How to build a public Travis CI integration: Building the Auth Flow

Hey there, fellow JavaScript enthusiasts! Ready to dive into the world of Travis CI integrations? Let's roll up our sleeves and build an auth flow that'll make your integration shine. We'll keep things concise and focused, so you can get up and running in no time.

Introduction

Travis CI is a powerhouse for continuous integration, and building a public integration can take your project to the next level. The key to a rock-solid integration? A bulletproof authorization flow. Let's make it happen!

Prerequisites

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

• Node.js and npm installed
• A basic understanding of OAuth 2.0
• Familiarity with the Travis CI API

Got all that? Great! Let's get coding.

Setting up the project

First things first, let's set up our project:

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

Implementing the OAuth 2.0 flow

Registering your application

Head over to Travis CI and register your application. You'll get a client ID and secret – guard these with your life!

Configuring OAuth 2.0 client

Create a .env file and add your credentials:

TRAVIS_CI_CLIENT_ID=your_client_id
TRAVIS_CI_CLIENT_SECRET=your_client_secret
REDIRECT_URI=http://localhost:3000/callback

Implementing the authorization request

Let's create our server.js:

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

const app = express();

app.get('/login', (req, res) => {
  const authUrl = `https://app.travis-ci.com/oauth/authorize?client_id=${process.env.TRAVIS_CI_CLIENT_ID}&redirect_uri=${process.env.REDIRECT_URI}&response_type=code&scope=read_user`;
  res.redirect(authUrl);
});

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

Handling the callback and token exchange

Now, let's add the callback handler:

app.get('/callback', async (req, res) => {
  const { code } = req.query;
  try {
    const response = await axios.post('https://api.travis-ci.com/oauth/token', {
      client_id: process.env.TRAVIS_CI_CLIENT_ID,
      client_secret: process.env.TRAVIS_CI_CLIENT_SECRET,
      code,
      redirect_uri: process.env.REDIRECT_URI,
      grant_type: 'authorization_code'
    });
    const { access_token } = response.data;
    // Store the access token securely
    res.send('Authorization successful!');
  } catch (error) {
    res.status(500).send('Authorization failed');
  }
});

Storing and managing access tokens

For this demo, we'll keep it simple and store the token in memory. In a real-world scenario, you'd want to use a secure database or key management system.

let accessToken = null;

// In the callback handler:
accessToken = response.data.access_token;

Making authenticated requests to Travis CI API

Now that we have our token, let's use it:

app.get('/user', async (req, res) => {
  try {
    const response = await axios.get('https://api.travis-ci.com/user', {
      headers: {
        'Authorization': `token ${accessToken}`,
        'Travis-API-Version': '3'
      }
    });
    res.json(response.data);
  } catch (error) {
    res.status(500).send('Error fetching user data');
  }
});

Error handling and edge cases

Always expect the unexpected! Add try-catch blocks and handle common errors gracefully. For example:

if (!accessToken) {
  return res.status(401).send('Unauthorized: No access token');
}

Testing the auth flow

Testing is crucial! Write unit tests for your auth components and integration tests for the entire flow. Here's a quick example using Jest:

test('authorization request redirects to Travis CI', async () => {
  const response = await request(app).get('/login');
  expect(response.status).toBe(302);
  expect(response.header.location).toContain('app.travis-ci.com/oauth/authorize');
});

Security considerations

Remember these golden rules:

• Always use HTTPS in production
• Implement token revocation
• Protect against CSRF attacks by using state parameters in your auth requests

Conclusion

And there you have it! You've just built a solid auth flow for your Travis CI integration. From here, you can expand your integration to do all sorts of cool things with the Travis CI API.

Remember, the key to a great integration is a secure and smooth auth flow. Keep iterating, keep learning, and most importantly, keep coding!

Happy integrating, folks! 🚀