pm2-process

What I do

• Configure PM2 for Node.js application management
• Set up process files and clustering
• Monitor logs, metrics, and process health
• Configure auto-restart strategies and graceful shutdown
• Deploy applications with zero-downtime
• Troubleshoot process crashes and performance issues

When to use me

Use me when managing Node.js applications in production, especially when:

• Running Node.js services on servers
• Need process clustering and auto-restart
• Monitoring application health and logs
• Deploying with minimal downtime
• Managing environment-specific configurations

Common commands

• pm2 start app.js - Start application
• pm2 start ecosystem.config.js - Start with config file
• pm2 list - List all processes
• pm2 logs - View logs
• pm2 monit - Real-time monitoring
• pm2 reload all - Zero-downtime reload
• pm2 restart app - Restart process
• pm2 stop all - Stop all processes
• pm2 delete all - Remove all processes

Ecosystem configuration

module.exports = {
  apps: [{
    name: 'my-app',
    script: './dist/index.js',
    instances: 'max',
    exec_mode: 'cluster',
    env: {
      NODE_ENV: 'development',
      PORT: 3000
    },
    env_production: {
      NODE_ENV: 'production',
      PORT: 8080
    },
    error_file: './logs/error.log',
    out_file: './logs/out.log',
    log_date_format: 'YYYY-MM-DD HH:mm:ss Z',
    merge_logs: true,
    autorestart: true,
    max_memory_restart: '1G',
    watch: false
  }]
};

Clustering strategies

• Use instances: 'max' for CPU cores
• Use instances: 4 for fixed cluster size
• Enable exec_mode: 'cluster' for multi-instance
• Sticky sessions: exec_mode: cluster with load balancer

Log management

• Configure separate error and output logs
• Rotate logs with pm2 install pm2-logrotate
• Set log file size limits and retention
• Use pm2 flush to clear logs
• Stream logs to external services (e.g., ELK, Datadog)

Monitoring

• Use pm2 monit for real-time metrics
• Install pm2-plus for advanced monitoring
• Set up custom metrics with pmx
• Monitor CPU, memory, and event loop lag
• Set up alerts for process crashes

Graceful shutdown

• Handle SIGTERM signals in application code
• Close database connections before exit
• Drain HTTP connections gracefully
• Use pm2 reload instead of restart for zero downtime
• Configure kill_timeout and wait_ready

Environment management

• Separate configs per environment (env_production, env_staging)
• Load env vars from .env files
• Use pm2 startup to generate startup script
• Save process list with pm2 save

Deployment patterns

• Build before starting (npm run build && pm2 start)
• Use pm2 deploy with git-based deployment
• Implement health checks before accepting traffic
• Rollback with pm2 reload app --update-env