PM2 for process management in Node.js

Introduction

PM2 helps keep your Node.js apps running smoothly. It restarts apps if they crash and makes managing multiple apps easy.

You want your Node.js app to restart automatically if it crashes.

You need to run multiple Node.js apps at the same time.

You want to monitor app performance and logs easily.

You want to start your app automatically when the server boots.

You want to manage app versions and reload without downtime.

Syntax

Node.js

pm2 start <app.js> [options]
pm2 stop <app_name_or_id>
pm2 restart <app_name_or_id>
pm2 list
pm2 logs
pm2 monit

Use pm2 start to launch your app with PM2.

App can be referenced by name or ID for stop/restart commands.

Examples

Starts the app.js file with PM2.

Node.js

pm2 start app.js

Restarts the app with ID 0.

Node.js

pm2 restart 0

Stops the app named 'my-app'.

Node.js

pm2 stop my-app

Shows all running apps managed by PM2.

Node.js

pm2 list

Sample Program

This simple Node.js app creates a server that responds with a greeting. You can run it with PM2 to keep it running and restart if it crashes.

Node.js

/* app.js */
const http = require('http');
const port = 3000;

const server = http.createServer((req, res) => {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello from PM2 managed app!');
});

server.listen(port, () => {
  console.log(`Server running on port ${port}`);
});

Important Notes

PM2 can save app states and resurrect them after server reboot using pm2 save and startup scripts.

Use pm2 logs to see real-time logs of your apps.

PM2 also supports cluster mode to use multiple CPU cores for better performance.

Summary

PM2 keeps Node.js apps running and restarts them if they crash.

You can manage multiple apps easily with simple commands.

It helps monitor apps and handle server restarts smoothly.