Use a custom StorageClass with your workloads

GKE on Azure automatically deploys Azure Disk CSI Driver and Azure File CSI Driver .

The Azure Disk CSI Driver and Azure File CSI Driver versions are tied to an GKE on Azure Kubernetes version. The driver version is typically the latest available when a GKE version is released. When the cluster is upgraded, the drivers update automatically.

Use a custom StorageClass

You can create additional StorageClasses for volumes or use Container Storage Interface (CSI) Drivers.

1. Choose if you are using an Azure disk volume or another CSI driver.

   Azure Disk Volume

   You can create your own custom StorageClass that specifies an Azure Disk volume type, file system type, and other parameters. You can find additional StorageClass parameters on the GKE on Azure Azure Disk CSI Driver GitHub page .

   To configure a custom StorageClass, copy the following YAML manifest into a file named my-custom-class.yaml .

     apiVersion 
    : 
     
    storage.k8s.io/v1 
    kind 
    : 
     
    StorageClass 
    metadata 
    : 
     
    name 
    : 
     
     CLASS_NAME 
    
    provisioner 
    : 
     
    disk.csi.azure.com 
    volumeBindingMode 
    : 
     
    WaitForFirstConsumer 
    allowVolumeExpansion 
    : 
     
    true 
    
   

   Replace CLASS_NAME with the name of your new StorageClass.

   For example, the following YAML creates a new StorageClass that provisions volumes in a specific storage account and applies a tag of group=dev to each new volume.

     apiVersion 
    : 
     
    storage.k8s.io/v1 
    kind 
    : 
     
    StorageClass 
    metadata 
    : 
     
    name 
    : 
     
     my-custom-class 
    
    provisioner 
    : 
     
    disk.csi.azure.com 
    volumeBindingMode 
    : 
     
    WaitForFirstConsumer 
    allowVolumeExpansion 
    : 
     
    true 
    parameters 
    : 
     
    storageAccount 
    : 
     
     my-storage-account 
    
     
    tags 
    : 
     
     group=dev 
    
    
   

   CSI Driver

   You can specify a different CSI driver in the provisioner field.

   To create a StorageClass with another CSI driver, you can use the example YAML below.

     apiVersion 
    : 
     
    storage.k8s.io/v1 
    kind 
    : 
     
    StorageClass 
    metadata 
    : 
     
    name 
    : 
     
     CLASS_NAME 
    
    provisioner 
    : 
     
     CSI_DRIVER_NAME 
    
    volumeBindingMode 
    : 
     
    WaitForFirstConsumer 
    parameters 
    : 
     
     ... 
    
    
   

   Replace the following values:

   • CLASS_NAME : the name of the StorageClass (for example, my-custom-class ).
   • CSI_DRIVER_NAME : the name of the CSI driver (for example, csi.example.com ).

   Next, configure subfields under parameters according to your CSI driver's documentation.

2. Apply the YAML to your cluster.

    kubectl  
   apply  
   -f  
   my-custom-class.yaml 
   

3. Create a PersistentVolumeClaim with a custom StorageClass.

   After you create a custom StorageClass, you can specify it in a PVC. The following example creates a PVC named my-pvc that references the StorageClass my-custom-class .

     apiVersion 
    : 
     
    v1 
    kind 
    : 
     
    PersistentVolumeClaim 
    metadata 
    : 
     
    name 
    : 
     
    my-pvc 
    spec 
    : 
     
    accessModes 
    : 
     
    - 
     
    ReadWriteOnce 
     
    resources 
    : 
     
    requests 
    : 
     
    storage 
    : 
     
    30Gi 
     
    storageclassName 
    : 
     
    my-custom-class 
    
   

Set the default StorageClass

GKE on Azure uses a default StorageClass called standard-rwo that provisions standard SSD Azure disks with LRS . You can change the default to another StorageClass.

To change the default StorageClass:

1. Update the is-default-class annotation for the standard-rwo StorageClass with kubectl patch .

    kubectl  
   patch  
   storageclass  
   standard-rwo  
   -p  
    \ 
     
    '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"false"}}}' 
    
   

2. Create a new StorageClass that has the annotation storageclass.kubernetes.io/is-default-class: true .

   The following example StorageClass uses the disk.csi.azure.com driver. To install another storage driver, see Installing a CSI driver .

   Copy the following YAML into a file named my-custom-class.yaml .

     apiVersion 
    : 
     
    storage.k8s.io/v1 
    kind 
    : 
     
    StorageClass 
    metadata 
    : 
     
    name 
    : 
     
     CLASS_NAME 
    
     
    annotations 
    : 
     
    storageclass.kubernetes.io/is-default-class 
    : 
     
    true 
    provisioner 
    : 
     
    disk.csi.azure.com 
    volumeBindingMode 
    : 
     
    WaitForFirstConsumer 
    parameters 
    : 
     
    skuName 
    : 
     
     VOLUME_TYPE 
    
    
   

   Replace the following:

   • CLASS_NAME : the name of your new StorageClass.
   • VOLUME_TYPE : the Azure Disk volume type that the StorageClass creates.

   For example, the following YAML creates a new default StorageClass that provisions Premium SSD Azure Disk volumes.

     apiVersion 
    : 
     
    storage.k8s.io/v1 
    kind 
    : 
     
    StorageClass 
    metadata 
    : 
     
    name 
    : 
     
    my-custom-default-class 
     
    annotations 
    : 
     
    storageclass.kubernetes.io/is-default-class 
    : 
     
    "true" 
    provisioner 
    : 
     
    disk.csi.azure.com 
    volumeBindingMode 
    : 
     
    WaitForFirstConsumer 
    parameters 
    : 
     
    skuName 
    : 
     
    Premium_LRS 
    
   

3. Apply the new custom class to your cluster.

    kubectl  
   apply  
   -f  
   my-custom-class.yaml 
   

After applying this manifest, GKE on Azure uses the my-custom-default-class StorageClass for new storage requests.

Reference the StorageClass in a StatefulSet

To use your new StorageClass, you can reference it in a StatefulSet's volumeClaimTemplates .

When you reference a StorageClass in a StatefulSet's volumeClaimTemplates specification, Kubernetes provides stable storage using PersistentVolumes (PVs). Kubernetes calls the provisioner defined in the StorageClass to create a new storage volume. After the volume is provisioned, Kubernetes automatically creates a PV.

The following StatefulSet references the my-custom-class StorageClass and provisions a 1 gibibyte volume:

  apiVersion 
 : 
  
 apps/v1 
 kind 
 : 
  
 StatefulSet 
 metadata 
 : 
  
 name 
 : 
  
 web 
 spec 
 : 
  
 selector 
 : 
  
 matchLabels 
 : 
  
 app 
 : 
  
 nginx 
  
 template 
 : 
  
 metadata 
 : 
  
 labels 
 : 
  
 app 
 : 
  
 nginx 
  
 spec 
 : 
  
 containers 
 : 
  
 - 
  
 name 
 : 
  
 nginx 
  
 image 
 : 
  
 registry.k8s.io/nginx-slim:0.8 
  
 volumeMounts 
 : 
  
 - 
  
 name 
 : 
  
 www 
  
 mountPath 
 : 
  
 /usr/share/nginx/html 
  
 volumeClaimTemplates 
 : 
  
 # This is the specification in which you reference the StorageClass 
  
 - 
  
 metadata 
 : 
  
 name 
 : 
  
 www 
  
 spec 
 : 
  
 accessModes 
 : 
  
 [ 
  
 "ReadWriteOnce" 
  
 ] 
  
 resources 
 : 
  
 requests 
 : 
  
 storage 
 : 
  
 1Gi 
  
 storageClassName 
 : 
  
 my-custom-class 
  
 # This field references the existing StorageClass 
 

What's next

• Read the documentation for the Azure Disk CSI driver or the Azure File CSI driver .

• Learn about Persistent volumes in GKE .

• Install Storage drivers on your GKE on Azure cluster.

• Deploy your first workload with the Quickstart .