Statefulset
StatefulSet是为了解决有状态服务的问题，对应的Deployment和ReplicaSet是为了无状态服务而设计，其应用场景包括：
稳定的持久化存储，即Pod重新调度后还是能访问到相同的持久化数据，基于PVC来实现
有序部署，有序扩展，即Pod是有顺序的，在部署或者扩展的时候要依据定义的顺序依次依次进行（即从0到N-1，在下一个Pod运行之前所有之前的Pod必须都是Running和Ready状态），基于init containers来实现
有序收缩，有序删除（即从N-1到0）
因为statefulset要求Pod的名称是有顺序的，每一个Pod都不能被随意取代，也就是即使Pod重建之后，名称依然不变。为后端的每一个Pod去命名。
从上面的应用场景可以发现，StatefulSet由以下几部分组成：
用于定义网络标志的Headless Service（headless-svc：无头服务。因为没有IP地址，所以它不具备负载均衡的功能了。）
用于创建PersistentVolumes的volumeClaimTemplates
定义具体应用的StatefulSet
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StatefulSet：Pod控制器。RC、RS、Deployment、DS。 无状态的服务。
template（模板）：根据模板创建出来的Pod，它们的状态都是一模一样的（除了名称、IP、域名之外）可以理解为：任何一个Pod，都可以被删除，然后用新生成的Pod进行替换。
有状态的服务：需要记录前一次或者多次通信中的相关时间，以作为下一次通信的分类标准。比如：MySQL等数据库服务。（Pod的名称，不能随意变化。数据持久化的目录也是不一样，每一个Pod都有自己独有的数据持久化存储目录。）
每一个Pod-----对应一个PVC-----每一个PVC对应一个PV。
用statefuset资源运行一个httpd web服务，要求3个Pod，但是每个Pod的主界面内容不一样，并且都要做专有的数据持久化，尝试删除其中一个Pod，查看新生成的Pod，是否数据与之前一致。
基于NFS服务，创建NFS服务。 ? [root@master ~]# yum -y install nfs-utils rpcbind br/>2.[root@master ~]# mkdir /nfsdata [root@master ~]# vim /etc/exports br/>4./nfsdata *(rw,sync,no_root_squash) [root@master ~]# systemctl start nfs-server.service [root@master ~]# systemctl start rpcbind br/>7.[root@master ~]# showmount -e Export list for master: ./nfsdata *
2.创建RBAC权限
vim rbac-rolebind.yaml
apiVersion: v1 kind: Namespace metadata: name: lbs-test apiVersion: v1 kind: ServiceAccount 创建rbac授权用户。及定义权限 metadata: name: nfs-provisioner name：lbs-test --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRole metadata: name: nfs-provisioner-runner name：lbs-test rules: - apiGroups: [""] resources: ["persistentvolumes"] verbs: ["get", "list", "watch", "create", "delete"] - apiGroups: [""] resources: ["persistentvolumeclaims"] verbs: ["get", "list", "watch", "update"] - apiGroups: ["storage.k8s.io"] resources: ["storageclasses"] verbs: ["get", "list", "watch"] - apiGroups: [""] resources: ["events"] verbs: ["watch", "create", "update", "patch"] - apiGroups: [""] resources: ["services", "endpoints"] verbs: ["get","create","list", "watch","update"] - apiGroups: ["extensions"] resources: ["podsecuritypolicies"] resourceNames: ["nfs-provisioner verbs: ["use"] --- kind: ClusterRoleBinding apiVersion: rbac.authorization.k8s.io/v1 metadata: name: run-nfs-provisioner subjects: - kind: ServiceAccount name: nfs-provisioner namespace: lbs-test 如没有名称空间需要添加这个default默认否则报错 roleRef: kind: ClusterRole name: nfs-provisioner-runner apiGroup: rbac.authorization.k8s.io
执行yaml文件：
[root@master yaml]# kubectl apply -f rbac-rolebind.yaml namespace/lbh-test created serviceaccount/nfs-provisioner created clusterrole.rbac.authorization.k8s.io/nfs-provisioner-runner created clusterrolebinding.rbac.authorization.k8s.io/run-nfs-provisioner created
3.创建Deployment资源对象
[root@master yaml]# vim nfs-deployment.yaml apiVersion: extensions/v1beta1 kind: Deployment metadata: name: nfs-client-provisioner name：lbs-test spec: replicas: 1#副本数量为1 strategy: type: Recreate#重置 template: metadata: labels: app: nfs-client-provisioner spec: serviceAccount: nfs-provisioner#指定账户 containers: - name: nfs-client-provisioner image: registry.cn-hangzhou.aliyuncs.com/open-ali/nfs-client-provisioner使用的是这个镜像。 volumeMounts: - name: nfs-client-root mountPath: /persistentvolumes#指定容器内的挂载目录 env: - name: PROVISIONER_NAME#容器内置变量 value: bdqn#这是变量的名字 - name: NFS_SERVER value: 192.168.1.1 - name: NFS_PATH#指定Nfs的共享目录 value: /nfsdata volumes:#指定挂载到容器内的nfs路径与IP - name: nfs-client-root nfs: server: 192.168.1.1 path: /nfsdata
执行yaml文件，查看Pod
[root@master yaml]# kubectl apply -f nfs-deployment.yaml deployment.extensions/nfs-client-provisioner created [root@master yaml]# kubectl get pod -n lbs-test NAME READY STATUS RESTARTS AGE nfs-client-provisioner-5d88975f6d-wdbnc 1/1 Running 0 13s
4.创建Storageclass资源对象（sc）：
root@master yaml]# vim sc.yaml apiVersion: storage.k8s.io/v1 kind: StorageClass metadata: name: sc-nfs namespace：lbs-test #名称空间 名 provisioner: lbs-test#与deployment资源的env环境变量value值相同 reclaimPolicy: Retain #回收策略
执行yaml文件，查看SC
[root@master yaml]# kubectl apply -f sc.yaml storageclass.storage.k8s.io/sc-nfs created [root@master yaml]# kubectl get sc -n lbs-test NAME PROVISIONER AGE sc-nfs lbs-test 8s
5.创建StatefulSet资源对象，自动创建PVC：
vim statefulset.yaml apiVersion: v1 kind: Service metadata: name: headless-svc namespace: lbs-test labels: app: headless-svc spec: ports: - port: 80 name: myweb selector: app: headless-pod clusterIP: None --- apiVersion: apps/v1 kind: StatefulSet metadata: name: statefulset-test namespace: lbs-test spec: serviceName: headless-svc replicas: 3 selector: matchLabels: app: headless-pod template: metadata: labels: app: headless-pod spec: containers: - image: httpd name: myhttpd ports: - containerPort: 80 name: httpd volumeMounts: - mountPath: /mnt name: test volumeClaimTemplates: 这个字段：自动创建PVC - metadata: name: test annotations: //这是指定storageclass，名称要一致 volume.beta.kubernetes.io/storage-class: sc-nfs spec: accessModes: - ReadWriteOnce resources: requests: storage: 100Mi
执行yaml文件，查看Pod：
[root@master yaml]# kubectl apply -f statefulset.yaml service/headless-svc created statefulset.apps/statefulset-test created [root@master yaml]# kubectl get pod -n lbs-test NAME READY STATUS RESTARTS AGE nfs-client-provisioner-5d88975f6d-wdbnc 1/1 Running 0 22m statefulset-test-0 1/1 Running 0 8m59s statefulset-test-1 1/1 Running 0 2m30s statefulset-test-2 1/1 Running 0 109s
查看是否自动创建PV及PVC
PV：
[root@master yaml]# kubectl get pv -n lbs-test NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE pvc-0454e9ad-892f-4e39-8dcb-79664f65d1e5 100Mi RWO Delete Bound lbh-test/test-statefulset-test-2 sc-nfs 4m23s pvc-2cb98c60-977f-4f3b-ba97-b84275f3b9e5 100Mi RWO Delete Bound lbh-test/test-statefulset-test-0 sc-nfs 11m pvc-99137753-ccd0-4524-bf40-f3576fc97eba 100Mi RWO Delete Bound lbh-test/test-statefulset-test-1 sc-nfs 5m4s
PVC：
[root@master yaml]# kubectl get pvc -n lbs-test NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE test-statefulset-test-0 Bound pvc-2cb98c60-977f-4f3b-ba97-b84275f3b9e5 100Mi RWO sc-nfs 13m test-statefulset-test-1 Bound pvc-99137753-ccd0-4524-bf40-f3576fc97eba 100Mi RWO sc-nfs 6m42s test-statefulset-test-2 Bound pvc-0454e9ad-892f-4e39-8dcb-79664f65d1e5 100Mi RWO sc-nfs 6m1s
查看是否创建持久化目录：
[root@master yaml]# ls /nfsdata/ lbh-test-test-statefulset-test-0-pvc-2cb98c60-977f-4f3b-ba97-b84275f3b9e5 lbh-test-test-statefulset-test-1-pvc-99137753-ccd0-4524-bf40-f3576fc97eba lbh-test-test-statefulset-test-2-pvc-0454e9ad-892f-4e39-8dcb-79664f65d1e5
6.在pod资源内创建数据。并访问测试。
[root@master yaml]# cd /nfsdata/ [root@master nfsdata]# echo 111 > lbs-test-test-statefulset-test-0-pvc-2cb98c60-977f-4f3b-ba97-b84275f3b9e5/index.html [root@master nfsdata]# echo 222 > lbs-test-test-statefulset-test-1-pvc-99137753-ccd0-4524-bf40-f3576fc97eba/index.html [root@master nfsdata]# echo 333 > lbs-test-test-statefulset-test-2-pvc-0454e9ad-892f-4e39-8dcb-79664f65d1e5/index.html [root@master nfsdata]# kubectl get pod -o wide -n lbs-test NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES nfs-client-provisioner-5d88975f6d-wdbnc 1/1 Running 0 30m 10.244.2.2 node02 <none> <none> statefulset-test-0 1/1 Running 0 17m 10.244.1.2 node01 <none> <none> statefulset-test-1 1/1 Running 0 10m 10.244.2.3 node02 <none> <none> statefulset-test-2 1/1 Running 0 9m57s 10.244.1.3 node01 <none> <none> [root@master nfsdata]# curl 10.244.1.2 111 [root@master nfsdata]# curl 10.244.2.3 222 [root@master nfsdata]# curl 10.244.1.3 333
7.删除其中一个pod，查看该pod资源的数据是否会重新创建并存在。
[root@master ~]# kubectl get pod -n lbs-test NAME READY STATUS RESTARTS AGE nfs-client-provisioner-5d88975f6d-wdbnc 1/1 Running 0 33m statefulset-test-0 1/1 Running 0 20m statefulset-test-1 1/1 Running 0 13m statefulset-test-2 1/1 Running 0 13m [root@master ~]# kubectl delete pod -n lbs-test statefulset-test-0 pod "statefulset-test-0" deleted
删除后会重新创建pod资源
[root@master ~]# kubectl get pod -n lbs-test -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES nfs-client-provisioner-5d88975f6d-wdbnc 1/1 Running 0 35m 10.244.2.2 node02 <none> <none> statefulset-test-0 1/1 Running 0 51s 10.244.1.4 node01 <none> <none> statefulset-test-1 1/1 Running 0 15m 10.244.2.3 node02 <none> <none> statefulset-test-2 1/1 Running 0 14m 10.244.1.3 node01 <none> <none>
数据依旧存在
[root@master ~]# curl 10.244.1.4 111 [root@master ~]# cat /nfsdata/lbs-test-test-statefulset-test-0-pvc-2cb98c60-977f-4f3b-ba97-b84275f3b9e5/index.html 111
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StatefulSet资源对象，针对有状态的服务的数据持久化测试完成。
k8s数据持久化之statefulset的数据持久化，并自动创建PV与PVC
原文：https://www.cnblogs.com/douhua7458/p/13340596.html