Auth and User Demo

Uses SvelteKit, Supabase, and SSR Auth.

Code Showcase

• Email sign-up/sign-in.
• Anon sign in.
• GitHub sign-in. Can easily be changed to other oauth providers.
• Requires a session to access all pages under the authenticated layout group.
• Add, change, remove custom nickname user_metadata on the /self page.

All sign-up and sign-ins happen server-side.

Prerequisites

1. A Supabase account.
2. A Supabase project.

Install

git clone https://github.com/j4w8n/sveltekit-supabase-ssr.git
cd sveltekit-supabase-ssr
npm install

Setup

1. Environment variables.

   Create a .env.local file in your project's root directory, adding the below. The values can be found in your Supabase project's dashboard at Project Settings > API. !!! Never expose your JWT_SECRET on the client side !!!

   PUBLIC_SUPABASE_ANON_KEY=<your-project-anon-key>
   PUBLIC_SUPABASE_URL=https://<your-project-id>.supabase.co
   JWT_SECRET=<your-project-jwt-secret>
   

2. If using the demo's signup or magiclink login, change your email template links per the below. You can find these settings in your Supabase project's dashboard at Authentication > Email Templates.

   • Confirm signup: href="{{ .SiteURL }}/auth/confirm?token_hash={{ .TokenHash }}&type=email"
   • Magic Link: href="{{ .SiteURL }}/auth/confirm?token_hash={{ .TokenHash }}&type=email"

3. Site URL and Redirect URLs

   Login to your Supabase dashboard, then go to your project > Authentication > URL Configuration, and add these:

   • Site:
     • http://localhost:5173
   • Redirects:
     • http://localhost:5173/auth/confirm
     • http://localhost:5173/auth/callback

Run!

npm run dev

Open a browser to http://localhost:5173

Security

Within the (authenticated) layout group, we have a +page.server.ts file for each route. This ensures that even during client navigation we can verify there's still a session before rendering the page.

We check for and fully validate the session by calling event.locals.getSession(). Inside that function, we verify the access_token, aka JWT, and use it's decoded contents to help create a validated session for use on the server-side.

Full validation is important because sessions are stored in a cookie sent from a client. The client could be an attacker with just enough information to bypass checks within supabase.auth.getSession() and possibly render data for a victim user. See this discussion for details.

!!! Simply verifying the JWT does not validate the session.user object, for using it's info to render sensitive user data on the server-side. See discussion link above. !!!