Create and use a static 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 create an Azure Blob storage container or use an existing one and attach it to a pod in AKS.

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

• 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.

When you create an Azure Blob storage resource for use with AKS, you can create the resource in the node resource group. This approach allows the AKS cluster to access and manage the blob storage resource. If instead you create the blob storage resource in a separate resource group, you must grant the Azure Kubernetes Service managed identity for your cluster the Contributor role to the blob storage resource group.

For this article, create the container in the node resource group. First, get the resource group name with the az aks show command and add the --query nodeResourceGroup query parameter. The following example gets the node resource group for the AKS cluster named myAKSCluster in the resource group named myResourceGroup:

az aks show --resource-group myResourceGroup --name myAKSCluster --query nodeResourceGroup -o tsv

The output of the command resembles the following example:

MC_myResourceGroup_myAKSCluster_chinaeast2

Next, create a container for storing blobs following the steps in the Manage blob storage to authorize access and then create the container.

Mounting Blob storage using the NFS v3 protocol doesn't authenticate using an account key. Your AKS cluster needs to reside in the same or peered virtual network as the agent node. The only way to secure the data in your storage account is by using a virtual network and other network security settings. For more information on how to set up NFS access to your storage account, see Mount Blob Storage by using the Network File System (NFS) 3.0 protocol.

The following example demonstrates how to mount a Blob storage container as a persistent volume using the NFS protocol.

1. Create a file named pv-blob-nfs.yaml and copy in the following YAML. Under storageClass, update resourceGroup, storageAccount, and containerName.

   apiVersion: v1
   kind: PersistentVolume
   metadata:
     name: pv-blob
   spec:
     capacity:
       storage: 10Gi
     accessModes:
       - ReadWriteMany
     persistentVolumeReclaimPolicy: Retain  # If set as "Delete" container would be removed after pvc deletion
     storageClassName: azureblob-nfs-premium
     csi:
       driver: blob.csi.azure.com
       readOnly: false
       # make sure this volumeid is unique in the cluster
       # `#` is not allowed in self defined volumeHandle
       volumeHandle: unique-volumeid
       volumeAttributes:
         resourceGroup: resourceGroupName
         storageAccount: storageAccountName
         containerName: containerName
         protocol: nfs
   

2. Run the following command to create the persistent volume using the kubectl create command referencing the YAML file created earlier:

   kubectl create -f pv-blob-nfs.yaml
   

3. Create a pvc-blob-nfs.yaml file with a PersistentVolume. For example:

   kind: PersistentVolumeClaim
   apiVersion: v1
   metadata:
     name: pvc-blob
   spec:
     accessModes:
       - ReadWriteMany
     resources:
       requests:
         storage: 10Gi
     volumeName: pv-blob
     storageClassName: azureblob-nfs-premium
   

4. Run the following command to create the persistent volume claim using the kubectl create command referencing the YAML file created earlier:

   kubectl create -f pvc-blob-nfs.yaml
   

Kubernetes needs credentials to access the Blob storage container created earlier, which is either an Azure access key or SAS tokens. These credentials are stored in a Kubernetes secret, which is referenced when you create a Kubernetes pod.

1. Use the kubectl create secret command to create the secret. You can authenticate using a Kubernetes secret or shared access signature (SAS) tokens.

   • Secret
   • SAS tokens

   The following example creates a Secret object named azure-secret and populates the azurestorageaccountname and azurestorageaccountkey. You need to provide the account name and key from an existing Azure storage account.

   kubectl create secret generic azure-secret --from-literal azurestorageaccountname=NAME --from-literal azurestorageaccountkey="KEY" --type=Opaque
   

2. Create a pv-blobfuse.yaml file. Under volumeAttributes, update containerName. Under nodeStateSecretRef, update name with the name of the Secret object created earlier. For example:

   apiVersion: v1
   kind: PersistentVolume
   metadata:
     name: pv-blob
   spec:
     capacity:
       storage: 10Gi
     accessModes:
       - ReadWriteMany
     persistentVolumeReclaimPolicy: Retain  # If set as "Delete" container would be removed after pvc deletion
     storageClassName: azureblob-fuse-premium
     mountOptions:
       - -o allow_other
       - --file-cache-timeout-in-seconds=120
     csi:
       driver: blob.csi.azure.com
       readOnly: false
       # make sure this volumeid is unique in the cluster
       # `#` is not allowed in self defined volumeHandle
       volumeHandle: unique-volumeid
       volumeAttributes:
         containerName: containerName
       nodeStageSecretRef:
         name: azure-secret
         namespace: default
   

3. Run the following command to create the persistent volume using the kubectl create command referencing the YAML file created earlier:

   kubectl create -f pv-blobfuse.yaml
   

4. Create a pvc-blobfuse.yaml file with a PersistentVolume. For example:

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: pvc-blob
   spec:
     accessModes:
       - ReadWriteMany
     resources:
       requests:
         storage: 10Gi
     volumeName: pv-blob
     storageClassName: azureblob-fuse-premium
   

5. Run the following command to create the persistent volume claim using the kubectl create command referencing the YAML file created earlier:

   kubectl create -f pvc-blobfuse.yaml
   

The following YAML creates a pod that uses the persistent volume or persistent volume claim named pvc-blob created earlier, to mount the Azure Blob storage at the `/mnt/blob' path.

1. Create a file named nginx-pod-blob.yaml, and copy in the following YAML. Make sure that the claimName matches the PVC created in the previous step when creating a persistent volume for NFS or Blobfuse.

   kind: Pod
   apiVersion: v1
   metadata:
     name: nginx-blob
   spec:
     nodeSelector:
       "kubernetes.io/os": linux
     containers:
       - image: mcr.azk8s.cn/oss/nginx/nginx:1.17.3-alpine
         name: nginx-blob
         volumeMounts:
           - name: blob01
             mountPath: "/mnt/blob"
     volumes:
       - name: blob01
         persistentVolumeClaim:
           claimName: pvc-blob
   

2. Run the following command to create the pod and mount the PVC using the kubectl create command referencing the YAML file created earlier:

   kubectl create -f nginx-pod-blob.yaml
   

3. Run the following command to create an interactive shell session with the pod to verify the Blob storage mounted:

   kubectl exec -it nginx-blob -- df -h
   

   The output from the command resembles the following example:

   Filesystem      Size  Used Avail Use% Mounted on
   ...
   blobfuse         14G   41M   13G   1% /mnt/blob
   ...
   

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