Setup Nodemon to auto restart Nodejs application server

Manually restarting Node.js application is a tiring and tedious job. Nodemon is the best solution available to autorestart a nodejs app server in development mode.

Step 1

Organize the source directory src and initiate it with an app.js or index.js or server.js or any other convention you use to bootstrap a Node.js server.

Update the package.json file accordingly by adding a start script.

{
  "name": "nodemon-auto-restart",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "node src/index.js"
  },
  "keywords": [],
  "author": "Aman Mittal <amandeepmittal@live.com> (http://amandeepmittal.github.io/)",
  "license": "MIT"
}

Step 2

Add express or any other framework as dependency to bootstrap a minimal server.

Code for a minimal server:

'use strict';

const express = require('express');
const app = express();

app.use('/', (req, res) => {
  res.status(200).send('Hello World!');
});

app.listen(3000);

In first terminal window start the server:

$ npm run start
> node src/index.js

In second terminal window, request the url to test if the api is working and to see the response message:

$ curl -X GET http://localhost:3000/
Hello World!

Now if I change the response message, I have to restart the server to get the desired result:

app.use('/', (req, res) => {
  res.status(200).send('Lorem Ipsum');
});

Use Ctrl + C to stop the currently running server and restart it by using the same command before: npm run start.

Using the curl command again from terminal window we get the desired result:

curl -X GET http://localhost:3000/
Lorem Ipsum

This whole process is repetitive will slow your development of any package or application. Better solution is to use nodemon.

Step 3

Add nodemon as devDependency:

$ npm i -D nodemon

{
  "name": "nodemon-auto-restart",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "node src/index.js"
  },
  "keywords": [],
  "author": "Aman Mittal <amandeepmittal@live.com> (http://amandeepmittal.github.io/)",
  "license": "MIT",
  "dependencies": {
    "express": "4.15.3"
  },
  "devDependencies": {
    "nodemon": "1.11.0"
  }
}

Step 4

Make another script dev under npm scripts in package.json file:

{
  "scripts": {
    "start": "node src/index.js",
    "dev": "nodemon --watch src src/index.js"
  }
}

Now run $ npm run dev and request using curl command, we will see the last familiar result:

curl -X GET http://localhost:3000/
Lorem Ipsum

If I change the response message in index.js file back to Hello World, this time I don't I have to restart the server since nodemon is watching for the changes using inside the src directory, through its --watchparameter. If I use the curl command again, the result is familiar with the update:

curl -X GET http://localhost:3000/
Hello World

One can verify by observing the log messages in the terminal window where nodemon is running:

$ npm run dev

> nodemon-auto-restart@1.0.0 dev /Users/amandeepmittal/github/nodemon-auto-restart
> nodemon --watch src src/index.js

[nodemon] 1.11.0
[nodemon] to restart at any time, enter `rs`
[nodemon] watching: /Users/amandeepmittal/github/nodemon-auto-restart/src/**/*
[nodemon] starting `node src/index.js`
[nodemon] restarting due to changes...
[nodemon] starting `node src/index.js`

To stop the nodemon process, use Ctrl + C.

Full Source at this Github Repository.

Originally Published at Hackernoon.com