Supabase Functions, like any backend service, often need to handle user authentication and authorization. This ensures that only legitimate users can access specific data or perform certain actions. Supabase provides powerful tools that integrate seamlessly with your Functions to manage these aspects.
The core of Supabase's authentication system is built around JWTs (JSON Web Tokens). When a user logs in or signs up, Supabase issues a JWT that contains information about the user, including their unique ID and any associated roles or permissions. This token is then typically sent to the client application, which includes it in subsequent requests to your Supabase Functions.
When a request arrives at your Supabase Function, you can access this JWT and verify its authenticity. Supabase offers built-in mechanisms to help you with this process, making it straightforward to secure your API endpoints.
Here's how you can typically access and use the user's authentication information within a Supabase Function:
import { serve } from 'https://deno.land/std@0.177.0/http/server.ts';
import { cors } from 'https://deno.land/std@0.177.0/http/middleware/cors.ts';
console.log('Functions server listening on 8000');
serve({
async handler(req) {
const headers = new Headers();
headers.set('Access-Control-Allow-Origin', '*');
headers.set('Access-Control-Allow-Headers', '*, Authorization');
if (req.method === 'OPTIONS') {
return new Response('ok', { headers });
}
// Get the JWT from the Authorization header
const authorizationHeader = req.headers.get('Authorization');
if (!authorizationHeader) {
return new Response(JSON.stringify({ error: 'Authorization header is missing' }), {
status: 401,
headers: {
'Content-Type': 'application/json',
...Object.fromEntries(headers),
},
});
}
const token = authorizationHeader.replace('Bearer ', '');
// In a real-world scenario, you would verify this token against Supabase's public keys.
// For simplicity, we're just assuming it's valid and extracting user info.
// Supabase's client libraries or Edge Functions runtime can help with token verification.
// Example: Extracting user ID from a hypothetical decoded token payload
let userId = null;
try {
// This is a placeholder for actual JWT decoding and verification
// You would use a library like 'jose' or Supabase's internal mechanisms
const decodedToken = JSON.parse(atob(token.split('.')[1])); // Basic Base64 decode for example
userId = decodedToken.sub; // 'sub' is typically the user ID
} catch (error) {
console.error('Error decoding token:', error);
return new Response(JSON.stringify({ error: 'Invalid token' }), {
status: 401,
headers: {
'Content-Type': 'application/json',
...Object.fromEntries(headers),
},
});
}
if (!userId) {
return new Response(JSON.stringify({ er