Implementing Google OAuth2 in a Web App: A Beginner’s Guide

Implementing Google OAuth2 in a Web App: A Beginner’s Guide

Hey there! If you’re venturing into the world of web development, you’ve probably heard of OAuth2. It’s a protocol that allows users to give third parties access to their resources (like their profiles or email addresses) without sharing their passwords. Pretty neat, right? Today, I’m going to walk you through the process of integrating Google OAuth2 into your web app in a way that’s straightforward and beginner-friendly.

What is OAuth2 Exactly?

Before we dive in, let’s take a quick detour to understand what OAuth2 is. OAuth2 is an open standard authorization framework. It allows your app to request access to user data on behalf of third-party services (in this case, Google), while keeping the user’s credentials safe and secure.

Why Google OAuth2?

Google’s OAuth2 is widely used because it’s secure, supported by a large organization, and users often have Google accounts. By integrating Google OAuth2, you can:

• Reduce the friction of onboarding users by allowing them to sign in with their existing Google account.
• Access Google user data to create personalized app experiences.
• Improve data security by allowing Google to handle password verification.

Setting Up Google OAuth2

#### Step 1: Create a Google Cloud Project

First things first! You’ll need to create a Google Cloud project to use OAuth2. Follow these steps:

1. Visit the [Google Cloud Console](https://console.cloud.google.com/).

2. Click on Select a project at the top and then New Project.

3. Name your project and select an organization if applicable, then click on Create.

#### Step 2: Configure OAuth Consent Screen

Now that you have a project, let’s configure your OAuth consent screen:

1. In the sidebar, navigate to APIs & Services > OAuth consent screen.

2. Select either Internal or External depending on if you’d like only users in your organization to have access.

3. Fill out the required fields like App Name, Support Email, and Developer Contact Info.

4. Under Scopes, you can add any additional information your app might need later, though for basic authentication you don’t need to add anything here.

5. Save your changes.

#### Step 3: Create OAuth 2.0 Credentials

Time to get those credentials:

1. Under APIs & Services, go to Credentials and click on Create Credentials.

2. Choose OAuth 2.0 Client IDs.

3. Select Web application and provide a name.

4. Add your application’s authorized redirect URIs. This is where Google will send the authentication responses. Typically, it looks like http://yourapp.com/auth/google/callback.

5. Click on Create and note down your Client ID and Client Secret. You’ll need these to connect your app to Google.

#### Step 4: Integrate Google OAuth2 in Your Web App

Now, let’s bring some code magic! For this demonstration, we’ll use Node.js and Express.

First, install the necessary libraries:

npm install express axios express-session

Set up a basic Express app:

const express = require('express');
const axios = require('axios');
const session = require('express-session');
const app = express();
app.use(session({
secret: 'your-secret-key',
resave: false,
saveUninitialized: true
}));

Create login and callback routes:

const clientID = 'YOUR_GOOGLE_CLIENT_ID';
const clientSecret = 'YOUR_GOOGLE_CLIENT_SECRET';
const redirectURI = 'http://localhost:3000/auth/google/callback';
app.get('/auth/google', (req, res) => {
const authURL = https://accounts.google.com/o/oauth2/auth?client_id=${clientID}&redirect_uri=${redirectURI}&response_type=code&scope=profile email;
res.redirect(authURL);
});
app.get('/auth/google/callback', async (req, res) => {
const { code } = req.query;
try {
const tokenResponse = await axios.post('https://oauth2.googleapis.com/token', null, {
params: {
client_id: clientID,
client_secret: clientSecret,
redirect_uri: redirectURI,
grant_type: 'authorization_code',
code
}
});
const { access_token } = tokenResponse.data;
const userInfoResponse = await axios.get(https://www.googleapis.com/oauth2/v2/userinfo?access_token=${access_token});
req.session.user = userInfoResponse.data;
res.redirect('/profile');
} catch (error) {
res.send('Authentication failed');
}
});
app.get('/profile', (req, res) => {
if (!req.session.user) {
return res.redirect('/auth/google');
}
res.send(Hello ${req.session.user.name}, you are logged in with your Google account!);
});
app.listen(3000, () => {
console.log('Server is running on http://localhost:3000');
});

This code snippet will:

• Create two routes: one to initiate the Google OAuth2 flow, and another to handle the callback from Google.
• Use the fetched user data to start a session and store the user information.
• Display a welcome message using the user’s Google profile name.

Tips and Practice Ideas

Great job! You now have the basic structure of a Google OAuth2 integration in your web app. Here are a few practice ideas to further solidify your understanding:

• Try adding additional Google API scopes to access more data.
• Implement error handling to gracefully handle failed authentication attempts.
• Experiment with different programming languages and frameworks to accomplish the same OAuth2 flow.

Conclusion

OAuth2 can seem intimidating at first, but once you’ve grasped the basics, it becomes an incredibly powerful tool in your web app development toolkit. By using Google OAuth2, you can streamline your app’s user experience and offer a layer of security that users trust. Remember, every time you practice implementing such features, you’re one step closer to mastering web development. Keep coding and have fun with your new superpower!

Got questions? Let me know in the comments. Happy coding!