How to build a public Fastly integration: Building the Auth Flow

Hey there, fellow JavaScript aficionados! Ready to dive into the world of Fastly integrations? Today, we're going to tackle one of the most crucial aspects of building a public integration: the authorization flow. Buckle up, because we're about to make your Fastly integration secure and user-friendly in no time!

The Lowdown on Fastly Integration

Before we jump in, let's quickly touch on why we're here. Fastly integrations are awesome for extending the functionality of your apps, but without a solid auth flow, you're basically leaving your front door wide open. We don't want that, do we? So, let's get cracking on building a bulletproof authorization system!

What You'll Need

Alright, before we start coding, make sure you've got these essentials:

• A Fastly account with API credentials (you're cool, so I know you've got this)
• Node.js environment set up and ready to roll
• A decent grasp of OAuth 2.0 (don't worry, we'll refresh your memory as we go)

Setting Up Shop

First things first, let's get our project off the ground:

mkdir fastly-integration && cd fastly-integration
npm init -y
npm install express axios dotenv

Easy peasy, right? Now we've got our basic structure and dependencies in place.

Fastly API: Your New Best Friend

Head over to your Fastly account and create a new application. Grab that client ID and client secret – they're your golden tickets. Now, let's keep them safe:

touch .env

In your .env file:

FASTLY_CLIENT_ID=your_client_id_here
FASTLY_CLIENT_SECRET=your_client_secret_here

Remember, keep this file out of version control. We don't want any unwanted guests at our party!

The Main Event: Authorization Flow

Now for the fun part! Let's break down the auth flow:

1. Create an authorization URL
2. Handle the redirect and exchange the code for a token
3. Store and refresh those precious access tokens

Here's a quick example to get you started:

const express = require('express');
const axios = require('axios');
require('dotenv').config();

const app = express();

app.get('/auth', (req, res) => {
  const authUrl = `https://api.fastly.com/oauth/authorize?client_id=${process.env.FASTLY_CLIENT_ID}&scope=global&response_type=code`;
  res.redirect(authUrl);
});

app.get('/callback', async (req, res) => {
  const { code } = req.query;
  try {
    const response = await axios.post('https://api.fastly.com/oauth/token', {
      grant_type: 'authorization_code',
      client_id: process.env.FASTLY_CLIENT_ID,
      client_secret: process.env.FASTLY_CLIENT_SECRET,
      code,
    });
    // Store the access token securely
    console.log(response.data);
    res.send('Authorization successful!');
  } catch (error) {
    console.error('Error exchanging code for token:', error);
    res.status(500).send('Authorization failed');
  }
});

app.listen(3000, () => console.log('Server running on port 3000'));

Locking It Down

Security is sexy, so let's add some PKCE (Proof Key for Code Exchange) to our flow:

const crypto = require('crypto');

function generateCodeVerifier() {
  return crypto.randomBytes(32).toString('hex');
}

function generateCodeChallenge(verifier) {
  return crypto.createHash('sha256').update(verifier).digest('base64')
    .replace(/\+/g, '-').replace(/\//g, '_').replace(/=/g, '');
}

// Use these in your /auth route
const codeVerifier = generateCodeVerifier();
const codeChallenge = generateCodeChallenge(codeVerifier);

Don't forget to include the code_challenge in your authorization URL and the code_verifier when exchanging the code for a token!

Taking It for a Spin

Fire up your server and navigate to http://localhost:3000/auth. If all goes well, you should be redirected to Fastly, asked to authorize, and then sent back to your callback URL with a shiny new access token. Feels good, doesn't it?

Handling the Curveballs

Of course, things don't always go smoothly. Make sure you're handling errors gracefully:

app.get('/callback', async (req, res) => {
  // ... existing code ...
  try {
    // ... token exchange ...
  } catch (error) {
    console.error('Error:', error.response ? error.response.data : error.message);
    res.status(500).send('Oops! Something went wrong. Please try again.');
  }
});

And don't forget about token refresh! Set up a mechanism to refresh your access token before it expires.

Pro Tips

1. Store tokens securely: Consider using encrypted storage or a secure database.
2. Implement token revocation: Give users the power to revoke access when they want.
3. Mind your manners: Respect Fastly's rate limits and optimize your API usage.

Wrapping Up

And there you have it, folks! You've just built a rock-solid authorization flow for your Fastly integration. Pat yourself on the back – you've taken a big step towards creating a secure, user-friendly integration.

Remember, this is just the beginning. From here, you can start adding all sorts of cool features to your integration. The sky's the limit!

Now go forth and integrate with confidence. You've got this! 🚀