SvelteKit Auth: A Comprehensive Guide to Authentication

What is SvelteKit Auth?

SvelteKit Auth is a SvelteKit module designed to provide authentication for SvelteKit applications. Leveraging the power of Auth.js, SvelteKit Auth enables developers to add authentication providers and customize the authentication flow of their app.

Setting Up SvelteKit Auth

To get started with SvelteKit Auth, we need to create a new SvelteKit project and add AWS Cognito authentication to it. Here’s a step-by-step guide:

1. Create a new SvelteKit project: Use the official guide to scaffold a new SvelteKit project with TypeScript.
2. Add SvelteKit Auth: Install the latest version of SvelteKit Auth using npm or yarn.
3. Set up AWS Cognito: Create a new AWS Cognito user pool and app client, following the official guide.
4. Add custom credentials auth: Implement custom credentials auth in your SvelteKit project using the Credentials function from SvelteKit Auth.

# Install SvelteKit Auth using npm
npm install @sveltejs/kit-auth

# Install SvelteKit Auth using yarn
yarn add @sveltejs/kit-auth

Implementing SvelteKit Auth

With our setup complete, let’s implement SvelteKit Auth in our application:

• Create a root layout: Design a root layout that will be used by all pages, leveraging SvelteKit Auth’s session data.
• Redirect to login page: Create a login page and use SvelteKit Auth’s signIn function to authenticate users.
• Session and redirection: Use SvelteKit Auth’s session data to check user authorization and redirect users to authenticated routes.

// Example of using SvelteKit Auth's signIn function
import { signIn } from '@sveltejs/kit-auth';

const Login = () => {
  const handleSubmit = async (event) => {
    event.preventDefault();
    const { email, password } = event.target;
    try {
      await signIn('credentials', {
        email,
        password,
      });
      // Redirect to protected route
    } catch (error) {
      console.error(error);
    }
  };

  return (
    <form onSubmit={handleSubmit}>
      <label>Email:</label>
      <input type="email" name="email" />
      <br />
      <label>Password:</label>
      <input type="password" name="password" />
      <br />
      <button type="submit">Login</button>
    </form>
  );
};

export default Login;

Advanced Layout Techniques

To ensure authenticated routes are not accessible to unauthenticated users, we can leverage SvelteKit’s advanced layout technique by placing all authenticated routes under a specific directory.

This approach allows us to easily manage access control and protect sensitive areas of our application.

Example:

// routes/
//   __layout.svelte
//   public/
//     index.svelte
//   private/
//     dashboard.svelte
//     settings.svelte

In this example, the private directory contains routes that require authentication. We can use SvelteKit Auth’s session data to check user authorization and redirect users to authenticated routes.