Storage classes for dynamic provisioning in Kubernetes - Commands & Configuration

Introduction

When you need storage for your applications in Kubernetes, you can create it automatically using storage classes. This saves you from manually setting up storage every time. Storage classes tell Kubernetes how to create storage on demand.

When you want your app to get storage automatically without manual setup.

When you need different types of storage like fast SSD or cheaper HDD for different apps.

When you want to manage storage policies like encryption or replication easily.

When you want to avoid errors from manually creating storage volumes.

When you want to scale storage dynamically as your app grows.

Config File - storageclass.yaml

storageclass.yaml

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast-storage
provisioner: kubernetes.io/aws-ebs
parameters:
  type: gp2
  fsType: ext4
reclaimPolicy: Delete
volumeBindingMode: Immediate

This file defines a StorageClass named fast-storage. It uses the AWS Elastic Block Store (EBS) provisioner to create gp2 type volumes formatted with ext4 filesystem. The reclaimPolicy: Delete means storage is deleted when no longer used. volumeBindingMode: Immediate means volumes are created right when requested.

Commands

This command creates the StorageClass in your Kubernetes cluster so it can be used for dynamic storage provisioning.

Terminal

kubectl apply -f storageclass.yaml

Expected Output

storageclass.storage.k8s.io/fast-storage created

This command lists all StorageClasses available in the cluster to verify that your new StorageClass was created.

Terminal

kubectl get storageclass

Expected Output

NAME           PROVISIONER             RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE

fast-storage   kubernetes.io/aws-ebs   Delete         Immediate           false                  10s

This command creates a PersistentVolumeClaim that requests storage using the StorageClass named fast-storage. Kubernetes will dynamically create the storage volume.

Terminal

kubectl apply -f pvc.yaml

Expected Output

persistentvolumeclaim/my-pvc created

This command checks the status of the PersistentVolumeClaim to see if the storage has been successfully provisioned and bound.

Terminal

kubectl get pvc my-pvc

Expected Output

NAME     STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE

my-pvc   Bound    pvc-12345678-90ab-cdef-1234-567890abcdef   5Gi        RWO            fast-storage   15s

Key Concept

If you remember nothing else from this pattern, remember: StorageClasses let Kubernetes create storage automatically when your app asks for it.

Common Mistakes

Not specifying the correct provisioner in the StorageClass.

Kubernetes won't know how to create the storage and the PVC will stay pending.

Use the provisioner that matches your cloud or storage system, like kubernetes.io/aws-ebs for AWS.

Creating a PersistentVolumeClaim without specifying the StorageClass name.

Kubernetes may use the default StorageClass or fail if none is set, causing unexpected storage types or errors.

Always specify the storageClassName field in your PVC to use the desired StorageClass.

Deleting the StorageClass while PVCs are still using it.

Existing volumes may become unmanaged or cause errors when deleted unexpectedly.

Only delete StorageClasses when no PVCs are using them or after cleaning up PVCs.

Summary

Create a StorageClass YAML file to define how storage is dynamically provisioned.

Apply the StorageClass to the cluster using kubectl apply.

Create a PersistentVolumeClaim that requests storage from the StorageClass.

Check the PVC status to confirm storage was provisioned and bound.