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

Hey there, fellow JavaScript devs! Ready to dive into the world of Google Ad Manager integration? Today, we're focusing on the crucial part of building a robust authorization flow. Let's get started!

Introduction

Google Ad Manager integration can be a game-changer for your ad tech stack. But before you can start pulling reports or managing inventory, you need to nail the authorization flow. It's the gatekeeper that ensures your integration is secure and user-friendly.

Prerequisites

Before we jump in, make sure you've:

• Set up a Google Cloud Console project
• Enabled the necessary APIs (Google Ad Manager API, of course!)
• Created OAuth 2.0 credentials

Got all that? Great! Let's move on to the fun stuff.

OAuth 2.0 Flow Overview

We're using the Authorization Code Flow here. It's like a secret handshake between your app and Google, ensuring that only authorized users can access Ad Manager data. For this integration, you'll need to request the https://www.googleapis.com/auth/dfp scope.

Implementing the Auth Flow

Setting up the authorization endpoint

First, construct your authorization URL:

const authUrl = `https://accounts.google.com/o/oauth2/v2/auth?
  client_id=${YOUR_CLIENT_ID}&
  redirect_uri=${YOUR_REDIRECT_URI}&
  scope=https://www.googleapis.com/auth/dfp&
  response_type=code&
  access_type=offline`;

Handling the redirect and token exchange

After the user grants permission, Google will redirect them back to your app with an authorization code. Exchange this for an access token:

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',
  }),
});

Storing and refreshing access tokens

Store the access token securely and set up a mechanism to refresh it when it expires. Trust me, your future self will thank you!

Building the Frontend

Keep it simple! A "Connect to Google Ad Manager" button that triggers the auth flow is all you need. Here's a quick example:

function initiateAuth() {
  window.location.href = authUrl;
}

Backend Implementation

On your server, set up an endpoint to handle the token exchange. Store the tokens securely (please, not in plain text!) and implement a refresh mechanism. Here's a basic Express.js example:

app.get('/oauth/callback', async (req, res) => {
  const { code } = req.query;
  // Exchange code for tokens
  // Store tokens securely
  // Redirect user to success page
});

Integrating with Google Ad Manager API

Now that you have your access token, you can start making API requests:

const response = await fetch('https://googleads.googleapis.com/v11/customers/{customerId}/campaigns', {
  headers: {
    'Authorization': `Bearer ${accessToken}`,
    'Content-Type': 'application/json',
  },
});

Best Practices and Security Considerations

• Never expose your client secret on the frontend
• Implement PKCE for added security (it's easier than it sounds!)
• Regularly rotate refresh tokens

Testing and Debugging

Hitting a snag? Don't sweat it! Check out Google's OAuth 2.0 Playground to test your flow. Common issues often involve incorrect scopes or mismatched redirect URIs.

Conclusion

And there you have it! You've just built a solid auth flow for your Google Ad Manager integration. Remember, a robust auth implementation is the foundation of a great integration. From here, the ad tech world is your oyster!

Keep coding, stay curious, and may your API calls always return 200 OK! 🚀