Node.js Deployment Interview Questions AWS, Docker, CI/CD, and Production

Node.js Deployment Interview Questions

Deployment knowledge is essential for full-stack developers. Here are the most common questions.

Q1: How Do You Deploy a Node.js App to Production?

Answer:

1. Provision a server (AWS EC2, DigitalOcean, etc.)
2. Install Node.js, PM2, Nginx
3. Clone the code and npm install
4. Configure .env with production secrets
5. Start with PM2 pm2 start server.js --name app
6. Configure Nginx as a reverse proxy
7. Add SSL with Let's Encrypt
8. Set up CI/CD for automated deployments

Q2: What Is PM2 and Why Use It?

Answer: PM2 is a process manager for Node.js:

• Keeps app running Survives SSH disconnection
• Auto-restart Restarts on crash
• Cluster mode Multiple instances per CPU core
• Logs Captures stdout and stderr
• Startup script Starts on system boot

pm2 start server.js --name myapp -i max  # Cluster mode
pm2 save
pm2 startup  # Start on boot

Q3: What Is the Role of Nginx in Node.js Deployment?

Answer:

1. Reverse proxy Routes port 80/443 to Node.js on 3000
2. SSL termination Handles HTTPS certificates
3. Static files Serves React/Vue build files
4. Load balancing Distributes traffic across instances
5. Gzip compression Reduces response sizes
6. Rate limiting Protects against abuse

Q4: How Do You Dockerize a Node.js App?

Answer:

# Dockerfile
FROM node:20-alpine

WORKDIR /app

COPY package*.json ./
RUN npm ci --production

COPY . .

EXPOSE 3000

CMD ["node", "src/server.js"]

# docker-compose.yml
services:
  api:
    build: .
    ports:
      - "3000:3000"
    env_file:
      - .env.production
    restart: unless-stopped

Q5: How Do You Set Up CI/CD for Node.js?

Answer:

# .github/workflows/deploy.yml
name: Deploy

on:
  push:
    branches: [main]

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: '20'
      - run: npm ci
      - run: npm test
      - name: Deploy
        uses: appleboy/ssh-action@v1
        with:
          host: ${{ secrets.EC2_HOST }}
          key: ${{ secrets.EC2_KEY }}
          script: |
            cd /app
            git pull
            npm ci
            pm2 reload myapp

Q6: How Do You Handle Zero-Downtime Deployment?

Answer:

# PM2 reload (not restart)   zero downtime
pm2 reload myapp

# In cluster mode, PM2 reloads workers one at a time
# Old workers finish requests, new workers handle new ones

With multiple instances:

# Update one at a time
pm2 reload myapp

Q7: What Are Production Best Practices?

Answer:

1. Use environment variables Never hardcode secrets
2. Set NODE_ENV=production Enables optimizations
3. Use a process manager PM2 for auto-restart
4. Enable clustering Use all CPU cores
5. Set up logging Winston + Morgan
6. Monitor PM2 monit, CloudWatch, Sentry
7. Use HTTPS Let's Encrypt + Nginx
8. Rate limit Prevent abuse
9. Backup database Regular automated backups
10. Health checks /api/health endpoint

The Takeaway

Deployment questions cover: production deployment steps (EC2, PM2, Nginx, SSL), PM2 (process manager keeps app running, auto-restart, cluster mode), Nginx role (reverse proxy, SSL, static files, load balancing, compression), Docker (Dockerfile with node:20-alpine, docker-compose), CI/CD (GitHub Actions with SSH deploy), zero-downtime (pm2 reload in cluster mode), and production best practices (env vars, NODE_ENV, logging, monitoring, HTTPS, rate limiting, backups, health checks).