Kubernetes Storage Deep Dive Lab

This lab covers:

• Volumes (emptyDir)
• Persistent Volumes (PV)
• Persistent Volume Claims (PVC)
• StorageClass with dynamic provisioning

---

1. Prerequisites

• Kubernetes cluster (Minikube or any cloud provider)
• kubectl installed and configured

For local testing, start Minikube:

minikube start

---

2. Volumes Lab (EmptyDir)

Concept:

• emptyDir is a simple volume that exists as long as the pod runs.
• Data is deleted once the pod is removed.

YAML: pod-emptydir.yaml

apiVersion: v1
kind: Pod
metadata:
  name: emptydir-demo
spec:
  containers:
    - name: app-container
      image: busybox
      command: ["/bin/sh", "-c", "echo Hello > /data/hello.txt && sleep 3600"]
      volumeMounts:
        - mountPath: /data
          name: data-volume
  volumes:
    - name: data-volume
      emptyDir: {}

Execution Steps

kubectl apply -f pod-emptydir.yaml
kubectl get pods
kubectl exec -it emptydir-demo -- cat /data/hello.txt

Expected Output:

Hello

Cleanup

kubectl delete pod emptydir-demo

---

3. Persistent Volumes (PV) and Persistent Volume Claims (PVC)

Concept:

• PV: A storage resource in the cluster.
• PVC: A user’s request for storage.

We will:

1. Create a 1Gi PV
2. Create a 1Gi PVC
3. Bind a pod to the PVC

YAML: pv-pvc.yaml

---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-demo
spec:
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: /tmp/pv-data
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-demo
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi

Execution Steps

kubectl apply -f pv-pvc.yaml
kubectl get pv
kubectl get pvc

• PV status → Bound
• PVC status → Bound

---

4. Pod Using PVC

YAML: pod-pvc.yaml

apiVersion: v1
kind: Pod
metadata:
  name: pvc-pod
spec:
  containers:
    - name: app
      image: busybox
      command: ["/bin/sh", "-c", "echo PV Test > /data/test.txt && sleep 3600"]
      volumeMounts:
        - mountPath: /data
          name: pvc-storage
  volumes:
    - name: pvc-storage
      persistentVolumeClaim:
        claimName: pvc-demo

Execution Steps

kubectl apply -f pod-pvc.yaml
kubectl get pods
kubectl exec -it pvc-pod -- cat /data/test.txt

Expected Output:

PV Test

Cleanup

kubectl delete pod pvc-pod
kubectl delete pvc pvc-demo
kubectl delete pv pv-demo

---

5. StorageClass with Dynamic Provisioning

Concept:

• StorageClass allows dynamic PV provisioning without creating PV manually.
• PVCs referencing the SC are automatically fulfilled.

For Minikube: Use standard StorageClass (already available).
For learning, we will create a local StorageClass with no-provisioner.

---

YAML: storageclass.yaml

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: sc-demo
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer

---

PVC Using StorageClass: pvc-sc.yaml

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-sc-demo
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 500Mi
  storageClassName: sc-demo

---

Pod Using SC PVC: pod-sc.yaml

apiVersion: v1
kind: Pod
metadata:
  name: sc-pod
spec:
  containers:
    - name: app
      image: busybox
      command: ["/bin/sh", "-c", "echo SC Test > /data/sc.txt && sleep 3600"]
      volumeMounts:
        - mountPath: /data
          name: sc-storage
  volumes:
    - name: sc-storage
      persistentVolumeClaim:
        claimName: pvc-sc-demo

---

Execution Steps

kubectl apply -f storageclass.yaml
kubectl apply -f pvc-sc.yaml
kubectl get pvc
kubectl apply -f pod-sc.yaml
kubectl get pods
kubectl exec -it sc-pod -- cat /data/sc.txt

Expected Output:

SC Test

---

Cleanup

kubectl delete pod sc-pod
kubectl delete pvc pvc-sc-demo
kubectl delete sc sc-demo

---

6. Verify Cleanup

kubectl get all
kubectl get pv
kubectl get pvc
kubectl get sc

---

Lab Completed!
You have now practiced:

• Volumes (emptyDir)
• Persistent Volumes (PV)
• Persistent Volume Claims (PVC)
• StorageClass with dynamic provisioning