Building and deploying Supabase Edge Functions: project structure, environment variables, CORS handling, client invocation, and error handling.
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Edge Functions are server-side TypeScript functions that run on Deno Deploy, distributed globally at the edge.
supabase/
functions/
my-function/
index.ts # Entry point (required)
shared/
cors.ts # Shared utilities
types.tsEach function lives in its own directory under supabase/functions/.
import { serve } from "https://deno.land/std@0.177.0/http/server.ts";
serve(async (req: Request) => {
const { name } = await req.json();
return new Response(
JSON.stringify({ message: `Hello, ${name}!` }),
{ headers: { "Content-Type": "application/json" } }
);
});Create a shared CORS utility:
// supabase/functions/shared/cors.ts
export const corsHeaders = {
"Access-Control-Allow-Origin": "*",
"Access-Control-Allow-Headers": "authorization, x-client-info, apikey, content-type",
};Use in your function:
import { corsHeaders } from "../shared/cors.ts";
serve(async (req: Request) => {
// Handle CORS preflight
if (req.method === "OPTIONS") {
return new Response("ok", { headers: corsHeaders });
}
// Your logic here
return new Response(
JSON.stringify({ data: "result" }),
{ headers: { ...corsHeaders, "Content-Type": "application/json" } }
);
});Set secrets via CLI:
supabase secrets set MY_API_KEY=sk-xxx
supabase secrets listAccess in code:
const apiKey = Deno.env.get("MY_API_KEY");Built-in variables (always available):
SUPABASE_URLSUPABASE_ANON_KEYSUPABASE_SERVICE_ROLE_KEYSUPABASE_DB_URLconst { data, error } = await supabase.functions.invoke("my-function", {
body: { name: "World" },
});The client automatically sends the user's auth token in the Authorization header.
serve(async (req: Request) => {
try {
const body = await req.json();
if (!body.email) {
return new Response(
JSON.stringify({ error: "email is required" }),
{ status: 400, headers: { "Content-Type": "application/json" } }
);
}
// process...
return new Response(JSON.stringify({ success: true }), {
headers: { "Content-Type": "application/json" },
});
} catch (err) {
return new Response(
JSON.stringify({ error: "Internal server error" }),
{ status: 500, headers: { "Content-Type": "application/json" } }
);
}
});# Deploy a single function
supabase functions deploy my-function
# Deploy all functions
supabase functions deploy
# Local development
supabase functions serve my-function --env-file .env.localcurl -i --location --request POST \
http://localhost:54321/functions/v1/my-function \
--header 'Authorization: Bearer YOUR_ANON_KEY' \
--header 'Content-Type: application/json' \
--data '{"name": "World"}'