How to build a public Google Chat integration: Building the Auth Flow

Hey there, fellow JavaScript devs! Ready to dive into the world of Google Chat integrations? Today, we're focusing on one of the most crucial aspects: building a rock-solid auth flow. Let's get started!

Introduction

Google Chat integrations are a fantastic way to extend the platform's functionality, but they're only as good as their authorization. We'll be walking through the process of creating a secure, user-friendly auth flow that'll make your integration shine.

Prerequisites

Before we jump in, make sure you've got:

• A Google Cloud Console project set up
• The necessary APIs enabled (Google Chat API, Google People API)
• OAuth 2.0 credentials ready to go

If you're not there yet, take a quick detour to the Google Cloud Console and get those ducks in a row.

OAuth 2.0 Flow Overview

We'll be implementing the authorization code flow for web applications. It's the most secure option for server-side apps, and it's what Google recommends for Chat integrations.

Implementing the Auth Flow

Initiating the Authorization Request

First things first, let's construct that authorization URL:

const authUrl = new URL('https://accounts.google.com/o/oauth2/v2/auth');
authUrl.searchParams.append('client_id', YOUR_CLIENT_ID);
authUrl.searchParams.append('redirect_uri', YOUR_REDIRECT_URI);
authUrl.searchParams.append('response_type', 'code');
authUrl.searchParams.append('scope', 'https://www.googleapis.com/auth/chat.bot');

Pro tip: Be selective with your scopes. Only ask for what you need!

Handling the Authorization Response

Once the user grants permission, Google will redirect them back to your redirect_uri with an authorization code. Grab it like this:

const urlParams = new URLSearchParams(window.location.search);
const authCode = urlParams.get('code');

Remember, treat this code like it's radioactive. It's a one-time use token, so handle it with care!

Exchanging the Code for Tokens

Now, let's swap that code for some juicy tokens:

const tokenResponse = await fetch('https://oauth2.googleapis.com/token', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/x-www-form-urlencoded',
  },
  body: new URLSearchParams({
    code: authCode,
    client_id: YOUR_CLIENT_ID,
    client_secret: YOUR_CLIENT_SECRET,
    redirect_uri: YOUR_REDIRECT_URI,
    grant_type: 'authorization_code',
  }),
});

const { access_token, refresh_token } = await tokenResponse.json();

Storing and Refreshing Tokens

Store these tokens securely - never expose them to the client side! When the access token expires, use the refresh token to get a new one:

const refreshResponse = await fetch('https://oauth2.googleapis.com/token', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/x-www-form-urlencoded',
  },
  body: new URLSearchParams({
    refresh_token: storedRefreshToken,
    client_id: YOUR_CLIENT_ID,
    client_secret: YOUR_CLIENT_SECRET,
    grant_type: 'refresh_token',
  }),
});

const { access_token } = await refreshResponse.json();

Integrating Auth Flow with Google Chat API

Now that you've got your access token, you're ready to make API requests:

const chatResponse = await fetch('https://chat.googleapis.com/v1/spaces/SPACE_NAME/messages', {
  method: 'POST',
  headers: {
    'Authorization': `Bearer ${access_token}`,
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    text: 'Hello, Chat!',
  }),
});

If you get a 401 error, it's time to refresh that token!

Best Practices

• Handle errors gracefully. Users should never see a raw error message.
• Make the auth process as smooth as possible. Nobody likes a clunky login flow.
• Always use HTTPS. Security isn't optional!

Testing and Debugging

Ran into issues? Don't sweat it! Here are some common pitfalls:

• Mismatched redirect URIs
• Incorrect scopes
• Expired tokens

The OAuth 2.0 Playground is your friend here. Use it to test your flow and see what's going on under the hood.

Conclusion

And there you have it! You've just built a robust auth flow for your Google Chat integration. Remember, authorization is the foundation of your app's security, so take the time to get it right.

Next up, you'll want to focus on building out your integration's functionality. But that's a story for another day. Happy coding, and may your tokens always be fresh!