Basic Example

Target Audience: Developers who want to practice Kubernetes core resources hands-on Prerequisites: Pod, Deployment, Service concepts After reading this: You’ll be able to create and manage Pod, Deployment, Service, and ConfigMap directly

TL;DR
Create Nginx Deployment and expose via Service
Inject configuration with ConfigMap
Practice rolling updates and rollbacks

Prerequisites#

You need:

Local Kubernetes cluster (Minikube or Kind)
kubectl

# Check cluster status
kubectl cluster-info

Exercise 1: Deployment and Service#

Create Deployment#

Deploy a web server.

# nginx-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.25
        ports:
        - containerPort: 80
        resources:
          requests:
            memory: "64Mi"
            cpu: "100m"
          limits:
            memory: "128Mi"
            cpu: "200m"

# Create Deployment
kubectl apply -f nginx-deployment.yaml

# Check status
kubectl get deployment nginx
kubectl get pods -l app=nginx

Expected output:

NAME    READY   UP-TO-DATE   AVAILABLE   AGE
nginx   3/3     3            3           30s

Create Service#

Create a Service to access the Pods.

# nginx-service.yaml
apiVersion: v1
kind: Service
metadata:
  name: nginx
spec:
  type: ClusterIP
  selector:
    app: nginx
  ports:
  - port: 80
    targetPort: 80

# Create Service
kubectl apply -f nginx-service.yaml

# Check status
kubectl get service nginx
kubectl get endpoints nginx

Test Internal Access#

# Access Service from temporary Pod
kubectl run test --image=busybox:1.36 --rm -it --restart=Never \
  -- wget -qO- http://nginx

# Multiple requests will be distributed across different Pods
kubectl run test --image=busybox:1.36 --rm -it --restart=Never \
  -- sh -c 'for i in 1 2 3 4 5; do wget -qO- http://nginx 2>/dev/null | head -1; done'

External Access (NodePort)#

# Change Service type
kubectl patch service nginx -p '{"spec":{"type":"NodePort"}}'

# Access via Minikube
minikube service nginx --url

# Check assigned port
kubectl get service nginx

Exercise 2: Using ConfigMap#

Create ConfigMap#

Manage Nginx configuration with ConfigMap.

# nginx-configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: nginx-config
data:
  nginx.conf: |
    server {
        listen 80;
        server_name localhost;

        location / {
            root /usr/share/nginx/html;
            index index.html;
        }

        location /health {
            return 200 'healthy\n';
            add_header Content-Type text/plain;
        }
    }
  index.html: |
    <!DOCTYPE html>
    <html>
    <head><title>Hello Kubernetes!</title></head>
    <body>
    <h1>Hello from Kubernetes!</h1>
    <p>Pod Name: $HOSTNAME</p>
    </body>
    </html>

kubectl apply -f nginx-configmap.yaml

Mount ConfigMap in Deployment#

# nginx-deployment-with-config.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.25
        ports:
        - containerPort: 80
        volumeMounts:
        - name: config
          mountPath: /etc/nginx/conf.d/default.conf
          subPath: nginx.conf
        - name: config
          mountPath: /usr/share/nginx/html/index.html
          subPath: index.html
        resources:
          requests:
            memory: "64Mi"
            cpu: "100m"
          limits:
            memory: "128Mi"
            cpu: "200m"
      volumes:
      - name: config
        configMap:
          name: nginx-config

# Update Deployment
kubectl apply -f nginx-deployment-with-config.yaml

# Check rollout status
kubectl rollout status deployment/nginx

# Test
kubectl run test --image=busybox:1.36 --rm -it --restart=Never \
  -- wget -qO- http://nginx

Exercise 3: Rolling Updates and Rollbacks#

Update Image#

# Check current image
kubectl get deployment nginx -o jsonpath='{.spec.template.spec.containers[0].image}'

# Update image
kubectl set image deployment/nginx nginx=nginx:1.26

# Check rollout status
kubectl rollout status deployment/nginx

# Watch Pods (gradual replacement)
kubectl get pods -l app=nginx -w

Rollout History#

# Check history
kubectl rollout history deployment/nginx

# Detailed info for specific revision
kubectl rollout history deployment/nginx --revision=2

Rollback#

# Rollback to previous version
kubectl rollout undo deployment/nginx

# Rollback to specific version
kubectl rollout undo deployment/nginx --to-revision=1

# Verify
kubectl get deployment nginx -o jsonpath='{.spec.template.spec.containers[0].image}'

Exercise 4: Scaling#

Manual Scaling#

# Scale out to 5
kubectl scale deployment/nginx --replicas=5

# Verify
kubectl get pods -l app=nginx

# Scale down to 2
kubectl scale deployment/nginx --replicas=2

HPA Setup (Optional)#

# Enable Metrics Server (Minikube)
minikube addons enable metrics-server

# Create HPA
kubectl autoscale deployment nginx --cpu-percent=50 --min=2 --max=10

# Check HPA status
kubectl get hpa nginx

Exercise 5: Cleanup#

Delete Individually#

kubectl delete service nginx
kubectl delete deployment nginx
kubectl delete configmap nginx-config

Delete All at Once#

# Delete by label
kubectl delete all -l app=nginx

# Delete by YAML files
kubectl delete -f nginx-deployment.yaml -f nginx-service.yaml

Complete YAML File#

A single file containing all resources used in the exercises.

# complete-example.yaml
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: nginx-config
data:
  nginx.conf: |
    server {
        listen 80;
        location / {
            root /usr/share/nginx/html;
        }
        location /health {
            return 200 'healthy\n';
        }
    }
  index.html: |
    <h1>Hello from Kubernetes!</h1>
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.25
        ports:
        - containerPort: 80
        volumeMounts:
        - name: config
          mountPath: /etc/nginx/conf.d/default.conf
          subPath: nginx.conf
        - name: config
          mountPath: /usr/share/nginx/html/index.html
          subPath: index.html
        resources:
          requests:
            memory: "64Mi"
            cpu: "100m"
          limits:
            memory: "128Mi"
            cpu: "200m"
        livenessProbe:
          httpGet:
            path: /health
            port: 80
          initialDelaySeconds: 5
          periodSeconds: 10
        readinessProbe:
          httpGet:
            path: /health
            port: 80
          initialDelaySeconds: 5
          periodSeconds: 5
      volumes:
      - name: config
        configMap:
          name: nginx-config
---
apiVersion: v1
kind: Service
metadata:
  name: nginx
spec:
  type: ClusterIP
  selector:
    app: nginx
  ports:
  - port: 80
    targetPort: 80

# Deploy all
kubectl apply -f complete-example.yaml

# Delete all
kubectl delete -f complete-example.yaml

Next Steps#

After completing the basic example, proceed to:

Goal	Recommended Document
Deploy real app	Spring Boot Deployment
Troubleshooting	Pod Troubleshooting
Deepen concepts	Resource Management