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Community Blog How to Use NAS Persistent Volumes Dynamically in a Kubernetes Cluster

How to Use NAS Persistent Volumes Dynamically in a Kubernetes Cluster

In this article, we will introduce a solution for dynamically generating a NAS volume in a Kubernetes cluster on Alibaba Cloud.

By Kan Junbao

1. Introduction

The solution for dynamically generating a NAS volume introduced in this article: On an existing file system, a directory is automatically generated, which is defined as the target volume;

Image address: registry.cn-hangzhou.aliyuncs.com/acs/alicloud-nas-controller:v1.11.5.4-433631d-aliyun

Resources generated by default:

Name of the generated PV: pvc-${pvc-uid}

Name of the generated Directory: namespace-pvcname-pvname

The following declaration can be made in the annotations of the PVC to customize the name:

The generated PV and directory name are defined below.

  annotations:
    pv-name-created: replace-user-id

2. Deploy the NAS Controller

Create alicloud-nas-controller to implement dynamic provider nas pv;

Create alicloud-nas storageclass to provide a template for nas pv provision;

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: alicloud-nas
provisioner: alicloud/nas
reclaimPolicy: Delete
parameters:
  drivertype: flexvolume
  nfsversion: "4.0"
  options: ""

---
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
  name: alicloud-nas-controller
  namespace: kube-system
spec:
  replicas: 1 
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: alicloud-nas-controller
    spec:
      tolerations:
      - effect: NoSchedule
        operator: Exists
        key: node-role.kubernetes.io/master
      - effect: NoSchedule
        operator: Exists
        key: node.cloudprovider.kubernetes.io/uninitialized
      serviceAccount: admin
      containers:
        - name: alicloud-nas-controller
          image: registry.cn-hangzhou.aliyuncs.com/acs/alicloud-nas-controller:v1.11.5.4-433631d-aliyun
          imagePullPolicy: Always
          volumeMounts:
          - mountPath: /persistentvolumes
            name: nfs-client-root
          env:
            - name: NFS_SERVER
              value: 154154b095-**.cn-beijing.nas.aliyuncs.com
            - name: NFS_PATH
              value: /
      volumes:
      - name: nfs-client-root
        flexVolume:
          driver: alicloud/nas
          options:
            path: /
            server: 154154b095-**.cn-beijing.nas.aliyuncs.com
            vers: "4.0"

StorageClass usage instructions:

drivertype: used to indicate the storage type of the generated PV. NFS and Flexvolume are available.
    nfs: the default option, indicating that the K8S native NFS driver is used for mounting;
    flexvolume: indicates that the Flexvolume NAS driver provided by Alibaba Cloud is used for mounting;

nfsversion: the version used to mount NAS, and 3 and 4.0 are supported. The default is 4.0;
    When drivertype is Flexvolume, it is configured here;
When drivertype is NFS, it is configured through mountOptions;

options: configurable options for mounting NFS;
    When drivertype is Flexvolume, it is configured here;
When drivertype is NFS, it is configured through mountOptions;

StorageClass example:

 ## Use the NFS driver provided by Kubernetes, and configure mountOptions. The reclaimPolicy is Delete;
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: alicloud-nas-nfs
mountOptions:
- vers=4.0
- noresvport
provisioner: alicloud/nas
reclaimPolicy: Delete

## Use the Flexvolume NAS driver provided by Alibaba Cloud to configure the NAS version and options;
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: alicloud-nas-flex
provisioner: alicloud/nas
reclaimPolicy: Delete
parameters:
  drivertype: flexvolume
  nfsversion: "3"
  options: "noresvport"

3. Create an application - Deployment:

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: replace-user-id
  annotations:
    pv-name-created: replace-user-id
spec:
  storageClassName: alicloud-nas
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 5Gi
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: "deploy-nas"
spec:
  replicas: 1 
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: deploy-nas
    spec:
      containers:
        - name: "nginx"
          image: "nginx"
          volumeMounts:
              - name: pvc-nas
                mountPath: "/data"
      volumes:
      - name: pvc-nas
        persistentVolumeClaim:
            claimName: replace-user-id

Run:
# userID="hello-123"
# cat deploy.yaml | sed  "s/replace-user-id/\"$userID\"/g" | kubectl create -f -

# kubectl get pod | grep deploy-nas
deploy-nas-85696b6bfc-t5dmh         1/1       Running          0          28m

# kubectl get pvc | grep hell
hello-123       Bound     hello-123                                  5Gi        RWX            alicloud-nas-flex   28m

# kubectl get pv | grep hell
hello-123                                  5Gi        RWX            Delete           Bound      default/hello-123       alicloud-nas-flex                       28m

# View the generated directory under the NAS directory:
# ls -l | grep hello
drwxrwxrwx  2 root root 4096 Feb 19 09:58 hello-123

4. Create an application - StatefulSet:

If volumeTemplateClaim is used, pv-name-created is not supported to configure the PV name;

apiVersion: v1
kind: Service
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  ports:
  - port: 80
    name: web
  clusterIP: None
  selector:
    app: nginx
---
apiVersion: apps/v1beta1
kind: StatefulSet
metadata:
  name: web
spec:
  replicas: 2
  serviceName: "nginx"
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:alpine
        volumeMounts:
        - mountPath: "/data"
          name: pvc-sts
  volumeClaimTemplates:
  - metadata:
      name: pvc-sts
    spec:
      accessModes:
        - ReadWriteOnce
      storageClassName: alicloud-nas-flex
      resources:
        requests:
          storage: 2Gi
          
View the application after creation:
# kubectl get pod | grep web
web-0                               1/1       Running          0          7s
web-1                               1/1       Running          0          4s

# kubectl get pvc | grep web
pvc-sts-web-0   Bound     pvc-65ab251a-33ec-11e9-a151-00163e066784   2Gi        RWO            alicloud-nas-flex   13m
pvc-sts-web-1   Bound     pvc-8437c50e-33ed-11e9-a151-00163e066784   2Gi        RWO            alicloud-nas-flex   5m

# kubectl get pv | grep web
pvc-65ab251a-33ec-11e9-a151-00163e066784   2Gi        RWO            Delete           Bound      default/pvc-sts-web-0   alicloud-nas-flex                       13m
pvc-8437c50e-33ed-11e9-a151-00163e066784   2Gi        RWO            Delete           Bound      default/pvc-sts-web-1   alicloud-nas-flex                       5m

# View the generated directory under the NAS directory:
# ls -l | grep sts
drwxrwxrwx  2 root root 4096 Feb 19 10:16 default-pvc-sts-web-0-pvc-65ab251a-33ec-11e9-a151-00163e066784
drwxrwxrwx  2 root root 4096 Feb  19 10:24 default-pvc-sts-web-1-pvc-8437c50e-33ed-11e9-a151-00163e066784

5. Create an application - Pod:

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: replace-user-id
  annotations:
    pv-name-created: replace-user-id 
spec:
  storageClassName: alicloud-nas-flex
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 5Gi
---
apiVersion: v1
kind: Pod
metadata:
  name: "nas-pod"
spec:
  containers:
    - name: "nginx"
      image: "nginx"
      volumeMounts:
          - name: pvc-nas
            mountPath: "/data"
  volumes:
  - name: pvc-nas
    persistentVolumeClaim:
        claimName: replace-user-id
       
# userID="pod-123"
# cat pod.yaml | sed  "s/replace-user-id/\"$userID\"/g" | kubectl create -f -

# kubectl get pod | grep pod
nas-pod                             1/1       Running          0          32s

# kubectl get pvc | grep pod
pod-123         Bound     pod-123                                    5Gi        RWX            alicloud-nas-flex   44s

# kubectl get pv | grep pod
pod-123                                    5Gi        RWX            Delete           Bound      default/pod-123         alicloud-nas-flex                       48s

# ls -l | grep pod
drwxrwxrwx  2 root root 4096 Feb 19 10:54 pod-123
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