一、StorageClass
简介及属性
StorageClass提供了一种描述存储类（class）的方法，不同的class可能会映射到不同的服务质量等级和备份策略或其他策略等。
每个StorageClass 都包含 provisioner、parameters 和 reclaimPolicy 字段， 这些字段会在StorageClass需要动态分配 PersistentVolume 时会使用到。
StorageClass的属性
Provisioner（存储分配器）：用来决定使用哪个卷插件分配PV，该字段必须指定。可以指定内部分配器，也可以指定外部分配器。外部分配器的代码地址为：kubernetes-incubator/external-storage，其中包括NFS和Ceph等。
Reclaim Policy（回收策略）：通过reclaimPolicy字段指定创建的Persistent Volume的回收策略，回收策略包括：Delete 或者 Retain，没有指定默认为Delete。
更多属性查看：https://kubernetes.io/zh/docs/concepts/storage/storage-classes/
NFSClient Provisioner
NFSClient Provisioner是一个automatic provisioner，使用NFS作为存储，自动创建PV和对应的PVC，本身不提供NFS存储，需要外部先有一套NFS存储服务。
PV以namespace−namespace−{pvcName}-${pvName}的命名格式提供（在NFS服务器上）
PV回收的时候以 archieved-namespace−namespace−{pvcName}-${pvName} 的命名格式（在NFS服务器上）
二、NFS动态分配PV示例
实验准备
首先需要保证nfs服务器的正常运行：
[root@server1 ~]# showmount -e
Export list for server1:
/nfs *
授权配置
接下来进行基于角色的认证授权的配置：
[root@server1 pv]# mkdir nfsclass
[root@server1 pv]# cd nfsclass/
[root@server1 nfsclass]# vim rbac.yaml
[root@server1 nfsclass]# cat rbac.yaml
apiVersion: v1
kind: ServiceAccount
metadata:
name: nfs-client-provisioner
# replace with namespace where provisioner is deployed
namespace: default
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: nfs-client-provisioner-runner
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: ["create", "update", "patch"]
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: run-nfs-client-provisioner
subjects:
- kind: ServiceAccount
name: nfs-client-provisioner
# replace with namespace where provisioner is deployed
namespace: default
roleRef:
kind: ClusterRole
name: nfs-client-provisioner-runner
apiGroup: rbac.authorization.k8s.io
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: leader-locking-nfs-client-provisioner
# replace with namespace where provisioner is deployed
namespace: default
rules:
- apiGroups: [""]
resources: ["endpoints"]
verbs: ["get", "list", "watch", "create", "update", "patch"]
---
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: leader-locking-nfs-client-provisioner
# replace with namespace where provisioner is deployed
namespace: default
subjects:
- kind: ServiceAccount
name: nfs-client-provisioner
# replace with namespace where provisioner is deployed
namespace: default
roleRef:
kind: Role
name: leader-locking-nfs-client-provisioner
apiGroup: rbac.authorization.k8s.io
部署NFS Client Provisioner
[root@server1 nfsclass]# vim deployment.yaml
[root@server1 nfsclass]# cat deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: nfs-client-provisioner
labels:
app: nfs-client-provisioner
# replace with namespace where provisioner is deployed
namespace: default #指定为默认的namespace
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: nfs-client-provisioner:latest #镜像名称
volumeMounts:
- name: nfs-client-root
mountPath: /persistentvolumes
env:
- name: PROVISIONER_NAME
value: westos.org/nfs #分配器的名称
- name: NFS_SERVER
value: 172.25.63.1 #NFS服务器地址
- name: NFS_PATH
value: /nfs #nfs的输出路径
volumes:
- name: nfs-client-root #nfs卷
nfs:
server: 172.25.63.1
path: /nfs
其中需要的镜像nfs-client-provisioner:latest，可以先拉取下来然后上传到私有仓库，这样在部署的时候比较快。
创建 NFS SotageClass
[root@server1 nfsclass]# vim class.yaml
[root@server1 nfsclass]# cat class.yaml
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: managed-nfs-storage #SotageClass的名称
provisioner: westos.org/nfs #分配器的名称
parameters:
archiveOnDelete: "false"
其中：archiveOnDelete: "false"表示在删除时不会对数据进行打包，当设置为true时表示删除时会对数据进行打包。
运行部署文件
运行之前先将环境中的所有pv和pvc全部删除。
[root@server1 nfsclass]# kubectl get pv
No resources found in default namespace.
[root@server1 nfsclass]# kubectl get pvc
No resources found in default namespace.
然后可以使用以下命令直接运行通目录下的所有部署文件(rbac.yaml,deployment.yaml,class.yaml)：
[root@server1 nfsclass]# kubectl apply -f .
查看状态：
[root@server1 nfsclass]# kubectl get all
NAME READY STATUS RESTARTS AGE
pod/nfs-client-provisioner-6b66ddf664-zjvtv 1/1 Running 0 62s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 18d
service/myservice ClusterIP 10.101.31.155 <none> 80/TCP 14d
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/nfs-client-provisioner 1/1 1 1 63s
NAME DESIRED CURRENT READY AGE
replicaset.apps/nfs-client-provisioner-6b66ddf664 1 1 1 63s
此时并不会创建pv，但是会为我们创建一个sc（SotageClass）：
[root@server1 nfsclass]# kubectl get pv
No resources found in default namespace.
[root@server1 nfsclass]#
[root@server1 nfsclass]# kubectl get sc
NAME PROVISIONER RECLAIMPOLICY VOLUMEBINDINGMODE ALLOWVOLUMEEXPANSION AGE
managed-nfs-storage westos.org/nfs Delete Immediate false 76s
创建测试pvc
[root@server1 nfsclass]# vim pvc.yaml
[root@server1 nfsclass]# cat pvc.yaml
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: test-claim
annotations:
volume.beta.kubernetes.io/storage-class: "managed-nfs-storage"
spec:
accessModes:
- ReadWriteMany
resources:
requests:
storage: 100Mi
创建：
[root@server1 nfsclass]# kubectl apply -f pvc.yaml
persistentvolumeclaim/test-claim created
此时会为我们创建一个pv：
[root@server1 nfsclass]# kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-2a8ecd7a-a181-42dd-bae6-53ead083dcbc 100Mi RWX Delete Bound default/test-claim managed-nfs-storage 7s
创建pvc后会在nfs服务器的共享目录中生成以namespace+pvcname+pvname命名的文件夹：
[root@server1 nfsclass]# ls /nfs/
default-test-claim-pvc-2a8ecd7a-a181-42dd-bae6-53ead083dcbc
而当此时我们将pvc删除后，pv也会随之删除：
[root@server1 nfsclass]# kubectl delete -f pvc.yaml
persistentvolumeclaim "test-claim" deleted
[root@server1 nfsclass]# kubectl get pvc
No resources found in default namespace.
[root@server1 nfsclass]#
[root@server1 nfsclass]# kubectl get pv
No resources found in default namespace.
接下来我们将删除打包策略设置为true：
[root@server1 nfsclass]# vim class.yaml
[root@server1 nfsclass]# cat class.yaml
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: managed-nfs-storage
provisioner: westos.org/nfs
parameters:
archiveOnDelete: "true"
运行：
[root@server1 nfsclass]# kubectl delete -f class.yaml
storageclass.storage.k8s.io "managed-nfs-storage" deleted
[root@server1 nfsclass]# kubectl apply -f class.yaml
storageclass.storage.k8s.io/managed-nfs-storage created
[root@server1 nfsclass]#
[root@server1 nfsclass]# kubectl get sc
NAME PROVISIONER RECLAIMPOLICY VOLUMEBINDINGMODE ALLOWVOLUMEEXPANSION AGE
managed-nfs-storage westos.org/nfs Delete Immediate false 15s
再创建两个pvc：
[root@server1 nfsclass]# vim pvc.yaml
[root@server1 nfsclass]# cat pvc.yaml
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: test-claim
annotations:
volume.beta.kubernetes.io/storage-class: "managed-nfs-storage"
spec:
accessModes:
- ReadWriteMany
resources:
requests:
storage: 100Mi
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: test-claim-2
annotations:
volume.beta.kubernetes.io/storage-class: "managed-nfs-storage"
spec:
accessModes:
- ReadWriteMany
resources:
requests:
storage: 200Mi
[root@server1 nfsclass]#
[root@server1 nfsclass]# kubectl apply -f pvc.yaml
查看pv状态：
[root@server1 nfsclass]# kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-093922b7-048a-4c1f-97e9-d77afe0ec37b 200Mi RWX Delete Bound default/test-claim-2 managed-nfs-storage 12s
pvc-34761774-0a1f-4519-9d44-35c3736ce550 100Mi RWX Delete Bound default/test-claim managed-nfs-storage 2m9s
删除这些pv后再查看nfs共享目录：
[root@server1 nfsclass]# kubectl delete -f pvc.yaml
persistentvolumeclaim "test-claim" deleted
persistentvolumeclaim "test-claim-2" deleted
[root@server1 nfsclass]# kubectl get pv
No resources found in default namespace.
[root@server1 nfsclass]# ls /nfs/
archived-default-test-claim-2-pvc-093922b7-048a-4c1f-97e9-d77afe0ec37b
archived-default-test-claim-pvc-34761774-0a1f-4519-9d44-35c3736ce550
可以看出数据被打包成 archived+ 原来名字的形式。
创建测试pod
创建测试pod并修改pvc：
[root@server1 nfsclass]# vim pod.yaml
[root@server1 nfsclass]# cat pod.yaml
kind: Pod
apiVersion: v1
metadata:
name: test-pod
spec:
containers:
- name: test-pod
image: nginx
volumeMounts:
- name: nfs-pvc
mountPath: "/usr/share/nginx/html"
volumes:
- name: nfs-pvc
persistentVolumeClaim:
claimName: test-claim
[root@server1 nfsclass]#
[root@server1 nfsclass]# vim pvc.yaml
[root@server1 nfsclass]# cat pvc.yaml
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: test-claim
annotations:
volume.beta.kubernetes.io/storage-class: "managed-nfs-storage"
spec:
accessModes:
- ReadWriteMany
resources:
requests:
storage: 100Mi
[root@server1 nfsclass]#
[root@server1 nfsclass]#
[root@server1 nfsclass]# kubectl apply -f pvc.yaml
persistentvolumeclaim/test-claim created
[root@server1 nfsclass]#
[root@server1 nfsclass]# kubectl apply -f pod.yaml
pod/test-pod created
查看pod状态：
[root@server1 nfsclass]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nfs-client-provisioner-6b66ddf664-zjvtv 1/1 Running 0 15m 10.244.1.81 server2 <none> <none>
test-pod 1/1 Running 0 33s 10.244.2.70 server3 <none> <none>
此时访问这个pod不能访问到，提示403 Forbidden：
现在需要生成默认发布页面，可以直接在nfs共享目录中直接写入：
[root@server1 nfsclass]# ls /nfs/
default-test-claim-pvc-17f37558-e8da-4b92-9d11-3a0adab97d8b
[root@server1 nfsclass]#
[root@server1 nfsclass]# echo redhat > /nfs/default-test-claim-pvc-17f37558-e8da-4b92-9d11-3a0adab97d8b/index.html
再进行访问测试就可以访问到页面了：
[root@server1 nfsclass]# curl 10.244.2.70
redhat
查看pod挂载：
[root@server1 nfsclass]# kubectl describe pod test-pod
实验后删除：
[root@server1 nfsclass]# kubectl delete -f pod.yaml
[root@server1 nfsclass]# kubectl delete -f pvc.yaml
三、默认 StorageClass
默认的StorageClass 将被用于动态的为没有特定 storage class 需求的 PersistentVolumeClaims 配置存储：（只能有一个默认StorageClass）
如果没有默认StorageClass，PVC 也没有指定storageClassName 的值，那么意味着它只能够跟 storageClassName 也是“”的 PV 进行绑定。
如上例中的pvc若没有指定分配器的名称则会一直处于准备状态：
[root@server1 nfsclass]# vim pvc.yaml
[root@server1 nfsclass]# cat pvc.yaml
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: test-claim
# annotations:
# volume.beta.kubernetes.io/storage-class: "managed-nfs-storage"
spec:
accessModes:
- ReadWriteMany
resources:
requests:
storage: 100Mi
[root@server1 nfsclass]# kubectl get sc
NAME PROVISIONER RECLAIMPOLICY VOLUMEBINDINGMODE ALLOWVOLUMEEXPANSION AGE
managed-nfs-storage westos.org/nfs Delete Immediate false 12m
[root@server1 nfsclass]#
[root@server1 nfsclass]# kubectl apply -f pvc.yaml
persistentvolumeclaim/test-claim created
[root@server1 nfsclass]#
[root@server1 nfsclass]# kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
test-claim Pending 10s
[root@server1 nfsclass]# kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
test-claim Pending 12s
这种情况可以使用以下命令将之前创建的StorageClass设置为默认：
[root@server1 nfsclass]# kubectl patch storageclass managed-nfs-storage -p '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"true"}}}'
更改后再查看sc发现已经变成默认的sc：
之后再次运行pvc部署文件即可：
[root@server1 nfsclass]# kubectl delete -f pvc.yaml
persistentvolumeclaim "test-claim" deleted
[root@server1 nfsclass]# kubectl apply -f pvc.yaml
persistentvolumeclaim/test-claim created
[root@server1 nfsclass]#
[root@server1 nfsclass]# kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
test-claim Bound pvc-95e11d69-4199-43e3-9084-72e3ad0c36a9 100Mi RWX managed-nfs-storage 9s
可以看出pvc状态已经正常。