Kubernetes PV 动态供给（StorageClass）
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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.
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
