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Create and use a volume with Azure Blob storage in Azure Kubernetes Service (AKS)

  • Article

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:

  • Work with a dynamic persistent volume (PV) by installing the Container Storage Interface (CSI) driver and dynamically creating an Azure Blob storage container to attach to a pod.
  • Work with a static PV by creating an Azure Blob storage container, or use an existing one and attach it to a pod.

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

Before you begin

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

  • To support an Azure DataLake Gen2 storage account when using blobfuse mount, you'll need to do the following:

    • To create an ADLS account using the driver in dynamic provisioning, specify isHnsEnabled: "true" in the storage class parameters.
    • To enable blobfuse access to an ADLS account in static provisioning, specify the mount option --use-adls=true in the persistent volume.
    • If you are going to enable a storage account with Hierarchical Namespace, existing persistent volumes should be remounted with --use-adls=true mount option.

  • About blobfuse cache

    • By default, the blobfuse cache is located in the /mnt directory. If the VM SKU provides a temporary disk, the /mnt directory is mounted on the temporary disk. However, if the VM SKU does not provide a temporary disk, the /mnt directory is mounted on the OS disk, you could set --tmp-path= mount option to specify a different cache directory

Dynamically provision a volume

This section provides guidance for cluster administrators who want to provision one or more persistent volumes that include details of Blob storage for use by a workload. A persistent volume claim (PVC) uses the storage class object to dynamically provision an Azure Blob storage container.

Storage class parameters for dynamic PersistentVolumes

The following table includes parameters you can use to define a custom storage class for your PersistentVolumeClaim.

Name Description Example Mandatory Default value
skuName Specify an Azure storage account type (alias: storageAccountType). Standard_LRS, Premium_LRS, Standard_GRS, Standard_RAGRS No Standard_LRS
location Specify an Azure location. eastus No If empty, driver will use the same location name as current cluster.
resourceGroup Specify an Azure resource group name. myResourceGroup No If empty, driver will use the same resource group name as current cluster.
storageAccount Specify an Azure storage account name. storageAccountName - No for blobfuse mount
- Yes for NFSv3 mount.		 - For blobfuse mount: if empty, driver finds a suitable storage account that matches skuName in the same resource group. If a storage account name is provided, storage account must exist.
- For NFSv3 mount, storage account name must be provided.
networkEndpointType Specify network endpoint type for the storage account created by driver. If privateEndpoint is specified, a private endpoint is created for the storage account. For other cases, a service endpoint will be created for NFS protocol.1 privateEndpoint No For an AKS cluster, add the AKS cluster name to the Contributor role in the resource group hosting the VNET.
protocol Specify blobfuse mount or NFSv3 mount. fuse, nfs No fuse
containerName Specify the existing container (directory) name. container No If empty, driver creates a new container name, starting with pvc-fuse for blobfuse or pvc-nfs for NFS v3.
containerNamePrefix Specify Azure storage directory prefix created by driver. my Can only contain lowercase letters, numbers, hyphens, and length should be fewer than 21 characters. No
server Specify Azure storage account domain name. Existing storage account DNS domain name, for example <storage-account>.privatelink.blob.core.windows.net. No If empty, driver uses default <storage-account>.blob.core.windows.net or other sovereign cloud storage account DNS domain name.
allowBlobPublicAccess Allow or disallow public access to all blobs or containers for storage account created by driver. true,false No false
storageEndpointSuffix Specify Azure storage endpoint suffix. core.windows.net No If empty, driver will use default storage endpoint suffix according to cloud environment.
tags Tags would be created in new storage account. Tag format: 'foo=aaa,bar=bbb' No ""
matchTags Match tags when driver tries to find a suitable storage account. true,false No false
--- Following parameters are only for blobfuse --- --- ---
subscriptionID Specify Azure subscription ID where blob storage directory will be created. Azure subscription ID No If not empty, resourceGroup must be provided.
storeAccountKey Specify store account key to Kubernetes secret.

Note:
false means driver uses kubelet identity to get account key.		 true,false No true
secretName Specify secret name to store account key. No
secretNamespace Specify the namespace of secret to store account key. default,kube-system, etc. No pvc namespace
isHnsEnabled Enable Hierarchical namespace for Azure Data Lake storage account. true,false No false
--- Following parameters are only for NFS protocol --- --- ---
mountPermissions Specify mounted folder permissions. The default is 0777. If set to 0, driver won't perform chmod after mount. 0777 No

1 If the storage account is created by the driver, then you only need to specify networkEndpointType: privateEndpoint parameter in storage class. The CSI driver creates the private endpoint together with the account. If you bring your own storage account, then you need to create the private endpoint for the storage account.

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
spec:
  accessModes:
  - ReadWriteMany
  storageClassName: azureblob-nfs-premium
  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.microsoft.com/oss/nginx/nginx:1.17.3-alpine
    resources:
      requests:
        cpu: 100m
        memory: 128Mi
      limits:
        cpu: 250m
        memory: 256Mi
    volumeMounts:
    - mountPath: "/mnt/blob"
      name: volume
      readOnly: false
  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
allowVolumeExpansion: true
mountOptions:
  - nconnect=4

  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 mounts 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

Statically provision a volume

This section provides guidance for cluster administrators who want to create one or more persistent volumes that include details of Blob storage for use by a workload.

Static provisioning parameters for PersistentVolume

The following table includes parameters you can use to define a PersistentVolume.

Name Description Example Mandatory Default value
volumeHandle Specify a value the driver can use to uniquely identify the storage blob container in the cluster. A recommended way to produce a unique value is to combine the globally unique storage account name and container name: {account-name}_{container-name}.
Note: The #, / character are reserved for internal use and can't be used in a volume handle.		 Yes
volumeAttributes.resourceGroup Specify Azure resource group name. myResourceGroup No If empty, driver uses the same resource group name as current cluster.
volumeAttributes.storageAccount Specify an existing Azure storage account name. storageAccountName Yes
volumeAttributes.containerName Specify existing container name. container Yes
volumeAttributes.protocol Specify blobfuse mount or NFS v3 mount. fuse, nfs No fuse
--- Following parameters are only for blobfuse --- --- ---
volumeAttributes.secretName Secret name that stores storage account name and key (only applies for SMB). No
volumeAttributes.secretNamespace Specify namespace of secret to store account key. default No Pvc namespace
nodeStageSecretRef.name Specify secret name that stores one of the following:
azurestorageaccountkey
azurestorageaccountsastoken
msisecret
azurestoragespnclientsecret.		 No Existing Kubernetes secret name
nodeStageSecretRef.namespace Specify the namespace of secret. Kubernetes namespace Yes
--- Following parameters are only for NFS protocol --- --- ---
volumeAttributes.mountPermissions Specify mounted folder permissions. 0777 No
--- Following parameters are only for NFS VNet setting --- --- ---
vnetResourceGroup Specify VNet resource group hosting virtual network. myResourceGroup No If empty, driver uses the vnetResourceGroup value specified in the Azure cloud config file.
vnetName Specify the virtual network name. aksVNet No If empty, driver uses the vnetName value specified in the Azure cloud config file.
subnetName Specify the existing subnet name of the agent node. aksSubnet No If empty, driver uses the subnetName value in Azure cloud config file.
--- Following parameters are only for feature: blobfuse
Managed Identity and Service Principal Name authentication		 --- --- ---
volumeAttributes.AzureStorageAuthType Specify the authentication type. Key, SAS, MSI, SPN No Key
volumeAttributes.AzureStorageIdentityClientID Specify the Identity Client ID. No
volumeAttributes.AzureStorageIdentityObjectID Specify the Identity Object ID. No
volumeAttributes.AzureStorageIdentityResourceID Specify the Identity Resource ID. No
volumeAttributes.MSIEndpoint Specify the MSI endpoint. No
volumeAttributes.AzureStorageSPNClientID Specify the Azure Service Principal Name (SPN) Client ID. No
volumeAttributes.AzureStorageSPNTenantID Specify the Azure SPN Tenant ID. No
volumeAttributes.AzureStorageAADEndpoint Specify the Microsoft Entra endpoint. No
--- Following parameters are only for feature: blobfuse read account key or SAS token from key vault --- --- ---
volumeAttributes.keyVaultURL Specify Azure Key Vault DNS name. {vault-name}.vault.azure.net No
volumeAttributes.keyVaultSecretName Specify Azure Key Vault secret name. Existing Azure Key Vault secret name. No
volumeAttributes.keyVaultSecretVersion Azure Key Vault secret version. Existing version No If empty, driver uses current version.

Create a Blob storage container

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.

For this article, create the container in the node resource group. First, get the resource group name with the [az aks show][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_eastus

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

Mount volume

In this section, you mount the persistent volume using the NFS protocol or Blobfuse.

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.

    Note

    volumeHandle value should be a unique volumeID for every identical storage blob container in the cluster. The character # and / are reserved for internal use and cannot be used.

    apiVersion: v1
kind: PersistentVolume
metadata:
  annotations:
    pv.kubernetes.io/provisioned-by: blob.csi.azure.com
  name: pv-blob
spec:
  capacity:
    storage: 1Pi
  accessModes:
    - ReadWriteMany
  persistentVolumeReclaimPolicy: Retain  # If set as "Delete" container would be removed after pvc deletion
  storageClassName: azureblob-nfs-premium
  mountOptions:
    - nconnect=4
  csi:
    driver: blob.csi.azure.com
    # make sure volumeid is unique for every identical storage blob container in the cluster
    # character `#` and `/` are reserved for internal use and cannot be used in volumehandle
    volumeHandle: account-name_container-name
    volumeAttributes:
      resourceGroup: resourceGroupName
      storageAccount: storageAccountName
      containerName: containerName
      protocol: nfs

    Note

    While the Kubernetes API capacity attribute is mandatory, this value isn't used by the Azure Blob storage CSI driver because you can flexibly write data until you reach your storage account's capacity limit. The value of the capacity attribute is used only for size matching between PersistentVolumes and PersistenVolumeClaims. We recommend using a fictitious high value. The pod sees a mounted volume with a fictitious size of 5 Petabytes.

  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 PersistentVolumeClaim. 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

Use the persistent volume

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.microsoft.com/oss/nginx/nginx:1.17.3-alpine
      name: nginx-blob
      volumeMounts:
        - name: blob01
          mountPath: "/mnt/blob"
          readOnly: false
  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
...

Next steps