Lab6-Volumes.md

Kubernetes Storage Lab

Objective

This hands-on lab will introduce students to Kubernetes storage concepts using a DigitalOcean Kubernetes (DOKS) cluster. Students will learn how to work with various Kubernetes storage methods, including emptyDir, hostPath, configMap, secret, and PVC.

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Prerequisites

• Installed and configured kubectl.
• basic understanding of Kubernetes concepts.

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Lab Outline

Module 1: Using emptyDir for Temporary Storage

emptyDir creates an ephemeral storage volume that exists as long as the Pod is running.

Step 1: Deploy a Pod with emptyDir

apiVersion: v1
kind: Pod
metadata:
  name: emptydir-demo-pod
spec:
  containers:
  - name: app
    image: nginx
    volumeMounts:
    - mountPath: "/tmp/data"
      name: temp-storage
  volumes:
  - name: temp-storage
    emptyDir: {}

Apply the Pod:

kubectl apply -f emptydir-pod.yaml

Check the volume:

kubectl exec -it emptydir-demo-pod -- ls /tmp/

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Module 2: Using hostPath to Mount a Host Directory

hostPath mounts a directory from the Kubernetes node into the Pod.

Step 2: Deploy a Pod with hostPath

apiVersion: v1
kind: Pod
metadata:
  name: hostpath-demo-pod
spec:
  containers:
  - name: app
    image: nginx
    volumeMounts:
    - mountPath: "/host-data"
      name: host-storage
  volumes:
  - name: host-storage
    hostPath:
      path: "/mnt/data"
      type: DirectoryOrCreate

Apply the Pod:

kubectl apply -f hostpath-pod.yaml

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Module 3: Using configMap for Configuration Data

Step 3: Create a ConfigMap

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  config.json: |
    {
      "key": "value"
    }

Apply the ConfigMap:

kubectl apply -f configmap.yaml

Step 4: Mount configMap in a Pod

apiVersion: v1
kind: Pod
metadata:
  name: configmap-demo-pod
spec:
  containers:
  - name: app
    image: nginx
    volumeMounts:
    - mountPath: "/etc/config"
      name: config-volume
  volumes:
  - name: config-volume
    configMap:
      name: app-config

Apply the Pod:

kubectl apply -f configmap-pod.yaml

• Assignment Validate if the ConfigMap file has been correctly mounted by validating the file contentn

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Module 4: Using secret for Sensitive Data

Step 5: Create a Secret

kubectl create secret generic my-secret --from-literal=password=supersecret

Step 6: Mount secret in a Pod

apiVersion: v1
kind: Pod
metadata:
  name: secret-demo-pod
spec:
  containers:
  - name: app
    image: nginx
    volumeMounts:
    - mountPath: "/etc/secret"
      name: secret-volume
  volumes:
  - name: secret-volume
    secret:
      secretName: my-secret

Apply the Pod:

kubectl apply -f secret-pod.yaml

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Module 5: Using PVC for Persistent Storage

Step 7: Create a Persistent Volume Claim (PVC)

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: do-pvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi
  storageClassName: do-block-storage 

Apply the PVC:

kubectl apply -f pvc.yaml

Step 8: Deploy a Pod with PVC

apiVersion: v1
kind: Pod
metadata:
  name: pvc-demo-pod
spec:
  containers:
  - name: app
    image: nginx
    volumeMounts:
    - mountPath: "/usr/share/nginx/html"
      name: storage-volume
  volumes:
  - name: storage-volume
    persistentVolumeClaim:
      claimName: do-pvc

Apply the Pod:

kubectl apply -f pvc-pod.yaml

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Module 6: Cleaning Up

To delete all resources:

kubectl delete pod emptydir-demo-pod hostpath-demo-pod configmap-demo-pod secret-demo-pod pvc-demo-pod
kubectl delete pvc do-pvc
kubectl delete secret my-secret
kubectl delete configmap app-config
kubectl delete sc do-block-storage-class

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Assignment

Task 1: Deploy a Multi-Container Pod with Shared Storage

• Create a pod with two containers.
• Use emptyDir to share data between the containers.
• One container writes a file, and the other container reads it.

Task 2: Configure a PersistentVolume and Use it in a Deployment

• Create a PersistentVolume (PV) manually.
• Create a PersistentVolumeClaim (PVC) that binds to the PV.
• Deploy an NGINX Deployment that uses the PVC for storage.

Task 3: Secure Application Configurations

• Create a ConfigMap and Secret.
• Deploy a pod that mounts the ConfigMap and Secret.
• Verify the contents inside the container.