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

• 03/01/2019
• 3 minutes to read
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Container-based applications often need to access and persist data in an external data volume. If a single pod needs access to storage, you can use Azure disks to present a native volume for application use. This article shows you how to manually create an Azure disk 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 disk

When you create an Azure disk for use with AKS, you can create the disk resource in the node resource group. This approach allows the AKS cluster to access and manage the disk resource. If you instead create the disk in a separate resource group, you must grant the Azure Kubernetes Service (AKS) service principal for your cluster the Contributor role to the disk's resource group. Alternatively, you can use the system assigned managed identity for permissions instead of the service principal. For more information, see Use managed identities.

For this article, create the disk 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 name myAKSCluster in the resource group name myResourceGroup:

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

MC_myResourceGroup_myAKSCluster_eastus

Now create a disk using the az disk create command. Specify the node resource group name obtained in the previous command, and then a name for the disk resource, such as myAKSDisk. The following example creates a 20GiB disk, and outputs the ID of the disk once created. If you need to create a disk for use with Windows Server containers, add the --os-type windows parameter to correctly format the disk.

az disk create \
  --resource-group MC_myResourceGroup_myAKSCluster_eastus \
  --name myAKSDisk \
  --size-gb 20 \
  --query id --output tsv

The disk resource ID is displayed once the command has successfully completed, as shown in the following example output. This disk ID is used to mount the disk in the next step.

/subscriptions/<subscriptionID>/resourceGroups/MC_myAKSCluster_myAKSCluster_eastus/providers/Microsoft.Compute/disks/myAKSDisk

Mount disk as volume

To mount the Azure disk into your pod, configure the volume in the container spec. Create a new file named azure-disk-pod.yaml with the following contents. Update diskName with the name of the disk created in the previous step, and diskURI with the disk ID shown in output of the disk create command. If desired, update the mountPath, which is the path where the Azure disk is mounted in the pod. For Windows Server containers, 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
        azureDisk:
          kind: Managed
          diskName: myAKSDisk
          diskURI: /subscriptions/<subscriptionID>/resourceGroups/MC_myAKSCluster_myAKSCluster_eastus/providers/Microsoft.Compute/disks/myAKSDisk

Use the kubectl command to create the pod.

kubectl apply -f azure-disk-pod.yaml

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

[...]
Volumes:
  azure:
    Type:         AzureDisk (an Azure Data Disk mount on the host and bind mount to the pod)
    DiskName:     myAKSDisk
    DiskURI:      /subscriptions/<subscriptionID/resourceGroups/MC_myResourceGroupAKS_myAKSCluster_eastus/providers/Microsoft.Compute/disks/myAKSDisk
    Kind:         Managed
    FSType:       ext4
    CachingMode:  ReadWrite
    ReadOnly:     false
  default-token-z5sd7:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-z5sd7
    Optional:    false
[...]
Events:
  Type    Reason                 Age   From                               Message
  ----    ------                 ----  ----                               -------
  Normal  Scheduled              1m    default-scheduler                  Successfully assigned mypod to aks-nodepool1-79590246-0
  Normal  SuccessfulMountVolume  1m    kubelet, aks-nodepool1-79590246-0  MountVolume.SetUp succeeded for volume "default-token-z5sd7"
  Normal  SuccessfulMountVolume  41s   kubelet, aks-nodepool1-79590246-0  MountVolume.SetUp succeeded for volume "azure"
[...]

Next steps

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

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