Provides helpers to enable authentication using Supabase in SvelteKit applications.

This library is probably not production ready. It hasn't been tested in anger, and it might not follow the best practises for SvelteKit or Supabase.

If you're considering using it, please review the code carefully, and feel free to send PRs if you find any mistakes or improvements.

npm add sveltekit-supabase-authentication

npm add https://github.com/Thau/sveltekit-supabase-authentication

The flow of this library is this:

1. We hook on supabase.auth.onAuthStateChange. This hook will call make an API call to /api/setAuthCookie when a successful login happens and another call to /api/destroyAuthCookie when a successful logout happens. This is automatically handled by the SupabaseAuthentication component.
2. We add two SvelteKit hooks, handleAuth and addAuthToSession.
   • handleAuth takes care of several concerns:
     1. Creates the /api/setAuthCookie endpoint. This endpoint will be called by onAuthStateChange and will just return the headers to setup a cookie.
     2. Creates the /api/destroyAuthCookie endpoint. This endpoint will be called by onAuthStateChange and will return the headers to expire the session cookie.

First, we need to wrap our application in a SupabaseAuthentication component. The easiest way to do this is in a layout:

<script>
  import SupabaseAuthentication from 'sveltekit-supabase-authentication/SupabaseAuthentication.svelte';
  const supabase = INITIALIZED_SUPABASE_CLIENT;

  const openPaths = ['/'];
  const loginPath = '/login';
</script>

<SupabaseAuthentication {supabase} {openPaths} {loginPath}>
  <slot />
</SupabaseAuthentication>

openPaths is a list of all the paths that are public and don't require authorization. loginPath is the path of our login page.

There's several ways to install these hooks.

If you don't already have handle and getSession hooks in your hooks.js, the easiest way is to just import these and export them this way:

import { handleAuthCookie, addAuthToSession } from 'sveltekit-supabase-authentication/hooks';
const supabase = INITIALIZED_SUPABASE_CLIENT;

export const handle = handleAuthCookie(supabase);
export const getSession = addAuthToSession;

If you have any of these hooks with other functionality, you can instead compose handle using SvelteKit's sequence, like this:

import { sequence } from '@sveltejs/kit/hooks';
import { handleAuthCookie } from 'sveltekit-supabase-authentication/hooks';
const supabase = INITIALIZED_SUPABASE_CLIENT;

async function yourOwnHandle({ request, resolve }) {
  console.log('Your Own Handle');
  return await resolve(request);
}

export const handle = sequence(handleAuthCookie(supabase), yourOwnHandle);

It's important to pass an initialized Supabase client to handleAuthCookie so it can check the validity of the token in the cookie. Otherwise, it would be easy to create a fake cookie.

As for addAuthToSession, the best way would be to call it first in your getSession and merge the object with your session.

import { addAuthToSession } from 'sveltekit-supabase-authentication/hooks';

export function getSession(request) {
  const authSession = addAuthToSession(request);
  authSession.mySessionData = SESSION_DATA;
}