DevOps Essentials — Docker, CI/CD, and Deploying Next.js Apps

# Dockerfile
FROM node:20-alpine AS base
 
# Install dependencies
FROM base AS deps
WORKDIR /app
COPY package*.json ./
RUN npm ci
 
# Build
FROM base AS builder
WORKDIR /app
COPY --from=deps /app/node_modules ./node_modules
COPY . .
RUN npm run build
 
# Production image
FROM base AS runner
WORKDIR /app
ENV NODE_ENV=production
 
COPY --from=builder /app/.next/standalone ./
COPY --from=builder /app/.next/static ./.next/static
COPY --from=builder /app/public ./public
 
EXPOSE 3000
CMD ["node", "server.js"]

# docker-compose.yml
services:
  app:
    build: .
    ports:
      - "3000:3000"
    environment:
      DATABASE_URL: postgresql://user:pass@db:5432/mydb
    depends_on:
      - db
 
  db:
    image: postgres:16-alpine
    environment:
      POSTGRES_DB: mydb
      POSTGRES_USER: user
      POSTGRES_PASSWORD: pass
    volumes:
      - postgres_data:/var/lib/postgresql/data
 
volumes:
  postgres_data:

# .github/workflows/deploy.yml
name: Deploy
 
on:
  push:
    branches: [main]
 
jobs:
  deploy:
    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 & Build
        run: |
          npm ci
          npm run build
 
      - name: Run Tests
        run: npm test
 
      - name: Deploy to Vercel
        uses: amondnet/vercel-action@v25
        with:
          vercel-token: ${{ secrets.VERCEL_TOKEN }}
          vercel-org-id: ${{ secrets.ORG_ID }}
          vercel-project-id: ${{ secrets.PROJECT_ID }}
          vercel-args: '--prod'

# .env.example (commit this)
DATABASE_URL=postgresql://user:pass@localhost:5432/mydb
NEXTAUTH_SECRET=your-secret-here
OPENAI_API_KEY=sk-...
 
# .env.local (never commit)
DATABASE_URL=postgresql://real-user:real-pass@prod-host:5432/prod-db

// app/api/health/route.ts
export async function GET() {
  return Response.json({ status: 'ok', timestamp: new Date().toISOString() })
}