Edge Functions

Edge Functions are server-side TypeScript functions, distributed globally at the edge—close to your users. They can be used for listening to webhooks or integrating your Supabase project with third-parties like Stripe.

Edge Functions are developed using Deno, which offers a few benefits to you as a developer:

• It is open source.
• It is portable. Supabase Edge Functions run locally, and on any other Deno-compatible platform (including self-hosted infrastructure).
• It is TypeScript first and supports WASM.
• Edge Functions are globally distributed for low-latency.

Quickstart#

Learn how to develop Edge Functions in less than 7 minutes:

Prerequisites#

Follow the steps to prepare your Supabase project on your local machine.

• Install the Supabase CLI. Docs.
• Login to the CLI using the command: supabase login. Docs.
• Initialize Supabase inside your project using the command: supabase init. Docs.
• Link to your Remote Project using the command supabase link --project-ref your-project-ref. Docs.
• Optional: Setup your environment: Follow this setup guide to integrate the Deno language server with your editor.

Getting Started#

Let's build an Edge Function locally, then deploy it to the Supabase Platform.

Creating a function#

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

supabase functions new hello-world

This creates a function stub in your supabase folder at ./functions/hello-world/index.ts.

Deploy to production#

supabase functions deploy hello-world

This command bundles your Edge Function from ./functions/hello-world/index.ts and deploys it to the Supabase platform. The command outputs a URL to the Supabase Dashboard which you can open to find view more details. Let's open the link to find the execution command.

Executing Remote Functions#

You can execute Edge Functions using curl. Copy the curl command from the Dashboard. It should look like this:

curl --request POST 'https://<project_ref>.functions.supabase.co/hello-world' \
  --header 'Authorization: Bearer ANON_KEY' \
  --header 'Content-Type: application/json' \
  --data '{ "name":"Functions" }'

If you receive an error Invalid JWT, find the ANON_KEY of your project in the Dashboard under Settings > API.

After invoking your Edge Function you should see the response { "message":"Hello Functions!" }.

Debugging your Functions#

You can debug your deployed Edge Functions using the "Functions" section of the Dashboard. There are two types debugging tools available:

• Invocations: shows the Request and Response for each execution.
• Logs: shows any platform events, including deployments and errors.

Developing locally#

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

supabase start # start the supabase stack
supabase functions serve hello-world # start the Function watcher

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

Invoking Functions locally#

While serving your local Function, you can execute it using curl:

curl --request POST 'http://localhost:54321/functions/v1/hello-world' \
  --header 'Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJzdXBhYmFzZS1kZW1vIiwicm9sZSI6ImFub24ifQ.625_WdcF3KHqz5amU0x2X5WWHP-OEs_4qj0ssLNHzTs' \
  --header 'Content-Type: application/json' \
  --data '{ "name":"Functions" }'

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

If you execute 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!

Secrets and Environment Variables#

It's common that you will need to use sensitive information or environment-specific variables inside your Edge Functions. You can access these using Deno's built-in handler

1Deno.env.get(MY_SECRET_NAME)

Default secrets#

By default, Edge Functions have access to these secrets:

• SUPABASE_URL: The API gateway for your Supabase project.
• SUPABASE_ANON_KEY: The anon key for your Supabase API. This is safe to use in a browser when you have Row Level Security enabled.
• SUPABASE_SERVICE_ROLE_KEY: The service_role key for your Supabase API. This is safe to use in Edge Functions, but it should NEVER be used in a browser. This key will bypass Row Level Security.
• SUPABASE_DB_URL: The URL for your PostgreSQL database. You can use this to connect directly to your database.

Local secrets#

Let's create a local file for storing our secrets, and inside it we can store a secret MY_NAME:

1echo "MY_NAME=Yoda" >> ./supabase/.env.local

This creates a new file ./supabase/.env.local for storing your local development secrets.

Now let's access this environment variable MY_NAME inside our Function. Anywhere in your function, add this line:

1console.log(Deno.env.get('MY_NAME'))

Now we can invoke our function locally, by serving it with our new .env.local file:

supabase functions serve hello-world --env-file ./supabase/.env.local

When the function starts you should see the name “Yoda” output to the terminal.

Production secrets#

Let's create a .env for production. In this case we'll just use the same as our local secrets:

cp ./supabase/.env.local ./supabase/.env

This creates a new file ./supabase/.env for storing your production secrets.

Let's push all the secrets from the .env file to our remote project using supabase secrets set:

supabase secrets set --env-file ./supabase/.env

# You can also set secrets individually using:
supabase secrets set MY_NAME=Chewbacca

You don't need to re-deploy after setting your secrets.

To see all the secrets which you have set remotely, use supabase secrets list:

supabase secrets list

Suggestions#

Database Functions vs Edge Functions#

For data-intensive operations we recommend using Database Functions, which are executed within your database and can be called remotely using the REST and GraphQL API.

For use-cases which require low-latency we recommend Edge Functions, which are globally-distributed and can be written in TypeScript.

Organizing your Edge Functions#

We recommend developing “fat functions”. This means that you should develop few large functions, rather than many small functions. One common pattern when developing Functions is that you need to share code between two or more Functions. To do this, you can store any shared code in a folder prefixed with an underscore (_). We recommend this folder structure:

└── supabase
    ├── functions
    │   ├── _shared
    │   |   ├── supabaseAdmin.ts # Supabase client with SERVICE_ROLE key
    │   │   └── supabaseClient.ts # Supabase client with ANON key
    │   ├── function-one # use hyphens to name functions
    │   │   └── index.ts
    │   └── function-two
    │       └── index.ts
    ├── migrations
    └── config.toml

Naming Edge Functions#

We recommend using hyphens to name functions because hyphens are the most URL-friendly of all the naming conventions (snake_case, camelCase, PascalCase).

CORS (Cross-Origin Resource Sharing)#

We recommend adding a check to handle CORS Preflight requests in your edge function to be able to invoke the function from browsers.

See the example on GitHub.

1export const corsHeaders = {
2  'Access-Control-Allow-Origin': '*',
3  'Access-Control-Allow-Headers': 'authorization, x-client-info, apikey',
4}
5
6serve(async (req) => {
7  if (req.method === 'OPTIONS') {
8    return new Response('ok', { headers: corsHeaders })
9  }
10  ...
11})

Using HTTP Methods#

Edge Functions supports GET, POST, PUT, PATCH, DELETE, and OPTIONS. A function can be designed to perform different actions based on a request's HTTP method. See the example on building a RESTful service to learn how to handle different HTTP methods in your function.

Limitations#

• Deno Deploy limitations
  • Deno does not support outgoing connections to ports 25, 465, and 587.
  • Cannot write to File System
• Edge Functions
  • Local development - only one function at a time
  • Serving of HTML content is not supported (GET requests that return text/html will be rewritten to text/plain).