Developing Edge Functions locally

Get started with Edge Functions on your local machine.

Let's create a basic Edge Function on your local machine and then invoke it using the Supabase CLI.

Initialize a project#

Create a new Supabase project in a folder on your local machine:

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supabase init

Create an Edge Function#

Let's create a new Edge Function called hello-world inside your project:

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supabase functions new hello-world

This creates a function stub in your supabase folder:

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└── supabase    ├── functions    │   └── hello-world    │   │   └── index.ts ## Your function code    └── config.toml

How to write the code#

The generated function uses native Deno.serve to handle requests. It gives you access to Request and Response objects.

Here's the generated Hello World Edge Function, that accepts a name in the Request and responds with a greeting:

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Deno.serve(async (req) => {  const { name } = await req.json()  const data = {    message: `Hello ${name}!`,  }  return new Response(JSON.stringify(data), { headers: { 'Content-Type': 'application/json' } })})

Running Edge Functions locally#

You can run your Edge Function locally using supabase functions serve:

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supabase start # start the supabase stacksupabase functions serve # start the Functions watcher

The functions serve command has hot-reloading capabilities. It will watch for any changes to your files and restart the Deno server.

Invoking Edge Functions locally#

While serving your local Edge Function, you can invoke it using curl or one of the client libraries. To call the function from a browser you need to handle CORS requests. See CORS.

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curl --request POST 'http://localhost:54321/functions/v1/hello-world' \  --header 'Authorization: Bearer SUPABASE_ANON_KEY' \  --header 'Content-Type: application/json' \  --data '{ "name":"Functions" }'

You should see the response { "message":"Hello Functions!" }.

If you execute the function with a different payload, the response will change.

Modify the --data '{"name":"Functions"}' line to --data '{"name":"World"}' and try invoking the command again.

Next steps#

Check out the Deploy to Production guide to make your Edge Function available to the world.

See the development tips for best practices.