Learn KUBERNETES with Real Code Examples

# Namespace
apiVersion: v1
kind: Namespace
metadata:
    name: my-app
    labels:
        name: my-app

---
# ConfigMap for application configuration
apiVersion: v1
kind: ConfigMap
metadata:
    name: app-config
    namespace: my-app
data:
    DATABASE_HOST: "postgres-service"
    DATABASE_PORT: "5432"
    REDIS_HOST: "redis-service"
    REDIS_PORT: "6379"

---
# Secret for sensitive data
apiVersion: v1
kind: Secret
metadata:
    name: app-secrets
    namespace: my-app
type: Opaque
data:
    DATABASE_PASSWORD: cGFzc3dvcmQxMjM=  # base64 encoded
    API_KEY: YWJjZGVmZ2hpams=

---
# Deployment
apiVersion: apps/v1
kind: Deployment
metadata:
    name: my-app-deployment
    namespace: my-app
    labels:
        app: my-app
spec:
    replicas: 3
    selector:
        matchLabels:
        app: my-app
    template:
        metadata:
        labels:
        app: my-app
        spec:
        containers:
        - name: my-app
        image: my-app:latest
        ports:
        - containerPort: 3000
        env:
        - name: DATABASE_HOST
        valueFrom:
        configMapKeyRef:
        name: app-config
        key: DATABASE_HOST
        - name: DATABASE_PASSWORD
        valueFrom:
        secretKeyRef:
        name: app-secrets
        key: DATABASE_PASSWORD
        resources:
        requests:
        memory: "256Mi"
        cpu: "200m"
        limits:
        memory: "512Mi"
        cpu: "500m"
        livenessProbe:
        httpGet:
        path: /health
        port: 3000
        initialDelaySeconds: 30
        periodSeconds: 10
        readinessProbe:
        httpGet:
        path: /ready
        port: 3000
        initialDelaySeconds: 5
        periodSeconds: 5

---
# Service
apiVersion: v1
kind: Service
metadata:
    name: my-app-service
    namespace: my-app
spec:
    selector:
        app: my-app
    ports:
    - protocol: TCP
        port: 80
        targetPort: 3000
    type: LoadBalancer

---
# Horizontal Pod Autoscaler
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
    name: my-app-hpa
    namespace: my-app
spec:
    scaleTargetRef:
        apiVersion: apps/v1
        kind: Deployment
        name: my-app-deployment
    minReplicas: 2
    maxReplicas: 10
    metrics:
    - type: Resource
        resource:
        name: cpu
        target:
        type: Utilization
        averageUtilization: 70
    - type: Resource
        resource:
        name: memory
        target:
        type: Utilization
        averageUtilization: 80

Demonstrates complete Kubernetes application deployment with configuration, secrets, services, and auto-scaling.