Effortless Authentication: Implementing Auth0 in Your Next.js Application

Authentication is a critical aspect of any modern web application. With cybercrime on the rise, securing your application against unauthorized access has become increasingly important. In this tutorial, we will learn how to integrate Auth0, a popular authentication and authorization solution, with a Next.js application. This will allow us to authenticate users and protect our web application against security threats.

Requirements

Before we begin, make sure you have the following prerequisites:

  • Basic knowledge of JavaScript and React
  • Node.js installed on your machine (version 14.x or higher)
  • A code editor of your choice (VSCode, Sublime Text, etc.)

Create a Next.js Application

First, let us start by creating a new Next.js application using the following commands in your terminal:

npm install -g create-next-app
create-next-app my-auth-app
cd my-auth-app
npm run dev

The last command will start the development server, and you should be able to view your Next.js application by navigating to http://localhost:3000 in your browser.

Setting Up Auth0

Next, we need to set up Auth0 to handle the authentication process for our application. If you do not have an Auth0 account, visit their signup page and create one for free.

Follow these steps to configure your Auth0 application:

  1. Log in to your Auth0 account and navigate to the "Applications" tab.
  2. Click "Create Application" and provide a name for your application, such as "My Auth App". Select "Single Page Web Applications" as the application type and click "Create".
  3. In the "Settings" tab of your newly created application, scroll down to "Allowed Callback URLs" and add http://localhost:3000/api/callback.
  4. Scroll down to "Allowed Logout URLs" and add http://localhost:3000/.
  5. Save the changes by clicking the "Save Changes" button at the bottom.

Once your Auth0 application is configured, take note of your "Domain" and "Client ID" found in the "Settings" tab. We will use these values later in our Next.js application.

Integrating Auth0 in Your Next.js Application

Now that we have Auth0 set up, let's implement authentication in our Next.js application. First, we need to install the required dependencies:

npm install @auth0/auth0-react

Next, create a new file called _app.js in the pages directory and add the following contents:

import React from 'react';
import { Auth0Provider } from '@auth0/auth0-react';

function MyApp({ Component, pageProps }) {
  return (
    <Auth0Provider
      domain="{YOUR_AUTH0_DOMAIN}"
      clientId="{YOUR_AUTH0_CLIENT_ID}"
      redirectUri={typeof window !== 'undefined' ? window.location.origin + "/api/callback" : undefined}
    >
      <Component {...pageProps} />
    </Auth0Provider>
  );
}

export default MyApp;

Replace {YOUR_AUTH0_DOMAIN} and {YOUR_AUTH0_CLIENT_ID} with the values you noted from your Auth0 application's "Settings" tab.

Creating Login and Logout Buttons

Now let's create login and logout buttons for users to interact with. In the index.js file, replace the existing code with the following:

import React from 'react';
import { useAuth0 } from '@auth0/auth0-react';

function Index() {
  const { loginWithRedirect, isAuthenticated, logout } = useAuth0();

  return (
    <div>
      {!isAuthenticated && (
        <button onClick={() => loginWithRedirect()}>Log In</button>
      )}
      {isAuthenticated && (
        <button onClick={() => logout({ returnTo: window.location.origin })}>Log Out</button>
      )}
    </div>
  );
}

export default Index;

This code will display a "Log In" button when the user is not authenticated and a "Log Out" button when the user is authenticated. Users can now log in and log out through Auth0's secure login page.

Securing Routes with Auth0

In this step, we will demonstrate how to secure a Next.js route by checking if the user is authenticated before rendering a protected page. We will assume you have a protected page called secret.js in the pages directory:

import React from 'react';

function Secret() {
  return <div>This is a secret page. You must be logged in to view this content.</div>;
}

export default Secret;

To protect this route, we can use Auth0's withAuthenticationRequired function. Modify the secret.js file like this:

import React from 'react';
import { withAuthenticationRequired } from '@auth0/auth0-react';

function Secret() {
  return <div>This is a secret page. You must be logged in to view this content.</div>;
}

export default withAuthenticationRequired(Secret);

Now, if a user tries to access the /secret route without being authenticated, they will be redirected to the Auth0 login page.

Conclusion

In this tutorial, we have demonstrated how to integrate Auth0 in a Next.js application for effortless authentication. By following these steps, you can effectively secure your application and protect your users' data from cyber threats. Keep in mind that security is an ongoing process, and you should always stay informed on best practices and emerging security technologies.