Using an Existing OBS Bucket Through a Static PV_Cloud Container Engine

Prerequisites

You have created a cluster and installed the CSI add-on (everest) in the cluster.
If you want to create a cluster using commands, use kubectl to connect to the cluster. For details, see Connecting to a Cluster Using kubectl.
You have created an OBS bucket. An OBS bucket of the parallel file system type can be selected only when it is in the same region as the cluster.

Constraints

When parallel file systems and object buckets are used, the group and permission of the mount point cannot be modified.
CCE allows you to use OBS parallel file systems by calling the OBS SDK or mounting a PVC through the obsfs tool provided by OBS. Each time an OBS parallel file system is mounted, an obsfs resident process is generated, as shown in the following figure.
Figure 1 obsfs resident process

Reserve 1 GiB of memory for each obsfs process. For example, for a node with 4 vCPUs and 8 GiB of memory, the obsfs parallel file system should be mounted to no more than eight pods.

An obsfs resident process runs on a node. If the consumed memory exceeds the upper limit of the node, the node malfunctions. On a node with 4 vCPUs and 8 GiB of memory, if more than 100 pods are mounted to parallel file systems, the node will be unavailable. Control the number of pods mounted to parallel file systems on a single node.

Multiple PVs can use the same OBS storage volume with the following restrictions:
- If multiple PVCs/PVs use the same underlying object storage volume, when you attempt to mount the volume to the same pod, the operation will fail because the volumeHandle values of these PVs are the same.
- The persistentVolumeReclaimPolicy parameter in the PVs must be set to Retain. Otherwise, when a PV is deleted, the associated underlying volume may be deleted. In this case, other PVs associated with the underlying volume malfunction.
- When the underlying volume is repeatedly used, enable isolation and protection for ReadWriteMany at the application layer to prevent data overwriting and loss.

Using an Existing OBS Bucket on the Console

Log in to the CCE console and click the cluster name to access the cluster console.

Statically create a PVC and PV.

Choose Storage from the navigation pane, and click the PersistentVolumeClaims (PVCs) tab. Click Create PVC in the upper right corner. In the dialog box displayed, configure the PVC parameters.

Parameter	Description
PVC Type	In this section, select OBS.
PVC Name	Enter the PVC name, which must be unique in the same namespace.
Creation Method	If underlying storage is available, create a storage volume or use an existing storage volume to statically create a PVC based on whether a PV has been created. If no underlying storage is available, select Dynamically provision. For details, see Using an OBS Bucket Through a Dynamic PV. In this example, select Create new to create a PV and PVC at the same time on the console.
PV^a	Select an existing PV volume in the cluster. Create a PV in advance. For details, see "Creating a storage volume" in Related Operations. You do not need to specify this parameter in this example.
OBS^b	Click Select OBS. On the displayed page, select the OBS bucket that meets your requirements and click OK. NOTE: Currently, only parallel file systems are supported.
PV Name^b	Enter the PV name, which must be unique in the same cluster.
Access Mode^b	OBS volumes support only ReadWriteMany, indicating that a storage volume can be mounted to multiple nodes in read/write mode. For details, see Volume Access Modes.
Reclaim Policy^b	You can select Delete or Retain to specify the reclaim policy of the underlying storage when the PVC is deleted. For details, see PV Reclaim Policy. NOTE: If multiple PVs use the same OBS volume, use Retain to avoid cascading deletion of underlying volumes.
Secret^b	Custom: Customize a secret if you want to assign different user permissions to different OBS storage devices. For details, see Using a Custom Access Key (AK/SK) to Mount an OBS Volume. Only secrets with the secret.kubernetes.io/used-by = csi label can be selected. The secret type is cfe/secure-opaque. If no secret is available, click Create Secret to create one. Name: Enter a secret name. Namespace: Select the namespace where the secret is. Access Key (AK/SK): Upload a key file in .csv format. For details, see Obtaining an Access Key.
Mount Options^b	Enter the mounting parameter key-value pairs. For details, see Configuring OBS Mount Options.

a: The parameter is available when Creation Method is set to Use existing.

b: The parameter is available when Creation Method is set to Create new.

Click Create to create a PVC and a PV.
You can choose Storage in the navigation pane and view the created PVC and PV on the PersistentVolumeClaims (PVCs) and PersistentVolumes (PVs) tab pages.

Create an application.

In the navigation pane on the left, click Workloads. In the right pane, click the Deployments tab.

Click Create Workload in the upper right corner. On the displayed page, click Data Storage in the Container Settings area and click Add Volume to select PVC.

Mount and use storage volumes, as shown in Table 1. For details about other parameters, see Workloads.

**Table 1** Mounting a storage volume
Parameter	Description
PVC	Select an existing object storage volume.
Mount Path	Enter a mount path, for example, /tmp. This parameter indicates the container path to which a data volume will be mounted. Do not mount the volume to a system directory such as / or /var/run. Otherwise, containers will be malfunctional. Mount the volume to an empty directory. If the directory is not empty, ensure that there are no files that affect container startup. Otherwise, the files will be replaced, causing container startup failures or workload creation failures. NOTICE: If a volume is mounted to a high-risk directory, use an account with minimum permissions to start the container. Otherwise, high-risk files on the host machine may be damaged.
Subpath	Enter a subpath, for example, tmp, indicating that data in the mount path of the container will be stored in the tmp folder of the volume. A subpath is used to mount a local volume so that the same data volume is used in a single pod. If this parameter is left blank, the root path is used by default.
Permission	Read-only: You can only read the data in the mounted volumes. Read/Write: You can modify the data volumes mounted to the path. Newly written data is not migrated if the container is migrated, which may cause data loss.

In this example, the disk is mounted to the /data path of the container. The container data generated in this path is stored in the OBS volume.

After the configuration, click Create Workload.
After the workload is created, the data in the container mount directory will be persistently stored. Verify the storage by referring to PV Reclaim Policy.

(kubectl) Using an Existing OBS Bucket

Use kubectl to connect to the cluster.

Create a PV.

Create the pv-obs.yaml file.

apiVersion: v1
kind: PersistentVolume
metadata:
  annotations:
    pv.kubernetes.io/provisioned-by: everest-csi-provisioner
    everest.io/reclaim-policy: retain-volume-only      # (Optional) The PV is deleted while the underlying volume is retained.
  name: pv-obs       # PV name.
spec:
  accessModes:
  - ReadWriteMany    # Access mode. The value must be ReadWriteMany for OBS.
  capacity:
    storage: 1Gi     # OBS volume capacity.
  csi:
    driver: obs.csi.everest.io        # Dependent storage driver for the mounting.
    driver: obs.csi.everest.io        # Instance type.
    volumeHandle: <your_volume_id>    # Name of the OBS volume.
    volumeAttributes:
      storage.kubernetes.io/csiProvisionerIdentity: everest-csi-provisioner
      everest.io/obs-volume-type: STANDARD
      everest.io/region: <your_region>                        # Region where the OBS volume is.
      everest.io/enterprise-project-id: <your_project_id>     # (Optional) Enterprise project ID. If an enterprise project is specified, use the same enterprise project when creating a PVC. Otherwise, the PVC cannot be bound to a PV.
    nodePublishSecretRef:            # Custom secret of the OBS volume.
      name: <your_secret_name>       # Custom secret name.
      namespace: <your_namespace>    # Namespace of the custom secret.
  persistentVolumeReclaimPolicy: Retain    # Reclaim policy.
  storageClassName: csi-obs               # Storage class name.
  mountOptions: []                         # Mount options.

**Table 2** Key parameters
Parameter	Mandatory	Description
everest.io/reclaim-policy: retain-volume-only	No	Optional. Currently, only retain-volume-only is supported. This field is valid only when the everest version is 1.2.9 or later and the reclaim policy is Delete. If the reclaim policy is Delete and the current value is retain-volume-only, the associated PV is deleted while the underlying storage volume is retained, when a PVC is deleted.
fsType	Yes	Instance type. The value can be obsfs or s3fs. obsfs: Parallel file system, which is mounted using obsfs (recommended). s3fs: Object bucket, which is mounted using s3fs.
volumeHandle	Yes	OBS volume name.
everest.io/obs-volume-type	Yes	OBS storage class. If fsType is set to s3fs, STANDARD (standard bucket) and WARM (infrequent access bucket) are supported. This parameter is invalid when fsType is set to obsfs.
everest.io/region	Yes	Region where the OBS bucket is deployed. For details about the value of region, see Regions and Endpoints.
everest.io/enterprise-project-id	No	Optional. Enterprise project ID of OBS. If an enterprise project is specified, specify the same enterprise project when creating a PVC. Otherwise, the PVC cannot be bound to a PV. How to obtain: On the OBS console, choose Buckets or Parallel File Systems in the navigation pane on the left. Click the name of the OBS bucket to access its details page. In the Basic Information area, locate the enterprise project and click it to access the enterprise project console. Copy the corresponding ID to obtain the ID of the enterprise project to which the object storage belongs.
nodePublishSecretRef	No	Access key (AK/SK) used for mounting the object storage volume. You can use the AK/SK to create a secret and mount it to the PV. For details, see Using a Custom Access Key (AK/SK) to Mount an OBS Volume. An example is as follows: nodePublishSecretRef: name: secret-demo namespace: default
mountOptions	No	Mount options. For details, see Configuring OBS Mount Options.
persistentVolumeReclaimPolicy	Yes	A reclaim policy is supported when the cluster version is or later than 1.19.10 and the everest version is or later than 1.2.9. The Delete and Retain reclaim policies are supported. For details, see PV Reclaim Policy. If multiple PVs use the same OBS volume, use Retain to avoid cascading deletion of underlying volumes. Delete: If everest.io/reclaim-policy is not specified, both the PV and storage resources are deleted when a PVC is deleted. If everest.io/reclaim-policy is set to retain-volume-only, when a PVC is deleted, the PV is deleted but the storage resources are retained. Retain: When a PVC is deleted, the PV and underlying storage resources are not deleted. Instead, you must manually delete these resources. After that, the PV is in the Released status and cannot be bound to the PVC again.
storage	Yes	Storage capacity, in Gi. For OBS buckets, this field is used only for verification (cannot be empty or 0). Its value is fixed at 1, and any value you set does not take effect for OBS buckets.
storageClassName	Yes	The storage class name of OBS volumes is csi-obs.

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

Create a PVC.

Create the pvc-obs.yaml file.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-obs
  namespace: default
  annotations:
    volume.beta.kubernetes.io/storage-provisioner: everest-csi-provisioner
    everest.io/obs-volume-type: STANDARD
    csi.storage.k8s.io/fstype: obsfs
    csi.storage.k8s.io/node-publish-secret-name: <your_secret_name>  # Custom secret name.
    csi.storage.k8s.io/node-publish-secret-namespace: <your_namespace>        # Namespace of the custom secret.
    everest.io/enterprise-project-id: <your_project_id>     # (Optional) Enterprise project ID. If an enterprise project is specified, use the same enterprise project when creating a PVC. Otherwise, the PVC cannot be bound to a PV.
spec:
  accessModes:
  - ReadWriteMany                  # The value must be ReadWriteMany for OBS.
  resources:
    requests:
      storage: 1Gi
  storageClassName: csi-obs       # Storage class name, which must be the same as that of the PV.
  volumeName: pv-obs    # PV name.

**Table 3** Key parameters
Parameter	Mandatory	Description
csi.storage.k8s.io/node-publish-secret-name	No	Name of the custom secret specified in the PV.
csi.storage.k8s.io/node-publish-secret-namespace	No	Namespace of the custom secret specified in the PV.
everest.io/enterprise-project-id	No	Project ID of OBS. How to obtain: On the OBS console, choose Buckets or Parallel File Systems in the navigation pane on the left. Click the name of the OBS bucket to access its details page. In the Basic Information area, locate the enterprise project and click it to access the enterprise project console. Copy the corresponding ID to obtain the ID of the enterprise project to which the object storage belongs.
storage	Yes	Requested capacity in the PVC, in Gi. For OBS, this field is used only for verification (cannot be empty or 0). Its value is fixed at 1, and any value you set does not take effect for OBS.
storageClassName	Yes	Storage class name, which must be the same as the storage class of the PV in 1. The storage class name of OBS volumes is csi-obs.
volumeName	Yes	PV name, which must be the same as the PV name in 1.

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

Create an application.

Create a file named web-demo.yaml. In this example, the OBS volume is mounted to the /data path.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web-demo
  namespace: default
spec:
  replicas: 2
  selector:
    matchLabels:
      app: web-demo
  template:
    metadata:
      labels:
        app: web-demo
    spec:
      containers:
      - name: container-1
        image: nginx:latest
        volumeMounts:
        - name: pvc-obs-volume    #Volume name, which must be the same as the volume name in the volumes field.
          mountPath: /data  #Location where the storage volume is mounted.
      imagePullSecrets:
        - name: default-secret
      volumes:
        - name: pvc-obs-volume    #Volume name, which can be customized.
          persistentVolumeClaim:
            claimName: pvc-obs    #Name of the created PVC.

Run the following command to create an application to which the OBS volume is mounted:
```
kubectl apply -f web-demo.yaml
```
After the workload is created, you can try Verifying Data Persistence and Sharing.

Verifying Data Persistence and Sharing

View the deployed applications and files.
1. Run the following command to view the created pod:
```
kubectl get pod | grep web-demo
```
  Expected output:
```
web-demo-846b489584-mjhm9   1/1     Running   0             46s
web-demo-846b489584-wvv5s   1/1     Running   0             46s
```
2. Run the following commands in sequence to view the files in the /data path of the pods:
```
kubectl exec web-demo-846b489584-mjhm9 -- ls /data
kubectl exec web-demo-846b489584-wvv5s -- ls /data
```
  If no result is returned for both pods, no file exists in the /data path.
Run the following command to create a file named static in the /data path:
```
kubectl exec web-demo-846b489584-mjhm9 --  touch /data/static
```
Run the following command to view the files in the /data path:
```
kubectl exec web-demo-846b489584-mjhm9 -- ls /data
```
Expected output:
```
static
```
Verify data persistence.
1. Run the following command to delete the pod named web-demo-846b489584-mjhm9:
```
kubectl delete pod web-demo-846b489584-mjhm9
```
  Expected output:
```
pod "web-demo-846b489584-mjhm9" deleted
```
  After the deletion, the Deployment controller automatically creates a replica.
2. Run the following command to view the created pod:
```
kubectl get pod | grep web-demo
```
  The expected output is as follows, in which web-demo-846b489584-d4d4j is the newly created pod:
```
web-demo-846b489584-d4d4j   1/1     Running   0             110s
web-demo-846b489584-wvv5s    1/1     Running   0             7m50s
```
3. Run the following command to check whether the files in the /data path of the new pod have been modified:
```
kubectl exec web-demo-846b489584-d4d4j -- ls /data
```
  Expected output:
```
static
```
  If the static file still exists, the data can be stored persistently.
Verify data sharing.
1. Run the following command to view the created pod:
```
kubectl get pod | grep web-demo
```
  Expected output:
```
web-demo-846b489584-d4d4j   1/1     Running   0             7m
web-demo-846b489584-wvv5s   1/1     Running   0             13m
```
2. Run the following command to create a file named share in the /data path of either pod: In this example, select the pod named web-demo-846b489584-d4d4j.
```
kubectl exec web-demo-846b489584-d4d4j --  touch /data/share
```
  Check the files in the /data path of the pod.
```
kubectl exec web-demo-846b489584-d4d4j -- ls /data
```
  Expected output:
```
share
static
```
3. Check whether the share file exists in the /data path of another pod (web-demo-846b489584-wvv5s) as well to verify data sharing.
```
kubectl exec web-demo-846b489584-wvv5s -- ls /data
```
  Expected output:
```
share
static
```
  After you create a file in the /data path of a pod, if the file is also created in the /data path of another pods, the two pods share the same volume.

Related Operations

You can also perform the operations listed in Table 4.

**Table 4** Related operations
Operation	Description	Procedure
Creating a storage volume (PV)	Create a PV on the CCE console.	Choose Storage from the navigation pane, and click the PersistentVolumes (PVs) tab. Click Create Volume in the upper right corner. In the dialog box displayed, configure the parameters. Volume Type: Select OBS. OBS: Click Select OBS. On the displayed page, select the OBS storage that meets your requirements and click OK. PV Name: Enter the PV name, which must be unique in the same cluster. Access Mode: SFS volumes support only ReadWriteMany, indicating that a storage volume can be mounted to multiple nodes in read/write mode. For details, see Volume Access Modes. Reclaim Policy: Delete or Retain. For details, see PV Reclaim Policy. NOTE: If multiple PVs use the same underlying storage volume, use Retain to prevent the underlying volume from being deleted with a PV. Custom: Customize a secret if you want to assign different user permissions to different OBS storage devices. For details, see Using a Custom Access Key (AK/SK) to Mount an OBS Volume. Only secrets with the secret.kubernetes.io/used-by = csi label can be selected. The secret type is cfe/secure-opaque. If no secret is available, click Create Secret to create one. Mount Options: Enter the mounting parameter key-value pairs. For details, see Configuring OBS Mount Options. Click Create.
Updating an access key	Update the access key of object storage on the CCE console.	Choose Storage from the navigation pane, and click the PersistentVolumeClaims (PVCs) tab. Click More > Update Access Key in the Operation column of the PVC. Upload a key file in .csv format. For details, see Obtaining an Access Key. Click OK. NOTE: After a global access key is updated, all pods mounted with the object storage that uses this access key can be accessed only after being restarted.
Viewing events	You can view event names, event types, number of occurrences, Kubernetes events, first occurrence time, and last occurrence time of the PVC or PV.	Choose Storage from the navigation pane, and click the PersistentVolumeClaims (PVCs) or PersistentVolumes (PVs) tab. Click View Events in the Operation column of the target PVC or PV to view events generated within one hour (event data is retained for one hour).
Viewing a YAML file	You can view, copy, and download the YAML files of a PVC or PV.	Choose Storage from the navigation pane, and click the PersistentVolumeClaims (PVCs) or PersistentVolumes (PVs) tab. Click View YAML in the Operation column of the target PVC or PV to view or download the YAML.

Using an Existing OBS Bucket Through a Static PV