Node.js Backend Development Bootcamp · Lesson

Process Management with PM2

Learn to use PM2 for managing, monitoring, and scaling Node.js applications in production environments.

Process Management with PM2 is a free Node.js Backend Development Bootcamp lesson on CoddyKit — lesson 3 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Node.js Backend Development Bootcamp learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

What is PM2?

Welcome to process management with PM2! PM2 stands for Process Manager 2, and it's a powerful tool for Node.js applications.

In production, you need your application to run reliably, restart if it crashes, and utilize server resources efficiently. PM2 handles all of this.

Keep Alive: Automatically restarts your app if it crashes.
Monitoring: Provides insights into your app's performance.
Scaling: Easily run multiple instances of your app for better performance.

Installing PM2 Globally

Getting started with PM2 is straightforward. You install it globally using npm, so it's available as a command-line tool on your system.

Open your terminal and run the following command:

npm install -g pm2

This command installs the PM2 CLI (Command Line Interface) globally, allowing you to use pm2 commands from any directory.

Starting Your First App

Once installed, you can start any Node.js application with a simple command. PM2 will keep it running in the background, even if your terminal closes!

First, here's a basic Node.js server:

const http = require('http');

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

const PORT = 3000;
server.listen(PORT, () => {
  console.log(`Server running on port ${PORT}`);
});

Launching with PM2

To start the server from the previous scene (let's say it's saved as app.js) with PM2, you'd run:

pm2 start app.js --name my-first-app

The --name flag gives your process a friendly identifier. PM2 will then list your running application, showing its status, uptime, and other details.

If your app crashes, PM2 will automatically restart it, ensuring high availability!

Monitoring Your Processes

PM2 offers excellent tools to monitor your running applications. You can quickly see a list of all managed processes and their statuses.

pm2 list: Shows a table of all your PM2-managed processes, including their ID, name, status, CPU usage, memory usage, and uptime.
pm2 monit: Provides a dashboard-like view in your terminal, displaying real-time CPU, memory, and log data for all your applications. It's great for quick health checks.

Stopping & Restarting Apps

Managing the lifecycle of your applications is simple with PM2. You can stop, restart, or delete processes using their name or ID.

pm2 stop my-first-app: Stops the application named 'my-first-app'.
pm2 restart my-first-app: Restarts the application. Useful after code changes.
pm2 delete my-first-app: Stops the application and removes it from PM2's process list.
pm2 stop all: Stops all running applications managed by PM2.

These commands give you full control over your deployed Node.js services.

Using a Configuration File

For more complex setups or managing multiple applications, PM2 allows you to use a configuration file (e.g., ecosystem.config.js). This file defines your applications, environment variables, and other settings.

Here's a simple app for demonstration:

const http = require('http');
const port = process.env.PORT || 3001;

http.createServer((req, res) => {
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end(`Hello from config app on port ${port} (PID: ${process.pid})!\n`);
}).listen(port, () => {
  console.log(`Config demo server running on port ${port}`);
});

Ecosystem Config Example

Now, let's define an ecosystem.config.js to manage this app:

module.exports = {
  apps : [{
    name: "my-config-app",
    script: "app-config-demo.js",
    instances: 1,
    exec_mode: "fork",
    env: {
      NODE_ENV: "development",
      PORT: 3001
    },
    env_production: {
      NODE_ENV: "production",
      PORT: 80
    }
  }]
};

To start this app using the config file, you'd run: pm2 start ecosystem.config.js. This is great for version control and consistent deployments.

Scaling with Clustering Mode

Node.js is single-threaded, but modern servers have multiple CPU cores. PM2's clustering mode allows you to run multiple instances of your app, distributing the load across all available cores.

Here's a simple app that shows its process ID:

const http = require('http');
const process = require('process');

const server = http.createServer((req, res) => {
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end(`Hello from instance ${process.pid}!\n`);
});

const PORT = 3002;
server.listen(PORT, () => {
  console.log(`Cluster server ${process.pid} running on port ${PORT}`);
});

Running in Cluster Mode

To start the app from the previous scene (e.g., app-cluster.js) in cluster mode, you can use:

pm2 start app-cluster.js -i max

The -i max flag tells PM2 to launch as many instances as your CPU has cores. PM2 will then act as a load balancer, distributing incoming requests among these instances. This significantly improves performance and resilience.

PM2 Quick Check

You've learned how to manage, monitor, and scale your Node.js applications with PM2. Let's test your understanding!

Recap & Next Steps

Great job! You've successfully learned the fundamentals of process management with PM2.

PM2 is an essential tool for deploying and maintaining Node.js applications in production, offering features like automatic restarts, monitoring, and easy scaling through clustering.

Keep exploring PM2's documentation for more advanced features, such as log management, startup scripts, and custom metrics. Happy deploying!

Frequently asked questions

Is the “Process Management with PM2” lesson free?

Yes — the full text of “Process Management with PM2” is free to read here on the web, and the Node.js Backend Development Bootcamp course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Node.js Backend Development Bootcamp course, upgrade to CoddyKit PRO.

What will I learn in “Process Management with PM2”?

Learn to use PM2 for managing, monitoring, and scaling Node.js applications in production environments. You practise Node.js Backend Development Bootcamp with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Node.js Backend Development Bootcamp?

No prior experience is required. Node.js Backend Development Bootcamp on CoddyKit is structured for beginners through advanced learners; this is — lesson 3 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Process Management with PM2” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Node.js Backend Development Bootcamp lesson?

Yes. Every Node.js Backend Development Bootcamp lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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