/s/1jQc8pPj2piQjtaVG4od6UA?pwd=uu82
提取码: uu82 复制这段内容后打开百度网盘手机App，操作更方便哦

创建nfs-client-provisioner.yaml文件

kind: Deployment
apiVersion: apps/v1
metadata:
  name: nfs-provisioner-01
  namespace: kube-system #与RBAC文件中的namespace保持一致
spec:
  replicas: 1
  strategy:
    type: Recreate
  selector:
    matchLabels:
      app: nfs-provisioner-01
  template:
    metadata:
      labels:
        app: nfs-provisioner-01
    spec:
      serviceAccountName: nfs-client-provisioner # 指定serviceAccount!
      containers:
        - name: nfs-client-provisioner
          image: jmgao1983/nfs-client-provisioner:latest #镜像地址
          imagePullPolicy: IfNotPresent
          volumeMounts:  # 挂载数据卷到容器指定目录
            - name: nfs-client-root
              mountPath: /persistentvolumes   #不需要修改
          env:
            - name: PROVISIONER_NAME
              value: nfs-provisioner-01  # 此处供应者名字供storageclass调用
            - name: NFS_SERVER
              value: 10.0.19.127   # 填入NFS的地址
            - name: NFS_PATH
              value: /opt/data/nginx   # 填入NFS挂载的目录
      volumes:
        - name: nfs-client-root
          nfs:
            server: 10.0.19.127   # 填入NFS的地址
            path: /opt/data/nginx   # 填入NFS挂载的目录

---
apiVersion: storage.k8s.io/v1
kind: StorageClass  # 创建StorageClass
metadata:
  name: nfs-boge
provisioner: nfs-provisioner-01  #这里的名称要和provisioner配置文件中的环境变量PROVISIONER_NAME保持一致
# Supported policies: Delete、 Retain ， default is Delete
reclaimPolicy: Retain   #清除策略

PS：nfs-client-provisioner这个镜像的作用，它通过k8s集群内置的NFS驱动，挂载远端的NFS服务器到本地目录，然后将自身作为storageprovisioner，然后关联到storageclass资源。

在master上创建

[root@k8s-master1 ~]# kubectl apply -f nfs-client-provisioner1.yaml 
deployment.apps/nfs-provisioner-01 created
storageclass.storage.k8s.io/nfs-boge created

四、创建Service 和 StatefulSet和pvc

service的名称可以随意取，但是statefulset的名称已经定死了，为web，
StatefulSet创建的第一个Pod的name应该为web-0，第二个为web-1。
这里StatefulSet中的Pod与PVC之间的绑定关系是通过名称来匹配的，即：

PVC_name  =  volumeClaimTemplates_name + "-" + pod_name
www-web-0     =       www               + "-" +   web-0
www-web-1     =       www               + "-" +   web-1

root@node1:~# cat web.yaml 
apiVersion: v1
kind: Service
metadata:
  name: web-headless   #无头服务的名称
  namespace: nginx
  labels:
    app: nginx  
spec:
  ports:
  - port: 80
    name: web
  clusterIP: None
  selector:
    app: nginx
---

apiVersion: v1
kind: Service
metadata:
  name: web
  namespace: nginx
  labels:
    app: nginx
spec:
  ports:
  - port: 80
    name: web
  selector:
    app: nginx

---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: web
  namespace: nginx
spec:
  selector:
    matchLabels:
      app: nginx # has to match .spec.template.metadata.labels
  serviceName: "web-headless"   #填写无头服务的名称
  replicas: 2 # by default is 1
  template:
    metadata:
      labels:
        app: nginx # has to match .spec.selector.matchLabels
    spec:
      terminationGracePeriodSeconds: 10
      containers:
      - name: nginx
        image: nginx:1.8
        ports:
        - containerPort: 80
          name: web
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html
  volumeClaimTemplates:   #这步自动创建pvc
  - metadata:
      name: www
    spec:
      accessModes: [ "ReadWriteOnce" ]
      storageClassName: nfs-boge
      resources:
        requests:
          storage: 5Gi

五、测试

[root@k8s-master1 ~]# kubectl exec -it web-0 sh -n nginx 
# ping web-0.web-headless.nginx
PING web-0.web-headless.nginx.svc.cluster.local (10.244.0.102): 56 data bytes
64 bytes from 10.244.0.102: icmp_seq=0 ttl=64 time=0.025 ms
64 bytes from 10.244.0.102: icmp_seq=1 ttl=64 time=0.053 ms
64 bytes from 10.244.0.102: icmp_seq=2 ttl=64 time=0.042 ms
^C--- web-0.web-headless.nginx.svc.cluster.local ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.025/0.040/0.053/0.000 ms
# ping web-1.web-headless.nginx
PING web-1.web-headless.nginx.svc.cluster.local (10.244.1.80): 56 data bytes
64 bytes from 10.244.1.80: icmp_seq=0 ttl=62 time=0.401 ms
64 bytes from 10.244.1.80: icmp_seq=1 ttl=62 time=0.313 ms
64 bytes from 10.244.1.80: icmp_seq=2 ttl=62 time=0.369 ms
^C--- web-1.web-headless.nginx.svc.cluster.local ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.313/0.361/0.401/0.036 ms

有状态服务好处
1、pod名不变
2、pod直接可以通过 pod名.svc名.namespace名 ；进行通信