介绍
动态挂载方式是指在应用中显式声明PVC，并在PVC中声明StorageClass；这时应用会通过Storageclass中指定的Provisioner来自动创建云盘，并自动生成云盘PV资源类型；
使用动态云盘需要满足以下条件：
集群中要部署云盘Provisioner服务，实现自动创建云盘；
创建预期使用storageclass资源，并指定云盘Provisioner；
在PVC中显式声明使用哪个storageclass；
无需显式创建PV，而是通过Provisioner自动创建；
无需在ecs控制台购买云盘，在应用部署时自动购买的情况；
云盘Provisioner
使用云盘动态卷的一个前提是系统中已经部署了云盘Provisioner。
K8S集群会默认部署Provisioner，Provisioner创建云盘需要对云盘有操作权限，可以通过AK、或STS token来获取权限；
配置AK：在部署Provisioner的时候设置ACCESS_KEY_ID、ACCESS_KEY_SECRET环境变量，可以配置ak；
配置STS：为默认方式，可以给集群（Master节点）授予RAM权限，详情参看RAM权限管理；
下面yaml文件为部署Provisioner的详细描述：
---
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: alicloud-disk-common
provisioner: alicloud/disk
parameters:
type: cloud
---
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: alicloud-disk-efficiency
provisioner: alicloud/disk
parameters:
type: cloud_efficiency
---
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: alicloud-disk-ssd
provisioner: alicloud/disk
parameters:
type: cloud_ssd
---
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: alicloud-disk-available
provisioner: alicloud/disk
parameters:
type: available
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
name: alicloud-disk-controller-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: ["list", "watch", "create", "update", "patch"]
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: alicloud-disk-controller
namespace: kube-system
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
name: run-alicloud-disk-controller
subjects:
- kind: ServiceAccount
name: alicloud-disk-controller
namespace: kube-system
roleRef:
kind: ClusterRole
name: alicloud-disk-controller-runner
apiGroup: rbac.authorization.k8s.io
---
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
name: alicloud-disk-controller
namespace: kube-system
spec:
replicas: 1
strategy:
type: Recreate
template:
metadata:
labels:
app: alicloud-disk-controller
spec:
tolerations:
- effect: NoSchedule
operator: Exists
key: node-role.kubernetes.io/master
- effect: NoSchedule
operator: Exists
key: node.cloudprovider.kubernetes.io/uninitialized
nodeSelector:
node-role.kubernetes.io/master: ""
serviceAccount: alicloud-disk-controller
containers:
- name: alicloud-disk-controller
image: registry.cn-hangzhou.aliyuncs.com/acs/alicloud-disk-controller:v1.10.4-f431fd8
volumeMounts:
- name: cloud-config
mountPath: /etc/kubernetes/
- name: logdir
mountPath: /var/log/alicloud/
volumes:
- name: cloud-config
hostPath:
path: /etc/kubernetes/
- name: logdir
hostPath:
path: /var/log/alicloud/StorageClass
阿里云K8S系统初始化的时候会默认创建4个StorageClass，这4个StorageClass适合在集群类型为单一zone的情况，若为多zone部署的集群，则需要自己另行创建；
alicloud-disk-common：创建普通云盘。
alicloud-disk-efficiency：创建高效云盘。
alicloud-disk-ssd：创建SSD云盘。
alicloud-disk-available：提供高可用选项，先试图创建高效云盘；如果相应AZ的高效云盘资源售尽，再试图创建SSD盘；如果SSD售尽，则试图创建普通云盘。
下面yaml描述了创建Storageclass的细节：
kind: StorageClass
apiVersion: storage.k8s.io/v1beta1
metadata:
name: alicloud-disk-common-hangzhou-b
provisioner: alicloud/disk
reclaimPolicy: Retain
parameters:
type: cloud_ssd
regionid: cn-hangzhou
zoneid: cn-hangzhou-b
fstype: "ext4"
readonly: "false"
encrypted: "true"reclaimPolicy：表示创建pv的回收策略，支持Delete、Retain两个类型，默认为Delete；这里需要注意：配置为Delete时，删除PVC后云盘一起被删除，数据不可恢复。
type: 表示创建什么类型的云盘，支持cloud、cloud_efficiency、cloud_ssd、available类型；
regionid：表示创建云盘所在region；
zoneid：表示创建云盘所在zone；
fstype：表示云盘使用的文件系统，可选项，默认为ext4；
readonly：表示挂载的读写权限是否为只读，可选项，默认为false；
encrypted：是否创建加密云盘，可选项，默认为false；
使用动态卷创建应用
部署一下应用模板，在PVC中显式指定storageClassName为上述创建的StorageClass；
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: disk-ssd
spec:
accessModes:
- ReadWriteOnce
storageClassName: alicloud-disk-ssd-beijing-b
resources:
requests:
storage: 20Gi
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-dynamic
labels:
app: nginx
spec:
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx
volumeMounts:
- name: disk-pvc
mountPath: "/data"
volumes:
- name: disk-pvc
persistentVolumeClaim:
claimName: disk-ssd验证高可用
创建应用
# kubectl create -f dynamic.yaml
# kubectl get pod | grep dynamic
nginx-dynamic-69f9bd7b8c-58sbs 1/1 Running 0 3m
# kubectl exec nginx-dynamic-69f9bd7b8c-58sbs df | grep data
/dev/vdb 20511312 45080 19401272 1% /data
在云盘中创建文件：
# kubectl exec nginx-dynamic-69f9bd7b8c-58sbs ls /data
lost+found
# kubectl exec nginx-dynamic-69f9bd7b8c-58sbs touch /data/dynamic
# kubectl exec nginx-dynamic-69f9bd7b8c-58sbs ls /data
dynamic
lost+found
删除Pod，验证文件持久化：
# kubectl delete pod nginx-dynamic-69f9bd7b8c-58sbs
pod "nginx-dynamic-69f9bd7b8c-58sbs" deleted
# kubectl get pod
NAME READY STATUS RESTARTS AGE
nginx-dynamic-69f9bd7b8c-58sbs 0/1 Terminating 0 5m
nginx-dynamic-69f9bd7b8c-ddcbb 0/1 ContainerCreating 0 2s
# kubectl exec nginx-dynamic-69f9bd7b8c-ddcbb ls /data
dynamic
lost+found