devops-patterns

DevOps Patterns Skill

Purpose

Deploy and operate production-grade infrastructure with modern DevOps practices.

Docker Patterns

Multi-Stage Build (Optimized)

# Stage 1: Dependencies
FROM node:20-alpine AS deps
WORKDIR /app
COPY package*.json ./
RUN npm ci --only=production && npm cache clean --force

# Stage 2: Build
FROM node:20-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build

# Stage 3: Production
FROM node:20-alpine AS runner
WORKDIR /app

# Security: non-root user
RUN addgroup --system --gid 1001 nodejs && \
    adduser --system --uid 1001 appuser

# Copy only necessary files
COPY --from=deps /app/node_modules ./node_modules
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/package.json ./

# Security hardening
USER appuser
EXPOSE 3000

# Health check
HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
  CMD wget --no-verbose --tries=1 --spider http://localhost:3000/health || exit 1

CMD ["node", "dist/index.js"]

Docker Compose for Development

version: '3.8'

services:
  api:
    build:
      context: .
      target: builder
    volumes:
      - .:/app
      - /app/node_modules
    ports:
      - "3000:3000"
    environment:
      - NODE_ENV=development
      - DATABASE_URL=postgres://user:pass@db:5432/app
      - REDIS_URL=redis://redis:6379
    depends_on:
      db:
        condition: service_healthy
      redis:
        condition: service_started

  db:
    image: postgres:16-alpine
    volumes:
      - postgres_data:/var/lib/postgresql/data
    environment:
      POSTGRES_USER: user
      POSTGRES_PASSWORD: pass
      POSTGRES_DB: app
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U user -d app"]
      interval: 5s
      timeout: 5s
      retries: 5

  redis:
    image: redis:7-alpine
    volumes:
      - redis_data:/data

volumes:
  postgres_data:
  redis_data:

Kubernetes Patterns

Production Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: api-service
  labels:
    app: api
    version: v1
spec:
  replicas: 3
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0
  selector:
    matchLabels:
      app: api
  template:
    metadata:
      labels:
        app: api
        version: v1
      annotations:
        prometheus.io/scrape: "true"
        prometheus.io/port: "3000"
    spec:
      serviceAccountName: api-service
      securityContext:
        runAsNonRoot: true
        runAsUser: 1001
      containers:
      - name: api
        image: myregistry/api:v1.2.3
        imagePullPolicy: Always
        ports:
        - containerPort: 3000
          name: http
        resources:
          requests:
            memory: "256Mi"
            cpu: "250m"
          limits:
            memory: "512Mi"
            cpu: "500m"
        env:
        - name: NODE_ENV
          value: "production"
        - name: DATABASE_URL
          valueFrom:
            secretKeyRef:
              name: api-secrets
              key: database-url
        livenessProbe:
          httpGet:
            path: /health/live
            port: http
          initialDelaySeconds: 10
          periodSeconds: 10
          failureThreshold: 3
        readinessProbe:
          httpGet:
            path: /health/ready
            port: http
          initialDelaySeconds: 5
          periodSeconds: 5
          failureThreshold: 3
        startupProbe:
          httpGet:
            path: /health/startup
            port: http
          failureThreshold: 30
          periodSeconds: 10
      affinity:
        podAntiAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
          - weight: 100
            podAffinityTerm:
              labelSelector:
                matchLabels:
                  app: api
              topologyKey: kubernetes.io/hostname
---
apiVersion: v1
kind: Service
metadata:
  name: api-service
spec:
  selector:
    app: api
  ports:
  - port: 80
    targetPort: 3000
  type: ClusterIP
---
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: api-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: api-service
  minReplicas: 3
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 70
  - type: Resource
    resource:
      name: memory
      target:
        type: Utilization
        averageUtilization: 80

Terraform Patterns

AWS EKS Module

# main.tf
terraform {
  required_version = ">= 1.5.0"

  backend "s3" {
    bucket         = "my-terraform-state"
    key            = "eks/terraform.tfstate"
    region         = "us-east-1"
    encrypt        = true
    dynamodb_table = "terraform-locks"
  }

  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
    kubernetes = {
      source  = "hashicorp/kubernetes"
      version = "~> 2.25"
    }
  }
}

module "eks" {
  source  = "terraform-aws-modules/eks/aws"
  version = "~> 20.0"

  cluster_name    = var.cluster_name
  cluster_version = "1.29"

  vpc_id     = module.vpc.vpc_id
  subnet_ids = module.vpc.private_subnets

  cluster_endpoint_public_access = true

  eks_managed_node_groups = {
    general = {
      desired_size = 3
      min_size     = 2
      max_size     = 10

      instance_types = ["t3.medium"]
      capacity_type  = "ON_DEMAND"

      labels = {
        role = "general"
      }
    }
  }

  tags = local.tags
}

# outputs.tf
output "cluster_endpoint" {
  value = module.eks.cluster_endpoint
}

output "cluster_name" {
  value = module.eks.cluster_name
}

CI/CD Pipeline

GitHub Actions

name: CI/CD Pipeline

on:
  push:
    branches: [main, develop]
  pull_request:
    branches: [main]

env:
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository }}

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v4

    - name: Setup Node.js
      uses: actions/setup-node@v4
      with:
        node-version: '20'
        cache: 'npm'

    - name: Install dependencies
      run: npm ci

    - name: Run tests
      run: npm test -- --coverage

    - name: Upload coverage
      uses: codecov/codecov-action@v4

  build:
    needs: test
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write
    outputs:
      image_tag: ${{ steps.meta.outputs.tags }}
    steps:
    - uses: actions/checkout@v4

    - name: Set up Docker Buildx
      uses: docker/setup-buildx-action@v3

    - name: Login to Container Registry
      uses: docker/login-action@v3
      with:
        registry: ${{ env.REGISTRY }}
        username: ${{ github.actor }}
        password: ${{ secrets.GITHUB_TOKEN }}

    - name: Extract metadata
      id: meta
      uses: docker/metadata-action@v5
      with:
        images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
        tags: |
          type=sha,prefix=
          type=ref,event=branch
          type=semver,pattern={{version}}

    - name: Build and push
      uses: docker/build-push-action@v5
      with:
        context: .
        push: true
        tags: ${{ steps.meta.outputs.tags }}
        cache-from: type=gha
        cache-to: type=gha,mode=max

  deploy-staging:
    needs: build
    if: github.ref == 'refs/heads/develop'
    runs-on: ubuntu-latest
    environment: staging
    steps:
    - uses: actions/checkout@v4

    - name: Deploy to Staging
      uses: azure/k8s-deploy@v4
      with:
        manifests: k8s/staging/
        images: ${{ needs.build.outputs.image_tag }}

  deploy-production:
    needs: build
    if: github.ref == 'refs/heads/main'
    runs-on: ubuntu-latest
    environment: production
    steps:
    - uses: actions/checkout@v4

    - name: Deploy to Production
      uses: azure/k8s-deploy@v4
      with:
        manifests: k8s/production/
        images: ${{ needs.build.outputs.image_tag }}
        strategy: canary
        percentage: 20

---

Unit Test Template

import { describe, it, expect } from 'vitest';
import { execSync } from 'child_process';

describe('DevOps Patterns', () => {
  describe('Dockerfile', () => {
    it('should build successfully', () => {
      expect(() => {
        execSync('docker build -t test-app .', { stdio: 'pipe' });
      }).not.toThrow();
    });

    it('should run as non-root user', () => {
      const output = execSync(
        'docker run --rm test-app whoami',
        { encoding: 'utf-8' }
      );
      expect(output.trim()).not.toBe('root');
    });

    it('should expose health endpoint', async () => {
      execSync('docker run -d --name test-container -p 3001:3000 test-app');
      await new Promise(r => setTimeout(r, 5000));

      const response = await fetch('http://localhost:3001/health');
      expect(response.ok).toBe(true);

      execSync('docker rm -f test-container');
    });
  });

  describe('Kubernetes manifests', () => {
    it('should pass kubeval validation', () => {
      expect(() => {
        execSync('kubeval k8s/*.yaml', { stdio: 'pipe' });
      }).not.toThrow();
    });

    it('should have resource limits', () => {
      const manifest = execSync('cat k8s/deployment.yaml', { encoding: 'utf-8' });
      expect(manifest).toContain('resources:');
      expect(manifest).toContain('limits:');
      expect(manifest).toContain('requests:');
    });
  });
});

---

Troubleshooting

Issue	Cause	Solution
OOMKilled pods	Memory limit too low	Increase limits, profile memory
ImagePullBackOff	Registry auth failed	Check imagePullSecrets
CrashLoopBackOff	App startup fails	Check logs, increase startupProbe
Pending pods	Insufficient resources	Add nodes or reduce requests
Slow deployments	Large images	Use multi-stage builds, slim base

---

Quality Checklist

• Docker images optimized (multi-stage, slim base)
• Non-root user in containers
• Health checks configured
• Kubernetes manifests validated
• Resource limits set
• HPA configured
• CI/CD pipeline automated
• Secrets managed securely
• Monitoring and alerting configured
• Disaster recovery plan documented