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Kubernetes PV 动态供给（StorageClass）

21 12月
作者:admin|分类:容器虚拟化

PV静态供给明显的缺点是维护成本太高了！因此，K8s开始支持PV动态供给，使用StorageClass对象实现。

Storgess帮你创建pvc，只需要在pvc里面定义使用哪个storgeclass，storgess可以标志使用什么存储比如nfs ceph。 并不是所有存储支持storgess，有的需要插件

支持动态供给的存储插件：https://kubernetes.io/docs/concepts/storage/storage-classes/

Provisioner

Each StorageClass has a provisioner that determines what volume plugin is used for provisioning PVs. This field must be specified.

Volume Plugin Internal Provisioner Config Example
AWSElasticBlockStore AWS EBS
AzureFile Azure File
AzureDisk Azure Disk
CephFS - -
Cinder OpenStack Cinder
FC - -
FlexVolume - -
Flocker -
GCEPersistentDisk GCE PD
Glusterfs Glusterfs
iSCSI - -
Quobyte Quobyte
NFS - NFS
RBD Ceph RBD
VsphereVolume vSphere
PortworxVolume Portworx Volume
ScaleIO ScaleIO
StorageOS StorageOS
Local - Local

NFS  

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: example-nfs
provisioner: example.com/external-nfs
parameters:
  server: nfs-server.example.com
  path: /share
  readOnly: false
  • server: Server is the hostname or IP address of the NFS server.
  • path: Path that is exported by the NFS server.
  • readOnly: A flag indicating whether the storage will be mounted as read only (default false).

Kubernetes doesn't include an internal NFS provisioner. You need to use an external provisioner to create a StorageClass for NFS. Here are some examples:

PV 动态供给（StorageClass）

                                                                                                                                                                                                        基于NFS实现PV动态供给流程图

[root@k8s-master nfs-client]# ls
class.yaml  deployment.yaml  rbac.yaml
[root@k8s-master nfs-client]# kubectl apply -f .



[root@k8s-master nfs-client]# cat deployment.yaml 
apiVersion: v1
kind: ServiceAccount
metadata:
  name: nfs-client-provisioner
---
kind: Deployment
apiVersion: apps/v1 
metadata:
  name: nfs-client-provisioner
spec:
  replicas: 1
  strategy:
    type: Recreate
  selector:
    matchLabels:
      app: nfs-client-provisioner
  template:
    metadata:
      labels:
        app: nfs-client-provisioner
    spec:
      serviceAccountName: nfs-client-provisioner
      containers:
        - name: nfs-client-provisioner
          image: quay.io/external_storage/nfs-client-provisioner:latest
          volumeMounts:
            - name: nfs-client-root
              mountPath: /persistentvolumes
          env:
            - name: PROVISIONER_NAME
              value: fuseim.pri/ifs
            - name: NFS_SERVER
              value: 192.168.179.102 
            - name: NFS_PATH
              value: /ifs/kubernetes
      volumes:
        - name: nfs-client-root
          nfs:
            server: 192.168.179.102
            path: /ifs/kubernetes




[root@k8s-master ~]# kubectl get pod,svc
NAME                                         READY   STATUS    RESTARTS   AGE
pod/nfs-client-provisioner-855d45d4f-l5h9w   1/1     Running   0          4m58s

 部署NFS实现自动创建PV插件：

  • git clone https://github.com/kubernetes-incubator/external-storage
  • cd nfs-client/deploy
  • kubectl apply -f rbac.yaml # 授权访问apiserver
  • kubectl apply -f deployment.yaml # 部署插件，需修改里面NFS服务器地址与共享目录
  • kubectl apply -f class.yaml # 创建存储类

当前申请的pv请求会给到storageClass，storageClass会将请求交给之前创建的扩展插件处理，自动创建pv，也就是不需要手工创建pv 

[root@k8s-master ~]# cat deployment-sc.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: deployment-sc
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx-sc
  template:
    metadata:
      labels:
        app: nginx-sc
    spec:
      containers:
      - name: nginx
        image: nginx
        volumeMounts:
        - name: wwwroot
          mountPath: /usr/share/nginx/html
        ports:
        - containerPort: 80
      volumes:
      - name: wwwroot
        persistentVolumeClaim:
          claimName: my-pvc3

---

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-pvc3
spec:
  storageClassName: "managed-nfs-storage"
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 18Gi



[root@k8s-master nfs-client]# kubectl get pv
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM            STORAGECLASS          REASON   AGE
pvc-d033b273-a2c2-4c78-bd7e-074114a32ee6   18Gi       RWX            Delete           Bound    default/my-pvc   managed-nfs-storage            88s


[root@k8s-master nfs-client]# kubectl get pvc
NAME     STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS          AGE
my-pvc   Bound    pvc-d033b273-a2c2-4c78-bd7e-074114a32ee6   18Gi       RWX            managed-nfs-storage   98s


[root@k8s-master nfs-client]# kubectl get sc
NAME                  PROVISIONER      RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
managed-nfs-storage   fuseim.pri/ifs   Delete          Immediate           false                  4m


[root@k8s-master nfs-client]# kubectl get pod -o wide
NAME                                      READY   STATUS    RESTARTS   AGE     IP               NODE        NOMINATED NODE   READINESS GATES
deployment-sc-c5d6db95-95xt4              1/1     Running   0          7m17s   10.244.36.77     k8s-node1   <none>           <none>
deployment-sc-c5d6db95-g4vrh              1/1     Running   0          7m17s   10.244.169.141   k8s-node2   <none>           <none>
deployment-sc-c5d6db95-g5cwx              1/1     Running   0          7m17s   10.244.169.140   k8s-node2   <none>           <none>
nfs-client-provisioner-776769c5c7-2zx55   1/1     Running   0          8m16s   10.244.169.139   k8s-node2   <none>           <none>

 这个目录实际上就是插件帮你创建的，这个目录就是为一组pod提供存储(目录名称为pvc名字+pv名字)

[root@reg ~]# cd /ifs/kubernetes/
[root@reg kubernetes]# ls
default-my-pvc-pvc-d033b273-a2c2-4c78-bd7e-074114a32ee6
[root@reg kubernetes]# cd default-my-pvc-pvc-d033b273-a2c2-4c78-bd7e-074114a32ee6/
[root@reg default-my-pvc-pvc-d033b273-a2c2-4c78-bd7e-074114a32ee6]# ls
[root@reg default-my-pvc-pvc-d033b273-a2c2-4c78-bd7e-074114a32ee6]# echo "default my-mypvc" >> index.html


[root@k8s-master nfs-client]# curl 10.244.169.140
default my-mypvc

当你使用了delete回收策略，当pvc删除，对应的pv也会删除，并且之前的数据会被清理 

[root@k8s-master nfs-client]# kubectl delete -f deployment-sc.yaml 
deployment.apps "deployment-sc" deleted
persistentvolumeclaim "my-pvc" deleted
[root@k8s-master nfs-client]# kubectl get pvc,pv
No resources found

后端并没有被删除，将之前的目录做了一个归档，如果不想要归档设置存储类 

[root@k8s-master nfs-client]# vim class.yaml 
archiveOnDelete: "false"
[root@reg ~]# cd /ifs/kubernetes/
[root@reg kubernetes]# ls
archived-default-my-pvc-pvc-d033b273-a2c2-4c78-bd7e-074114a32ee6
[root@reg kubernetes]# ls archived-default-my-pvc-pvc-d033b273-a2c2-4c78-bd7e-074114a32ee6/
index.html

总结

pvc匹配pv 容量匹配 访问模式匹配

你可能的疑问？

Q：PV与PVC什么关系？

A：一对一

Q：PVC与PV怎么匹配的？

A：访问模式和存储容量

Q：容量匹配策略

A：匹配就近的符合的容量（向上）

Q：存储容量是真的用于限制吗？

A：存储容量取决于后端存储，容量字段主要还是用于匹配

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