Use a PVC to mount a disk to an Elastic Container Instance-based pod - Elastic Container Instance

Disks are block-level storage products provided by Alibaba Cloud. Disks feature low latency, high performance, high durability, and high reliability. After you install an Alibaba Cloud Container Storage Interface (CSI) plugin, you can mount disks on self-managed Kubernetes clusters as volumes. You can use a PersistentVolumeClaim (PVC) to mount disks as statically or dynamically provisioned volumes. This topic describes how to use a PVC to mount a disk to an Elastic Container Instance pod.

Prerequisites

A VNode is deployed in a self-managed Kubernetes cluster.
The version of the self-managed Kubernetes cluster is v1.16 or later, and the CSI-Provisioner component is deployed on the self-managed Kubernetes cluster.
Important
For information about how to deploy the CSI-Provisioner component, see alibaba-cloud-csi-driver. If an issue occurs when you deploy the component, submit the issue on GitHub.
If the self-managed Kubernetes cluster is deployed in a data center, the data center is connected to Alibaba Cloud.

Precautions

Before you mount a disk, take note of the following items:

Disks cannot be shared. You can mount a disk to only one pod.
You can mount a disk only to an Elastic Container Instance pod on a VNode that resides in the same zone as the disk.

Mount a disk as a statically provisioned volume

Create a disk.
1. Log on to the Elastic Compute Service (ECS) console.
2. In the region and zone in which the VNode resides, create a pay-as-you-go disk.
  For information about how to create a disk, see Create a disk. After the disk is created, record the ID of the disk.
  Note
  If you use an existing disk, make sure that the disk resides in the same region and zone as the VNode and that the disk is not partitioned and formatted.

Create a PersistentVolume (PV).

Create a file named static-disk-pv.yaml and copy the following template content into the file. Modify the parameters in the template as required.

apiVersion: v1
kind: PersistentVolume
metadata:
  name: static-disk-pv
  labels:
    alicloud-pvname: static-disk-pv
spec:
  capacity:
    storage: 25Gi
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  csi:
    driver: diskplugin.csi.alibabacloud.com
    volumeHandle: "<your disk-id>"     # Replace <your disk-id> with the ID of your disk.
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: topology.diskplugin.csi.alibabacloud.com/zone
          operator: In
          values:
          - "<your-node-zone-id>"   # Replace with the ID of the zone where the VNode resides.

The following table describes the parameters in the template.

Parameter	Description
driver	The type of the driver used. In this example, the parameter is set to `diskplugin.csi.alibabacloud.com`. This indicates that the CSI plug-in provided by Alibaba Cloud for disks is used.
volumeHandle	The ID of the disk.

Run the following command to create a PV:
```
kubectl create -f static-disk-pv.yaml
```

Create a PVC.

Create a file named static-disk-pvc.yaml and copy the following template content into the file.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: static-disk-pvc
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 25Gi
  selector:
    matchLabels:
      alicloud-pvname: static-disk-pv

Run the following command to create a PVC:
```
kubectl create -f static-disk-pvc.yaml
```

Mount the disk to an Elastic Container Instance pod.

Create a file named static-disk-test.yaml and copy the following template content into the file.

apiVersion: v1
kind: Pod
metadata:
  name: static-disk-test
  labels:
    alibabacloud.com/eci: "true"
spec:
  nodeSelector:
    k8s.aliyun.com/vnode: "true"
  tolerations:
  - key: k8s.aliyun.com/vnode
    operator: "Equal"
    value: "true"
    effect: "NoSchedule"
  containers:
  - name: nginx
    image: registry-vpc.cn-beijing.aliyuncs.com/eci_open/nginx:1.14.2
    ports:
    - containerPort: 80
      name: web
    volumeMounts:
    - name: pvc-disk
      mountPath: /data
  volumes:
    - name: pvc-disk
      persistentVolumeClaim:
        claimName: static-disk-pvc

Run the following command to create a pod:
```
kubectl create -f static-disk-test.yaml
```

View the result.

kubectl get pods -o wide

Expected output:

NAME                 READY   STATUS    RESTARTS   AGE   IP            NODE                                  NOMINATED NODE   READINESS GATES
static-disk-test     1/1     Running   0          44s   172.16.XX.XX   cn-beijing.vnd-2ze8nd8xcl33t4pa****   <none>           <none>

Check the file directories in the pod and verify that the /data mount directory is generated for the disk.

静态云盘csi

Mount a disk as a dynamically provisioned volume

Create a StorageClass.

Create a file named disk-sc.yaml and copy the following template content into the file. Modify the parameters in the template as required.

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: alicloud-disk-essd
provisioner: diskplugin.csi.alibabacloud.com
parameters:
  type: cloud_essd
  regionId: cn-beijing 
  zoneId: cn-beijing-l 
  fstype: ext4
  readonly: "true"
  mkfsOptions: "-O project,quota"
  diskTags: "key1:value1,key2:value2"
  encrypted: "false"
  performanceLevel: PL1
volumeBindingMode: Immediate
reclaimPolicy: Delete
allowVolumeExpansion: true

The following table describes the parameters in the template.

Parameter	Description
provisioner	The type of the driver used. In this example, the parameter is set to `diskplugin.csi.alibabacloud.com`. This indicates that the CSI plug-in provided by Alibaba Cloud for disks is used.
type	The category of the disk. Valid values: cloud_essd: enhanced SSD (ESSD). cloud_ssd: standard SSD. cloud_efficiency: ultra disk. available: The system first tries to create a standard SSD. If no standard SSD is available in the zone, the system creates an ultra disk. Note You can set this parameter to any combination of cloud_essd, cloud_ssd, and cloud_efficiency. For example, you can set this parameter to `type: cloud_efficiency, cloud_ssd, cloud_essd`. In this case, the system tries to create a disk of a specified type in sequence. The system stops trying to create a disk after a disk is created.
regionId and zoneId	The region and zone in which the disk resides. The disk must reside in the same region and zone as the VNode.
fstype	The file system of the disk. Default value: ext4.
readonly	Specifies whether the automatically created disk is read-only. Default value: false. true: The disk is read-only. false: The disk is readable and writable.
mkfsOptions	The options that are specified to format the disk. Example: `mkfsOptions: "-O project,quota"`.
diskTags	The tags of the disk. Format: `key1:value1,key2:value2`.
encrypted	Specifies whether to encrypt the disk. Default value: false.
performanceLevel	The performance level (PL) of the disk. This parameter is valid only if the category of the disk is ESSD. Valid values: PL0, PL1, PL2, and PL3. For more information, see ESSDs.
volumeBindingMode	The binding mode of the disk. Default value: Immediate, which indicates that the system creates a disk before it creates a pod.
reclaimPolicy	The reclaim policy of the disk. Default value: Delete. Valid values: Delete: When the PVC is deleted, the related PV and disk are also deleted. Retain: When the PVC is deleted, the related PV and disk are retained and can only be manually deleted. If you have high requirements for data security, we recommend that you apply the Retain policy to the disk to prevent data loss caused by errors.
allowVolumeExpansion	Specifies whether to automatically scale up the disk.

Run the following command to create a StorageClass:
```
kubectl create -f disk-sc.yaml
```

Create a PVC.

Create a file named disk-pvc.yaml and copy the following template content into the file.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: disk-pvc
spec:
  accessModes:
  - ReadWriteOnce
  volumeMode: Filesystem
  resources:
    requests:
      storage: 25Gi
  storageClassName: alicloud-disk-essd

Run the following command to create a PVC:
```
kubectl create -f disk-pvc.yaml
```
The system automatically creates a disk and the related PV based on the StorageClass configurations.

Mount the disk to an Elastic Container Instance pod.

Create a file named disk-test.yaml and copy the following template content into the file.

Note

We recommend that you create a StatefulSet instead of a Deployment to mount a disk. Deployments are used to manage stateless applications. When a pod is restarted, the start time of the next start may be earlier than the end time of the previous start. If multiple pods are created for a Deployment, no dedicated volume is provisioned for each pod.

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: disk-test
spec:
  selector:
    matchLabels:
      app: nginx
  serviceName: "nginx"
  template:
    metadata:
      labels:
        app: nginx
    spec:
      nodeSelector:    
        k8s.aliyun.com/vnode: "true"
      tolerations:     
      - key: k8s.aliyun.com/vnode
        operator: "Equal"
        value: "true"
        effect: "NoSchedule"
      containers:
      - name: nginx
        image: registry-vpc.cn-beijing.aliyuncs.com/eci_open/nginx:1.14.2
        ports:
        - containerPort: 80
          name: web
        volumeMounts:
        - name: pvc-disk
          mountPath: /data
      volumes:
        - name: pvc-disk
          persistentVolumeClaim:
            claimName: disk-pvc

Run the following command to create a StatefulSet:
```
kubectl create -f disk-test.yaml
```

View the result.

kubectl get pods -o wide

Expected output:

NAME                              READY   STATUS              RESTARTS   AGE     IP             NODE                                  NOMINATED NODE   READINESS GATES
disk-test-0                       1/1     Running             0          3m58s   172.16.XX.XX   cn-beijing.vnd-2ze8nd8xcl33t4pa****   <none>           <none>

Check the file directories in the pod and verify that the /data mount directory is generated for the disk.

csi动态云盘