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About Yatin Batra

Yatin Batra
An experience full-stack engineer well versed with Core Java, Spring/Springboot, MVC, Security, AOP, Frontend (Angular & React), and cloud technologies (such as AWS, GCP, Jenkins, Docker, K8).

Local Authentication Using Passport in Node.js

Hello. This tutorial will explain authentication in the Node.js applications through the passport module.

1. Introduction

Passport.js is an authentication middleware designed for Nodejs. passport-local uses the passport strategy for authenticating with a username and password. The module helps to authenticate using a username and password in the nodejs applications. If you are interested in reading further about this module take a look at this link.

1.1 Setting up Node.js

To set up Node.js on windows you will need to download the installer from this link. Click on the installer (also include the NPM package manager) for your platform and run the installer to start with the Node.js setup wizard. Follow the wizard steps and click on Finish when it is done. If everything goes well you can navigate to the command prompt to verify if the installation was successful as shown in Fig. 1.

Passport in Node.js - npm installation
Fig. 1: Verifying node and npm installation

2. Local Authentication Using Passport in Node.js

To set up the application, we will need to navigate to a path where our project will reside. For programming stuff, I am using Visual Studio Code as my preferred IDE. You’re free to choose the IDE of your choice.

2.1 Setting up the implementation

Let us write the different files which will be required for practical learning.

2.1.1 Setting up dependencies

Navigate to the project directory and run npm init -y to create a package.json file. This file holds the metadata relevant to the project and is used for managing the project dependencies, script, version, etc. Add the following code to the file wherein we will specify the required dependencies.

package.json

{
  "name": "passport-app",
  "version": "1.0.0",
  "description": "",
  "main": "server.js",
  "scripts": {
    "start": "nodemon server.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "bcrypt": "^5.0.1",
    "ejs": "^3.1.6",
    "express": "^4.17.1",
    "express-flash": "0.0.2",
    "express-session": "^1.17.2",
    "method-override": "^3.0.0",
    "passport": "^0.4.1",
    "passport-local": "^1.0.0"
  },
  "devDependencies": {
    "dotenv": "^10.0.0",
    "nodemon": "^2.0.12"
  }
}

To download the dependencies navigate to the directory path containing the file and use the npm install command. If everything goes well the dependencies will be loaded inside the node_modules folder and you are good to go with the further steps.

2.1.2 View – Creating welcome screen

In the root folder create a folder named views and add the following content to the index.ejs. This screen will be responsible to show the welcome page after successful authentication.

index.ejs

<h1>Hi <%= name %></h1>
<form action="/logout?_method=DELETE" method="POST">
  <button type="submit">Sign Out</button>
</form>

2.1.3 View – Creating login screen

In the root folder create a folder named views and add the following content to the login.ejs. This screen will be responsible for the login.

index.ejs

<h1>Login</h1>
<% if (messages.error) { %> <%= messages.error %> <% } %>
<form action="/login" method="POST">
  <div>
    <label for="email">Email</label>
    <input type="email" id="email" name="email" required />
  </div>
  <div>
    <label for="password">Password</label>
    <input type="password" id="password" name="password" required />
  </div>
  <button type="submit">Login</button>
</form>
<a href="/register">Sign up</a>

2.1.4 View – Creating registration screen

In the root folder create a folder named views and add the following content to the login.ejs. This screen will be responsible for the registration of new users.

index.ejs

<h1>Register</h1>
<form action="/register" method="POST">
  <div>
    <label for="name">Name</label>
    <input type="text" id="name" name="name" required />
  </div>
  <div>
    <label for="email">Email</label>
    <input type="email" id="email" name="email" required />
  </div>
  <div>
    <label for="password">Password</label>
    <input type="password" id="password" name="password" required />
  </div>
  <button type="submit">Register</button>
</form>
<a href="/login">Login</a>

2.1.5 Creating passport configuration

In the root folder add the following content to the configuration file. The file will be responsible to configure the strategy using a username and password. The strategy will also require a callback that will accept the credentials and calls a done(…) method to provide the user details.

passport-config.js

// adding passport related configuration

const LocalStrategy = require("passport-local").Strategy;
const bcrypt = require("bcrypt");

function initialize(passport, getUserByEmail, getUserById) {
  const authenticateUser = async (email, password, done) => {
    const user = getUserByEmail(email);
    if (user == null) {
      return done(null, false, { message: "User not found" });
    }

    try {
      if (await bcrypt.compare(password, user.password)) {
        return done(null, user);
      } else {
        return done(null, false, { message: "Invalid credentials" });
      }
    } catch (e) {
      return done(e);
    }
  };

  passport.use(new LocalStrategy({ usernameField: "email" }, authenticateUser));
  passport.serializeUser((user, done) => done(null, user.id));
  passport.deserializeUser((id, done) => {
    return done(null, getUserById(id));
  });
}

module.exports = initialize;

2.1.6 Creating controller

In the root folder add the following content to the index file. The file will be responsible to initialize the imports, routes, and specify the passport configuration to authenticate the requests. Remember to create a .env file at the same location and specify the sensitive information such as session-secret, application port number, etc.

server.js

if (process.env.NODE_ENV !== "production") {
  require("dotenv").config();
}

// imports
const express = require("express");
const app = express();
const bcrypt = require("bcrypt");
const passport = require("passport");
const flash = require("express-flash");
const session = require("express-session");
const methodOverride = require("method-override");

// todo - add external db support
const users = [];

// configuring and initializing passport
const initializePassport = require("./passport-config");
initializePassport(
  passport,
  (email) => users.find((user) => user.email === email),
  (id) => users.find((user) => user.id === id)
);

app.set("view-engine", "ejs");
app.use(express.urlencoded({ extended: false }));
app.use(flash());
app.use(
  session({
    secret: process.env.SESSION_SECRET || "8unto0n4oc7903zm",
    resave: false,
    saveUninitialized: false,
  })
);
app.use(passport.initialize());
app.use(passport.session());
app.use(methodOverride("_method"));

// routes

// welcome page
// display greetings message for the user and logout button
app.get("/", checkAuthenticated, (req, res) => {
  res.render("index.ejs", { name: req.user.name });
});

// login page
app.get("/login", checkNotAuthenticated, (req, res) => {
  res.render("login.ejs");
});

app.post(
  "/login",
  checkNotAuthenticated,
  passport.authenticate("local", {
    successRedirect: "/",
    failureRedirect: "/login",
    failureFlash: true,
  })
);

// new user sign-up page
app.get("/register", checkNotAuthenticated, (req, res) => {
  res.render("register.ejs");
});

app.post("/register", checkNotAuthenticated, async (req, res) => {
  try {
    const hashedPassword = await bcrypt.hash(req.body.password, 10);
    users.push({
      id: "_" + Math.random().toString(36).slice(2),
      name: req.body.name,
      email: req.body.email,
      password: hashedPassword,
    });

    res.redirect("/login");
  } catch (e) {
    // console.log(e);
    res.redirect("/redirect");
  }

  // check if the user is successfully added to array
  // console.log(users);
});

// logout of the application
app.delete("/logout", (req, res) => {
  req.logOut();
  res.redirect("/login");
});

// util methods

// only authenticated user should enter index page
function checkAuthenticated(req, res, next) {
  if (req.isAuthenticated()) {
    return next();
  } else {
    res.redirect("/login");
  }
}

// unauthenticated user should not enter index page
function checkNotAuthenticated(req, res, next) {
  if (req.isAuthenticated()) {
    return res.redirect("/");
  }
  next();
}

// start server
const port = process.env.APPLICATION_PORT || 6001;
app.listen(port, () => {
  console.log("Server listening at http://localhost:%s", port);
});

3. Run the Application

To run the application navigate to the project directory and enter the following command as shown in Fig. 2. If everything goes well the application will be started successfully on a port number read from the .env file or 6001.

Passport in Node.js - starting the app
Fig. 2: Starting the application

4. Demo

Once the application is started successfully navigate to the following url to show the login screen. You can click on the signup button for creating a new user and play around with the application after that. In this tutorial, I have also added some of the basic validations like user not found and invalid credentials.

Endpoint

http://localhost:YOUR_PORT_NUMBER

That is all for this tutorial and I hope the article served you with whatever you were looking for. Happy Learning and do not forget to share!

5. Summary

In this tutorial, we learned about the passport module and how to create a simple login application with the help of passport-local dependency. You can download the source code and the postman collection from the Downloads section.

6. Download the Project

This was a tutorial to implement local authentication using a passport module in a nodejs application.

Download
You can download the full source code of this example here: Local Authentication Using Passport in Node.js
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