Deploying a Node.js Application with PM2

What Is PM2?

PM2 is a production process manager for Node.js applications. It keeps your app running, handles restarts on failure, provides logging, and supports clustering for multi-core utilization.

Installation

npm install -g pm2

Basic Usage

# Start an application
pm2 start app.js --name "my-api"

# Start with environment variables
pm2 start app.js --name "my-api" --env production

# View running processes
pm2 list

# Monitor in real-time
pm2 monit

Cluster Mode

Run multiple instances across CPU cores:

# Use all available cores
pm2 start app.js -i max --name "my-api"

# Use specific number of instances
pm2 start app.js -i 4 --name "my-api"

Ecosystem File

Create ecosystem.config.js:

module.exports = {
  apps: [{
    name: "my-api",
    script: "app.js",
    instances: "max",
    exec_mode: "cluster",
    env: {
      NODE_ENV: "production",
      PORT: 3000
    },
    max_memory_restart: "500M",
    log_date_format: "YYYY-MM-DD HH:mm:ss",
    error_file: "./logs/error.log",
    out_file: "./logs/output.log"
  }]
};

pm2 start ecosystem.config.js

Auto-Start on Boot

pm2 startup systemd
# Run the generated command
pm2 save

Common Commands

pm2 restart my-api     # Restart
pm2 reload my-api      # Zero-downtime reload
pm2 stop my-api        # Stop
pm2 delete my-api      # Remove from PM2
pm2 logs my-api        # View logs
pm2 logs --lines 100   # Last 100 lines