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Atlas Whoff
Atlas Whoff

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Kubernetes for Application Developers: Deployments, Ingress, Autoscaling, and CI/CD

#devops #kubernetes #docker #webdev

Kubernetes is overkill for most early-stage projects. But when you need it — high availability, zero-downtime deploys, horizontal scaling, multi-region — nothing else compares. Here's a production-ready setup without the enterprise complexity.

When You Actually Need Kubernetes

You don't need Kubernetes until you have:

  • Multiple services that need independent scaling
  • A requirement for zero-downtime deployments
  • High availability requirements (multiple replicas)
  • A team large enough to justify the operational overhead

If you're solo or a small team with one app: Vercel, Railway, or a single VPS with PM2 is the right answer. Kubernetes is a tool for scaling teams as much as scaling apps.

Minimal Production Deployment 

# k8s/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nextjs-app
  namespace: production
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nextjs-app
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0  # zero-downtime
  template:
    metadata:
      labels:
        app: nextjs-app
    spec:
      containers:
        - name: app
          image: ghcr.io/yourorg/yourapp:latest
          ports:
            - containerPort: 3000
          env:
            - name: DATABASE_URL
              valueFrom:
                secretKeyRef:
                  name: app-secrets
                  key: database-url
          resources:
            requests:
              memory: '256Mi'
              cpu: '100m'
            limits:
              memory: '512Mi'
              cpu: '500m'
          readinessProbe:
            httpGet:
              path: /api/health
              port: 3000
            initialDelaySeconds: 10
            periodSeconds: 5
          livenessProbe:
            httpGet:
              path: /api/health
              port: 3000
            initialDelaySeconds: 30
            periodSeconds: 10
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Service and Ingress 

# k8s/service.yaml
apiVersion: v1
kind: Service
metadata:
  name: nextjs-app
spec:
  selector:
    app: nextjs-app
  ports:
    - port: 80
      targetPort: 3000
---
# k8s/ingress.yaml
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: nextjs-app
  annotations:
    cert-manager.io/cluster-issuer: letsencrypt-prod
    nginx.ingress.kubernetes.io/proxy-body-size: '50m'
spec:
  tls:
    - hosts: [myapp.com]
      secretName: myapp-tls
  rules:
    - host: myapp.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: nextjs-app
                port:
                  number: 80
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Secrets Management 

# Create secrets from .env file
kubectl create secret generic app-secrets \
  --from-literal=database-url='postgresql://...' \
  --from-literal=stripe-secret='sk_live_...' \
  --namespace=production

# Or from a file
kubectl create secret generic app-secrets \
  --from-env-file=.env.production \
  --namespace=production
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Horizontal Pod Autoscaler 

# k8s/hpa.yaml
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: nextjs-app
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: nextjs-app
  minReplicas: 2
  maxReplicas: 10
  metrics:
    - type: Resource
      resource:
        name: cpu
        target:
          type: Utilization
          averageUtilization: 70
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CI/CD Deploy 

# .github/workflows/deploy.yml
- name: Build and push image
  uses: docker/build-push-action@v5
  with:
    push: true
    tags: ghcr.io/${{ github.repository }}:${{ github.sha }}

- name: Deploy to Kubernetes
  run: |
    kubectl set image deployment/nextjs-app \
      app=ghcr.io/${{ github.repository }}:${{ github.sha }} \
      --namespace=production
    kubectl rollout status deployment/nextjs-app --namespace=production
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The rollout status command waits for the deployment to complete and fails the CI job if pods don't become ready.

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