Configuring Azure Classes for AKS

Defining Storage Class

A storage class is used to define how an Azure file share is created. A storage account is automatically created in the node resource group for use with the storage class to hold the Azure file shares.

To create a storage class you define it in an YAML file to apply it to AKS later on (using kubectl apply -f <name-of-the-yaml>.yaml):

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: my-azurestorage
  namespace: testing-volumes
provisioner: file.csi.azure.com # replace with "kubernetes.io/azure-file" if aks version is less than 1.21
allowVolumeExpansion: true
mountOptions:
  - dir_mode=0777
  - file_mode=0777
  - uid=0
  - gid=0
  - mfsymlinks
  - cache=strict
  - actimeo=30
parameters:
  skuName: Standard_LRS

You can check more about skuName in the official documentation, but basically, there are two types: Standard and Premium, and each one have different redundancy types you can choose:

• Standard_LRS - standard locally redundant storage (LRS)
• Standard_GRS - standard geo-redundant storage (GRS)
• Standard_ZRS - standard zone redundant storage (ZRS)
• Standard_RAGRS - standard read-access geo-redundant storage (RA-GRS)
• Premium_LRS - premium locally redundant storage (LRS)
• Premium_ZRS - premium zone redundant storage (ZRS)

Something to note is that Premium requires that the file shares created has to be at least of 100GB, while Standard can be as low as 1Gi

Persistent volume claim

A persistent volume claim (PVC) uses the storage class object to dynamically provision an Azure file share. In the following example we create a 1Gi PVC to use in our deployments. It’s important to know that if our Storage Class SKU is Premium, the storage request has to be at least 100Gi.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-azurefile
  namespace: testing-volumes
spec:
  accessModes:
    - ReadWriteMany
  storageClassName: my-azurestorage
  resources:
    requests:
      storage: 1Gi

Aside from the storage parameter, another important part is accessModes, in this example is configured as ReadWriteMany, that allows us to use this PVC in many pods and multiple nodes at the same time, and all of them will have Read and Write access. You can read more about accessModes in the Persistent Volumes section of the official Kubernetes documentation.

Using the persistent volume claim

You can use your PVC by referencing it on your deployment and specifying the mount point.

kind: Deployment
apiVersion: apps/v1
metadata:
  name: mywebapp
  namespace: testing-volumes
spec:
  selector:
    matchLabels:
      app: mywebapp
  template:
    metadata:
      labels:
        app: mywebapp
    spec:
      containers:
      - name: mywebapp
        image: mcr.microsoft.com/oss/nginx/nginx:1.15.5-alpine
        resources:
          requests:
            cpu: 100m
            memory: 128Mi
          limits:
            cpu: 250m
            memory: 256Mi
        volumeMounts:
        - mountPath: "/mnt/azure"
          name: volume
      volumes:
        - name: volume
          persistentVolumeClaim:
            claimName: my-azurefile