Dynamically create and use a persistent volume with Azure Blob storage in Azure Kubernetes Service (AKS)

Container-based applications often need to access and persist data in an external data volume. If multiple pods need concurrent access to the same storage volume, you can use Azure Blob storage to connect using blobfuse or Network File System (NFS).

This article shows you how to install the Container Storage Interface (CSI) driver and dynamically create an Azure Blob storage container to attach to a pod in AKS.

For more information on Kubernetes volumes, see Storage options for applications in AKS.

Before you begin

• This article assumes that you have an existing AKS cluster running version 1.21 or higher. If you need an AKS cluster, see the AKS quickstart using the Azure CLI, using Azure PowerShell, or using the Azure portal.

• If you don't have a storage account that supports the NFS v3 protocol, review NFS v3 support with Azure Blob storage.

• Enable the Blob storage CSI driver (preview) on your AKS cluster.

Dynamic provisioning parameters

Create a persistent volume claim using built-in storage class

A persistent volume claim (PVC) uses the storage class object to dynamically provision an Azure Blob storage container. The following YAML can be used to create a persistent volume claim 5 GB in size with ReadWriteMany access, using the built-in storage class. For more information on access modes, see the Kubernetes persistent volume documentation.

1. Create a file named blob-nfs-pvc.yaml and copy in the following YAML.

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: azure-blob-storage
     annotations:
           volume.beta.kubernetes.io/storage-class: azureblob-nfs-premium
   spec:
     accessModes:
     - ReadWriteMany
     storageClassName: my-blobstorage
     resources:
       requests:
         storage: 5Gi
   

2. Create the persistent volume claim with the kubectl create command:

   kubectl create -f blob-nfs-pvc.yaml
   

Once completed, the Blob storage container will be created. You can use the kubectl get command to view the status of the PVC:

kubectl get pvc azure-blob-storage

The output of the command resembles the following example:

NAME                 STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS                AGE
azure-blob-storage   Bound    pvc-b88e36c5-c518-4d38-a5ee-337a7dda0a68   5Gi        RWX            azureblob-nfs-premium       92m

Use the persistent volume claim

The following YAML creates a pod that uses the persistent volume claim azure-blob-storage to mount the Azure Blob storage at the `/mnt/blob' path.

1. Create a file named blob-nfs-pv, and copy in the following YAML. Make sure that the claimName matches the PVC created in the previous step.

   kind: Pod
   apiVersion: v1
   metadata:
     name: mypod
   spec:
     containers:
     - name: mypod
       image: mcr.azk8s.cn/oss/nginx/nginx:1.17.3-alpine
       resources:
         requests:
           cpu: 100m
           memory: 128Mi
         limits:
           cpu: 250m
           memory: 256Mi
       volumeMounts:
       - mountPath: "/mnt/blob"
         name: volume
     volumes:
       - name: volume
         persistentVolumeClaim:
           claimName: azure-blob-storage
   

2. Create the pod with the kubectl apply command:

   kubectl apply -f blob-nfs-pv.yaml
   

3. After the pod is in the running state, run the following command to create a new file called test.txt.

   kubectl exec mypod -- touch /mnt/blob/test.txt
   

4. To validate the disk is correctly mounted, run the following command, and verify you see the test.txt file in the output:

   kubectl exec mypod -- ls /mnt/blob
   

   The output of the command resembles the following example:

   test.txt
   

Create a custom storage class

The default storage classes suit the most common scenarios, but not all. For some cases, you might want to have your own storage class customized with your own parameters. To demonstrate, two examples are shown. One based on using the NFS protocol, and the other using blobfuse.

Storage class using NFS protocol

In this example, the following manifest configures mounting a Blob storage container using the NFS protocol. Use it to add the tags parameter.

1. Create a file named blob-nfs-sc.yaml, and paste the following example manifest:

   apiVersion: storage.k8s.io/v1
   kind: StorageClass
   metadata:
     name: azureblob-nfs-premium
   provisioner: blob.csi.azure.com
   parameters:
     protocol: nfs
     tags: environment=Development
   volumeBindingMode: Immediate
   mountOptions:
     - nconnect=8  # only supported on linux kernel version >= 5.3
   

2. Create the storage class with the kubectl apply command:

   kubectl apply -f blob-nfs-sc.yaml
   

   The output of the command resembles the following example:

   storageclass.storage.k8s.io/blob-nfs-premium created
   

Storage class using blobfuse

In this example, the following manifest configures using blobfuse and mount a Blob storage container. Use it to update the skuName parameter.

1. Create a file named blobfuse-sc.yaml, and paste the following example manifest:

   apiVersion: storage.k8s.io/v1
   kind: StorageClass
   metadata:
     name: azureblob-fuse-premium
   provisioner: blob.csi.azure.com
   parameters:
     skuName: Standard_GRS  # available values: Standard_LRS, Premium_LRS, Standard_GRS, Standard_RAGRS
   reclaimPolicy: Delete
   volumeBindingMode: Immediate
   allowVolumeExpansion: true
   mountOptions:
     - -o allow_other
     - --file-cache-timeout-in-seconds=120
     - --use-attr-cache=true
     - --cancel-list-on-mount-seconds=10  # prevent billing charges on mounting
     - -o attr_timeout=120
     - -o entry_timeout=120
     - -o negative_timeout=120
     - --log-level=LOG_WARNING  # LOG_WARNING, LOG_INFO, LOG_DEBUG
     - --cache-size-mb=1000  # Default will be 80% of available memory, eviction will happen beyond that.
   

2. Create the storage class with the kubectl apply command:

   kubectl apply -f blobfuse-sc.yaml
   

   The output of the command resembles the following example:

   storageclass.storage.k8s.io/blob-fuse-premium created
   

Next steps

• To learn how to use CSI driver for Azure Blob storage, see [Use Azure Blob storage with CSI driver][azure-blob-storage-csi].
• To learn how to manually set up a static persistent volume, see Create and use a volume with Azure Blob storage.
• For associated best practices, see Best practices for storage and backups in AKS.