Deploying Node.js Apps with PM2

PM2 keeps your Node apps running. Process management, clustering, and monitoring.

What is PM2?

PM2 is a production process manager for Node.js. It:

• Keeps your app running (auto-restart on crash)
• Load balances across CPU cores
• Provides monitoring and logs
• Handles deployments

Installation

npm install -g pm2

Basic Usage

# Start an app
pm2 start app.js

# With a name
pm2 start app.js --name "my-api"

# View running processes
pm2 list

# Monitor
pm2 monit

# Logs
pm2 logs
pm2 logs my-api

# Stop/restart
pm2 stop my-api
pm2 restart my-api
pm2 delete my-api

Ecosystem File

For production, use a config file:

// ecosystem.config.js
module.exports = {
  apps: [{
    name: 'api',
    script: './dist/index.js',
    instances: 'max',
    exec_mode: 'cluster',
    env: {
      NODE_ENV: 'production',
      PORT: 3000
    },
    env_development: {
      NODE_ENV: 'development',
      PORT: 3001
    }
  }]
};

# Start with ecosystem file
pm2 start ecosystem.config.js

# Start with development env
pm2 start ecosystem.config.js --env development

Cluster Mode

Spread load across all CPU cores:

{
  instances: 'max',      // Use all CPUs
  exec_mode: 'cluster'   // Enable cluster mode
}

PM2 handles load balancing automatically.

Auto-Restart on Server Boot

# Generate startup script
pm2 startup

# Save current process list
pm2 save

Now PM2 starts automatically when the server reboots.

Zero-Downtime Reload

pm2 reload my-api

In cluster mode, this restarts workers one at a time. Users never see downtime.

Monitoring

# Terminal dashboard
pm2 monit

# Or use PM2.io (free tier available)
pm2 link <public_key> <secret_key>

My Workflow

1. Build app locally 2. Push to server 3. `pm2 reload ecosystem.config.js` 4. Check `pm2 logs` for any issues

Simple, reliable, battle-tested.

When to Use Something Else

• **Docker** - If you're containerizing everything
• **Kubernetes** - At scale with orchestration needs
• **Serverless** - For event-driven functions

PM2 is perfect for traditional VPS deployments. If you're running on a DigitalOcean droplet or similar, it's the right tool.

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