Manually create and use a volume with Azure Files share in Azure Kubernetes Service (AKS)

• 03/01/2019
• 4 minutes to read
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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 Files to connect using the Server Message Block (SMB) protocol. This article shows you how to manually create an Azure Files share and attach it 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. If you need an AKS cluster, see the AKS quickstart using the Azure CLI or using the Azure portal.

You also need the Azure CLI version 2.0.59 or later installed and configured. Run az --version to find the version. If you need to install or upgrade, see Install Azure CLI.

Create an Azure file share

Before you can use Azure Files as a Kubernetes volume, you must create an Azure Storage account and the file share. The following commands create a resource group named myAKSShare, a storage account, and a Files share named aksshare:

# Change these four parameters as needed for your own environment
AKS_PERS_STORAGE_ACCOUNT_NAME=mystorageaccount$RANDOM
AKS_PERS_RESOURCE_GROUP=myAKSShare
AKS_PERS_LOCATION=eastus
AKS_PERS_SHARE_NAME=aksshare

# Create a resource group
az group create --name $AKS_PERS_RESOURCE_GROUP --location $AKS_PERS_LOCATION

# Create a storage account
az storage account create -n $AKS_PERS_STORAGE_ACCOUNT_NAME -g $AKS_PERS_RESOURCE_GROUP -l $AKS_PERS_LOCATION --sku Standard_LRS

# Export the connection string as an environment variable, this is used when creating the Azure file share
export AZURE_STORAGE_CONNECTION_STRING=`az storage account show-connection-string -n $AKS_PERS_STORAGE_ACCOUNT_NAME -g $AKS_PERS_RESOURCE_GROUP -o tsv`

# Create the file share
az storage share create -n $AKS_PERS_SHARE_NAME --connection-string $AZURE_STORAGE_CONNECTION_STRING

# Get storage account key
STORAGE_KEY=$(az storage account keys list --resource-group $AKS_PERS_RESOURCE_GROUP --account-name $AKS_PERS_STORAGE_ACCOUNT_NAME --query "[0].value" -o tsv)

# Echo storage account name and key
echo Storage account name: $AKS_PERS_STORAGE_ACCOUNT_NAME
echo Storage account key: $STORAGE_KEY

Make a note of the storage account name and key shown at the end of the script output. These values are needed when you create the Kubernetes volume in one of the following steps.

Create a Kubernetes secret

Kubernetes needs credentials to access the file share created in the previous step. These credentials are stored in a Kubernetes secret, which is referenced when you create a Kubernetes pod.

Use the kubectl create secret command to create the secret. The following example creates a shared named azure-secret and populates the azurestorageaccountname and azurestorageaccountkey from the previous step. To use an existing Azure storage account, provide the account name and key.

kubectl create secret generic azure-secret --from-literal=azurestorageaccountname=$AKS_PERS_STORAGE_ACCOUNT_NAME --from-literal=azurestorageaccountkey=$STORAGE_KEY

Mount the file share as a volume

To mount the Azure Files share into your pod, configure the volume in the container spec. Create a new file named azure-files-pod.yaml with the following contents. If you changed the name of the Files share or secret name, update the shareName and secretName. If desired, update the mountPath, which is the path where the Files share is mounted in the pod. For Windows Server containers (currently in preview in AKS), specify a mountPath using the Windows path convention, such as 'D:'.

apiVersion: v1
kind: Pod
metadata:
  name: mypod
spec:
  containers:
  - image: nginx:1.15.5
    name: mypod
    resources:
      requests:
        cpu: 100m
        memory: 128Mi
      limits:
        cpu: 250m
        memory: 256Mi
    volumeMounts:
      - name: azure
        mountPath: /mnt/azure
  volumes:
  - name: azure
    azureFile:
      secretName: azure-secret
      shareName: aksshare
      readOnly: false

Use the kubectl command to create the pod.

kubectl apply -f azure-files-pod.yaml

You now have a running pod with an Azure Files share mounted at /mnt/azure. You can use kubectl describe pod mypod to verify the share is mounted successfully. The following condensed example output shows the volume mounted in the container:

Containers:
  mypod:
    Container ID:   docker://86d244cfc7c4822401e88f55fd75217d213aa9c3c6a3df169e76e8e25ed28166
    Image:          nginx:1.15.5
    Image ID:       docker-pullable://nginx@sha256:9ad0746d8f2ea6df3a17ba89eca40b48c47066dfab55a75e08e2b70fc80d929e
    State:          Running
      Started:      Sat, 02 Mar 2019 00:05:47 +0000
    Ready:          True
    Mounts:
      /mnt/azure from azure (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-z5sd7 (ro)
[...]
Volumes:
  azure:
    Type:        AzureFile (an Azure File Service mount on the host and bind mount to the pod)
    SecretName:  azure-secret
    ShareName:   aksshare
    ReadOnly:    false
  default-token-z5sd7:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-z5sd7
[...]

Mount options

Default fileMode and dirMode values differ between Kubernetes versions as described in the following table.

If using a cluster of version 1.8.5 or greater and statically creating the persistent volume object, mount options need to be specified on the PersistentVolume object.

apiVersion: v1
kind: PersistentVolume
metadata:
  name: azurefile
spec:
  capacity:
    storage: 5Gi
  accessModes:
    - ReadWriteMany
  azureFile:
    secretName: azure-secret
    shareName: azurefile
    readOnly: false
  mountOptions:
  - dir_mode=0777
  - file_mode=0777
  - uid=1000
  - gid=1000

If using a cluster of version 1.8.0 - 1.8.4, a security context can be specified with the runAsUser value set to 0. For more information on Pod security context, see Configure a Security Context.

Next steps

For associated best practices, see Best practices for storage and backups in AKS.

For more information about AKS clusters interact with Azure Files, see the Kubernetes plugin for Azure Files.