CODEWITHSUNDEEP
azurekubernetesazure-akspersistent-volumesazure-files
vel
vel

Reputation: 1200

Pod with Azure File Share configured. Do I need PersistentVolume and PVC as well?

we have defined our YAML with

apiVersion: v1
kind: Pod
metadata:
  name: mypod
spec:
  containers:
  - image: mcr.microsoft.com/oss/nginx/nginx:1.15.5-alpine
    name: mypod
    volumeMounts:
      - name: azure
        mountPath: /mnt/azure
  volumes:
  - name: azure
    azureFile:
      secretName: azure-secret
      shareName: aksshare
      readOnly: false

and we will before the deployment create secret with kubectl command:

$AKS_PERS_STORAGE_ACCOUNT_NAME
$STORAGE_KEY

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

We already have that existing file share as Azure File Share resource and we have file stored in it.

I am confused if we need to manage and define as well yamls for kind: PersistentVolume and kind: PersistentVolumeClaim

or the above YAML is completely enough? Are PV and PVC required only if we do not have our file share already created on Azure? I've read the docs https://kubernetes.io/docs/concepts/storage/persistent-volumes/ but still feeling confused when they need to be defined and when it is OK not to use them at all during the overall deployment process.

Upvotes: 2

Views: 1543

Answers (1)

Jonas
Jonas

Reputation: 128787

Your Pod Yaml is ok.

The Kubernetes Persistent Volumes is a newer abstraction. If your application instead uses PersistentVolumeClaim it is decoupled from the type of storage you use (in your case Azure File Share) so your app can be deployed to e.g. AWS or Google Cloud or Minikube on your desktop without any changes. Your cluster need to have some support for PersistentVolumes and that part can be tied to a specific storage system.

So, to decouple your app yaml from specific infrastructure, it is better to use PersistentVolumeClaims.

Persistent Volume Example

I don't know about Azure File Share, but there is good documentation on Dynamically create and use a persistent volume with Azure Files in Azure Kubernetes Service (AKS).

Application config

Persistent Volume Claim

Your app, e.g. a Deployment or StatefulSet can have this PVC resource

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-azurefile
spec:
  accessModes:
    - ReadWriteMany
  storageClassName: my-azurefile
  resources:
    requests:
      storage: 5Gi

Then you need to create a StorageClass resource that probably is unique for each type of environment, but need to have the same name and support the same access modes. If the environment does not support dynamic volume provisioning you may to have manually create PersistentVolume resource as well.

Examples in different environments:

Pod using Persistent Volume Claim

You typically deploy apps using a Deployment or a StatefulSet but the part declaring the Pod template is similar, except that you probably want to use volumeClaimTemplate instead of PersistentVolumeClaim for StatefulSet.

See full example on Create a Pod using a PersistentVolumeClaim

apiVersion: v1
kind: Pod
metadata:
  name: task-pv-pod
spec:
  volumes:
    - name: file-share
      persistentVolumeClaim:
        claimName: my-azurefile    # this must match your name of PVC
  containers:
    - name: task-pv-container
      image: nginx
      ports:
        - containerPort: 80
          name: "http-server"
      volumeMounts:
        - mountPath: "/usr/share/nginx/html"
          name: file-share

Upvotes: 5

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