Kubernetes StorageClass Explained and Lab Tutorial

1. Introduction to StorageClass

1.1 What is StorageClass

StorageClass is a resource object in Kubernetes used to describe storage types and policies. It provides administrators with a way to describe "classes" of storage they offer. Different classes may map to different quality-of-service levels, backup policies, or arbitrary policies set by the cluster admin.

1.2 Core Functions of StorageClass

Dynamic Volume Provisioning: Automatically creates PVs, no need for manual pre-provisioning
Storage Abstraction: Provides users with a unified storage access interface, hiding backend details
Policy Management: Defines reclaim policies, mount options, etc.
Multi-backend Support: Supports different storage systems (NFS, cloud storage, local storage, etc.)

1.3 Relationship with PV/PVC

User creates PVC → specifies StorageClass → Provisioner dynamically creates PV → PVC binds PV → Pod uses storage

2. Core Components of StorageClass

2.1 Provisioner

The Provisioner is responsible for dynamically creating PVs. Common types include:

Built-in Provisioners:
- kubernetes.io/aws-ebs (AWS EBS)
- kubernetes.io/gce-pd (Google Cloud Persistent Disk)
- kubernetes.io/azure-disk (Azure Disk)
External Provisioners:
- k8s-sigs.io/nfs-subdir-external-provisioner (NFS)
- csi.driver.name (CSI driver)

2.2 Parameters

Defines specific configuration parameters for storage. Supported parameters vary by provisioner.

2.3 ReclaimPolicy

Delete: Default. PV and backend storage are deleted when PVC is deleted
Retain: PV and data are retained, manual cleanup required

2.4 VolumeBindingMode

Immediate: Bind immediately (default)
WaitForFirstConsumer: Wait until the first consumer (Pod) is scheduled before binding

3. NFS StorageClass Lab Environment Setup

3.1 Prerequisites

This lab requires:

Kubernetes cluster (v1.18+)
NFS server (IP: 10.128.0.5)
NFS shared directory: /nfs/share

3.2 NFS Server Configuration

On the NFS server, run:

bash

dnf install nfs-utils rpcbind

mkdir -p /nfs/share
chown nobody:nobody /nfs/share
chmod 755 /nfs/share

echo "/nfs/share *(rw,sync,no_subtree_check,no_root_squash)" >> /etc/exports

systemctl enable --now rpcbind
systemctl enable --now nfs-server

exportfs -ra

showmount -e localhost

3.3 Kubernetes Node Configuration

On all Kubernetes nodes, install the NFS client:

bash

dnf install nfs-utils

apt-get update && apt-get install -y nfs-common

showmount -e 10.128.0.5

4. Deploy NFS External Provisioner

4.1 Create Namespace

bash

kubectl create namespace nfs-storageclass

4.2 Deploy RBAC Permissions

Create serviceAccount.yaml:

yaml

apiVersion: v1
kind: ServiceAccount
metadata:
  name: nfs-client-provisioner
  namespace: nfs-storageclass
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: nfs-client-provisioner-runner
rules:
  - apiGroups: [""]
    resources: ["nodes"]
    verbs: ["get", "list", "watch"]
  - apiGroups: [""]
    resources: ["persistentvolumes"]
    verbs: ["get", "list", "watch", "create", "delete"]
  - apiGroups: [""]
    resources: ["persistentvolumeclaims"]
    verbs: ["get", "list", "watch", "update"]
  - apiGroups: ["storage.k8s.io"]
    resources: ["storageclasses"]
    verbs: ["get", "list", "watch"]
  - apiGroups: [""]
    resources: ["events"]
    verbs: ["create", "update", "patch"]
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: run-nfs-client-provisioner
subjects:
  - kind: ServiceAccount
    name: nfs-client-provisioner
    namespace: nfs-storageclass
roleRef:
  kind: ClusterRole
  name: nfs-client-provisioner-runner
  apiGroup: rbac.authorization.k8s.io
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: leader-locking-nfs-client-provisioner
  namespace: nfs-storageclass
rules:
  - apiGroups: [""]
    resources: ["endpoints"]
    verbs: ["get", "list", "watch", "create", "update", "patch"]
---
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: leader-locking-nfs-client-provisioner
  namespace: nfs-storageclass
subjects:
  - kind: ServiceAccount
    name: nfs-client-provisioner
    namespace: nfs-storageclass
roleRef:
  kind: Role
  name: leader-locking-nfs-client-provisioner
  apiGroup: rbac.authorization.k8s.io

4.3 Deploy NFS Provisioner

Create nfs-client.yaml:

yaml

kind: Deployment
apiVersion: apps/v1
metadata:
  name: nfs-client-provisioner
  namespace: nfs-storageclass
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nfs-client-provisioner
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: nfs-client-provisioner
    spec:
      serviceAccountName: nfs-client-provisioner
      containers:
        - name: nfs-client-provisioner
          image: k8s.dockerproxy.com/sig-storage/nfs-subdir-external-provisioner:v4.0.2
          volumeMounts:
            - name: nfs-client-root
              mountPath: /persistentvolumes
          env:
            - name: PROVISIONER_NAME
              value: k8s-sigs.io/nfs-subdir-external-provisioner
            - name: NFS_SERVER
              value: 10.140.0.8  # NFS server IP
            - name: NFS_PATH
              value: /nfs/share  # NFS share path
      volumes:
        - name: nfs-client-root
          nfs:
            server: 10.140.0.8
            path: /nfs/share

4.4 Create StorageClass

Create storageClass.yaml:

yaml

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: nfs-client
  namespace: nfs-storageclass
provisioner: k8s-sigs.io/nfs-subdir-external-provisioner
parameters:
  pathPattern: ${.PVC.namespace}/${.PVC.name}
  onDelete: delete

Parameter Explanation:

pathPattern: Defines the directory path pattern created on the NFS server
- ${.PVC.namespace}: PVC’s namespace
- ${.PVC.name}: PVC’s name
onDelete: Behavior when PVC is deleted
- delete: Delete the corresponding NFS directory
- retain: Retain the NFS directory

5. Lab Operations

5.1 Deploy All Components

bash

kubectl apply -f serviceAccount.yaml

kubectl apply -f nfs-client.yaml

kubectl apply -f storageClass.yaml

kubectl get pods -n nfs-storageclass
kubectl get storageclass

5.2 Create Test PVC and Pod

Create pod.yaml:

yaml

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: test-claim
spec:
  accessModes:
    - ReadWriteMany  # Multi-node read/write
  resources:
    requests:
      storage: 1Mi   # Request 1MB storage
  storageClassName: nfs-client  # Specify StorageClass
---
kind: Pod
apiVersion: v1
metadata:
  name: test-pod
spec:
  containers:
    - name: test-pod
      image: wangyanglinux/myapp:v1.0  # Nginx image
      volumeMounts:
        - name: nfs-pvc
          mountPath: "/usr/share/nginx/html"  # Mount to Nginx web root
  restartPolicy: "Never"
  volumes:
    - name: nfs-pvc
      persistentVolumeClaim:
        claimName: test-claim

5.3 Run the Test

bash

kubectl apply -f pod.yaml

kubectl get pvc test-claim

kubectl get pv

kubectl get pods test-pod -o wide

ls -la /nfs/share/default/test-claim/

5.4 Verify Storage Functionality

bash

POD_IP=$(kubectl get pod test-pod -o jsonpath='{.status.podIP}')

curl $POD_IP

kubectl exec -it test-pod -- /bin/bash
echo "Hello from NFS StorageClass!" > /usr/share/nginx/html/index.html
exit

curl $POD_IP

cat /nfs/share/default/test-claim/index.html

6. Advanced Features

6.1 Set Default StorageClass

bash

kubectl patch storageclass nfs-client -p '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"true"}}}'

kubectl get storageclass

6.2 Volume Binding Mode

yaml

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: nfs-client-wait
provisioner: k8s-sigs.io/nfs-subdir-external-provisioner
volumeBindingMode: WaitForFirstConsumer  # Wait for first consumer
parameters:
  pathPattern: ${.PVC.namespace}/${.PVC.name}
  onDelete: delete

6.3 Mount Options

yaml

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: nfs-client-custom
provisioner: k8s-sigs.io/nfs-subdir-external-provisioner
mountOptions:
  - hard          # Hard mount
  - nfsvers=4     # Use NFSv4
  - timeo=600     # Timeout
parameters:
  pathPattern: ${.PVC.namespace}/${.PVC.name}
  onDelete: retain  # Retain data

7. Troubleshooting and Maintenance

7.1 Common Issue Diagnosis

bash

kubectl logs -n nfs-storageclass deployment/nfs-client-provisioner

kubectl describe pvc test-claim

kubectl describe storageclass nfs-client

kubectl exec -it test-pod -- df -h

journalctl -u nfs-server -f

7.2 Performance Optimization Suggestions

NFS Mount Option Optimization:

yaml

mountOptions:
  - vers=4.1
  - rsize=1048576
  - wsize=1048576
  - hard
  - timeo=600
  - retrans=2

Network Optimization:
- Use gigabit or 10-gigabit networks
- Configure dedicated NFS network
- Adjust MTU size
Storage Optimization:
- Use SSD storage
- Configure RAID
- Regularly back up important data

7.3 Clean Up Resources

bash

kubectl delete -f pod.yaml

kubectl delete -f storageClass.yaml

kubectl delete -f nfs-client.yaml
kubectl delete -f serviceAccount.yaml

kubectl delete namespace nfs-storageclass

8. Lab Summary

Through this lab, we learned:

Basic concepts of StorageClass: Understanding its role and core components
Dynamic volume provisioning: How to automatically create PVs via StorageClass
NFS integration: How to integrate NFS storage into Kubernetes
Practical application: Validated the StorageClass workflow through a complete lab

Key Points

StorageClass simplifies storage management and enables dynamic provisioning
The Provisioner is the core of StorageClass, responsible for actual storage creation
Different storage backends require different provisioners and parameter configs
Proper storage policy configuration is critical for production

Production Advice

Security: Configure proper RBAC and network policies
High Availability: Deploy multiple Provisioner replicas, configure storage HA
Monitoring: Set up comprehensive storage monitoring and alerting
Backup: Develop data backup and recovery strategies
Testing: Regularly perform disaster recovery tests

技术博客 | Go & Kubernetes & Linux

1. Introduction to StorageClass ​

1.1 What is StorageClass ​

1.2 Core Functions of StorageClass ​

1.3 Relationship with PV/PVC ​

2. Core Components of StorageClass ​

2.1 Provisioner ​

2.2 Parameters ​

2.3 ReclaimPolicy ​

2.4 VolumeBindingMode ​

3. NFS StorageClass Lab Environment Setup ​

3.1 Prerequisites ​

3.2 NFS Server Configuration ​

3.3 Kubernetes Node Configuration ​

4. Deploy NFS External Provisioner ​

4.1 Create Namespace ​

4.2 Deploy RBAC Permissions ​

4.3 Deploy NFS Provisioner ​

4.4 Create StorageClass ​

5. Lab Operations ​

5.1 Deploy All Components ​

5.2 Create Test PVC and Pod ​

5.3 Run the Test ​

5.4 Verify Storage Functionality ​

6. Advanced Features ​

6.1 Set Default StorageClass ​

6.2 Volume Binding Mode ​

6.3 Mount Options ​

7. Troubleshooting and Maintenance ​

7.1 Common Issue Diagnosis ​

7.2 Performance Optimization Suggestions ​

7.3 Clean Up Resources ​

8. Lab Summary ​

Key Points ​

Production Advice ​

1. Introduction to StorageClass

1.1 What is StorageClass

1.2 Core Functions of StorageClass

1.3 Relationship with PV/PVC

2. Core Components of StorageClass

2.1 Provisioner

2.2 Parameters

2.3 ReclaimPolicy

2.4 VolumeBindingMode

3. NFS StorageClass Lab Environment Setup

3.1 Prerequisites

3.2 NFS Server Configuration

3.3 Kubernetes Node Configuration

4. Deploy NFS External Provisioner

4.1 Create Namespace

4.2 Deploy RBAC Permissions

4.3 Deploy NFS Provisioner

4.4 Create StorageClass

5. Lab Operations

5.1 Deploy All Components

5.2 Create Test PVC and Pod

5.3 Run the Test

5.4 Verify Storage Functionality

6. Advanced Features

6.1 Set Default StorageClass

6.2 Volume Binding Mode

6.3 Mount Options

7. Troubleshooting and Maintenance

7.1 Common Issue Diagnosis

7.2 Performance Optimization Suggestions

7.3 Clean Up Resources

8. Lab Summary

Key Points

Production Advice