Edge Functions Quickstart

Prerequisites

Before you begin, make sure you have:

A Supabase project (create one)
Supabase CLI installed
Deno installed (optional, for local development)

Install Supabase CLI

brew install supabase/tap/supabase

brew install supabase/tap/supabase

scoop bucket add supabase https://github.com/supabase/scoop-bucket.git
scoop install supabase

npm install -g supabase

Verify installation:

supabase --version

Create a Function

Initialize Your Project

If you haven’t already, initialize Supabase in your project:

supabase init

This creates a supabase directory with the following structure:

supabase/
├── config.toml
└── functions/

Create Your First Function

Create a new function called hello-world:

supabase functions new hello-world

This creates:

supabase/functions/
└── hello-world/
    └── index.ts

Write Function Code

Edit supabase/functions/hello-world/index.ts:

Deno.serve(async (req) => {
  const { name } = await req.json()
  
  const data = {
    message: `Hello ${name}!`,
    timestamp: new Date().toISOString()
  }

  return new Response(
    JSON.stringify(data),
    { headers: { 'Content-Type': 'application/json' } }
  )
})

Test Locally

Start Supabase Services

Start the local Supabase stack (requires Docker):

supabase start

This starts:

PostgreSQL database
Auth server
Realtime server
Storage server
Edge Functions runtime

Serve Your Function

Start the function locally:

supabase functions serve hello-world

You should see:

Serving hello-world at http://localhost:54321/functions/v1/hello-world

Test with curl

In another terminal, invoke the function:

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

Response:

{
  "message": "Hello Functions!",
  "timestamp": "2024-03-04T10:30:00.000Z"
}

Test with JavaScript

Create a test client:

import { createClient } from '@supabase/supabase-js'

const supabase = createClient(
  'http://localhost:54321',
  'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJzdXBhYmFzZS1kZW1vIiwicm9sZSI6ImFub24ifQ.625_WdcF3KHqz5amU0x2X5WWHP-OEs_4qj0ssLNHzTs'
)

const { data, error } = await supabase.functions.invoke('hello-world', {
  body: { name: 'World' }
})

if (error) {
  console.error('Error:', error)
} else {
  console.log('Response:', data)
}

Deploy to Production

Authenticate with your Supabase account:

supabase login

This opens a browser to generate an access token.

Link Your Project

Link to your Supabase project:

supabase link --project-ref your-project-ref

Find your project ref in the Supabase Dashboard under Settings > General.

Deploy the Function

Deploy your function:

supabase functions deploy hello-world

Output:

Deployed function hello-world in 2.3s
  https://your-project.supabase.co/functions/v1/hello-world

Test Production Function

Invoke the deployed function:

curl -L -X POST 'https://your-project.supabase.co/functions/v1/hello-world' \
  -H 'Authorization: Bearer YOUR_ANON_KEY' \
  -H 'Content-Type: application/json' \
  -d '{"name":"Production"}'

Replace YOUR_ANON_KEY with your project’s anon key from Settings > API in the Dashboard.

Add Business Logic

Connect to Database

Access your Supabase database from the function:

import { createClient } from 'npm:supabase-js@2'

Deno.serve(async (req) => {
  try {
    const supabaseClient = createClient(
      Deno.env.get('SUPABASE_URL') ?? '',
      Deno.env.get('SUPABASE_ANON_KEY') ?? '',
      {
        global: {
          headers: { Authorization: req.headers.get('Authorization')! }
        }
      }
    )

    // Query the database
    const { data, error } = await supabaseClient
      .from('users')
      .select('*')
      .limit(10)

    if (error) throw error

    return new Response(
      JSON.stringify({ users: data }),
      { headers: { 'Content-Type': 'application/json' } }
    )
  } catch (error) {
    return new Response(
      JSON.stringify({ error: error.message }),
      { 
        status: 500,
        headers: { 'Content-Type': 'application/json' }
      }
    )
  }
})

Add Authentication

Enforce authentication in your function:

import { createClient } from 'npm:supabase-js@2'

Deno.serve(async (req) => {
  const supabaseClient = createClient(
    Deno.env.get('SUPABASE_URL') ?? '',
    Deno.env.get('SUPABASE_ANON_KEY') ?? '',
    {
      global: {
        headers: { Authorization: req.headers.get('Authorization')! }
      }
    }
  )

  // Get authenticated user
  const { data: { user }, error: authError } = await supabaseClient.auth.getUser()

  if (authError || !user) {
    return new Response(
      JSON.stringify({ error: 'Unauthorized' }),
      { 
        status: 401,
        headers: { 'Content-Type': 'application/json' }
      }
    )
  }

  // User is authenticated
  return new Response(
    JSON.stringify({ 
      message: `Hello ${user.email}!`,
      userId: user.id
    }),
    { headers: { 'Content-Type': 'application/json' } }
  )
})

Handle CORS

Enable CORS for browser requests:

import { corsHeaders } from 'jsr:@supabase/supabase-js@2/cors'

Deno.serve(async (req) => {
  // Handle CORS preflight
  if (req.method === 'OPTIONS') {
    return new Response('ok', { headers: corsHeaders })
  }

  try {
    const { name } = await req.json()
    
    return new Response(
      JSON.stringify({ message: `Hello ${name}!` }),
      { 
        headers: { 
          ...corsHeaders, 
          'Content-Type': 'application/json' 
        }
      }
    )
  } catch (error) {
    return new Response(
      JSON.stringify({ error: error.message }),
      { 
        status: 400,
        headers: { 
          ...corsHeaders, 
          'Content-Type': 'application/json' 
        }
      }
    )
  }
})

Real-World Example: Send Email

Create a function to send emails with Resend:

Create the Function

supabase functions new send-email

Write the Code

// supabase/functions/send-email/index.ts
const RESEND_API_KEY = Deno.env.get('RESEND_API_KEY')

Deno.serve(async (req) => {
  try {
    const { to, subject, html } = await req.json()

    const res = await fetch('https://api.resend.com/emails', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'Authorization': `Bearer ${RESEND_API_KEY}`
      },
      body: JSON.stringify({
        from: 'onboarding@yourdomain.com',
        to,
        subject,
        html
      })
    })

    const data = await res.json()

    return new Response(
      JSON.stringify(data),
      { 
        status: 200,
        headers: { 'Content-Type': 'application/json' }
      }
    )
  } catch (error) {
    return new Response(
      JSON.stringify({ error: error.message }),
      { 
        status: 500,
        headers: { 'Content-Type': 'application/json' }
      }
    )
  }
})

Set Environment Variable

supabase secrets set RESEND_API_KEY=your_resend_api_key

Deploy

supabase functions deploy send-email

Invoke

const { data, error } = await supabase.functions.invoke('send-email', {
  body: {
    to: 'user@example.com',
    subject: 'Welcome!',
    html: '<h1>Welcome to our app!</h1>'
  }
})

Development Workflow

Watch Mode

Auto-reload on file changes:

supabase functions serve hello-world --no-verify-jwt

The --no-verify-jwt flag skips JWT verification for easier local testing.

Use Environment Variables Locally

Create .env.local:

# supabase/.env.local
RESEND_API_KEY=your_api_key
OPENAI_API_KEY=your_openai_key

Serve with environment variables:

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

Test with Postman

Import this cURL command into Postman:

curl -L -X POST 'http://localhost:54321/functions/v1/hello-world' \
  -H 'Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJzdXBhYmFzZS1kZW1vIiwicm9sZSI6ImFub24ifQ.625_WdcF3KHqz5amU0x2X5WWHP-OEs_4qj0ssLNHzTs' \
  -H 'Content-Type: application/json' \
  -d '{"name":"Postman"}'

Next Steps

Deploy Functions

Learn advanced deployment strategies and CI/CD

Environment Variables

Manage secrets and configuration

Debugging

Debug and monitor your functions

Troubleshooting

Function Not Found

If you get a 404 error:

Check the function name matches the directory name
Verify deployment: supabase functions list
Ensure you’re using the correct URL

CORS Errors

If browser requests fail:

Add CORS headers to your response
Handle OPTIONS requests
Include the Authorization header in CORS config

Authentication Errors

If auth doesn’t work:

Verify you’re passing the Authorization header
Check the JWT token is valid
Use --no-verify-jwt for local testing

​Prerequisites

​Install Supabase CLI

​Create a Function

​Initialize Your Project

​Create Your First Function

​Write Function Code

​Test Locally

​Start Supabase Services

​Serve Your Function

​Test with curl

​Test with JavaScript

​Deploy to Production

​Login to Supabase

​Link Your Project

​Deploy the Function

​Test Production Function

​Add Business Logic

​Connect to Database

​Add Authentication

​Handle CORS

​Real-World Example: Send Email

​Create the Function

​Write the Code

​Set Environment Variable

​Deploy

​Invoke

​Development Workflow

​Watch Mode

​Use Environment Variables Locally

​Test with Postman

​Next Steps

Deploy Functions

Environment Variables

Debugging

​Troubleshooting

​Function Not Found

​CORS Errors

​Authentication Errors

​Resources

Prerequisites

Install Supabase CLI

Create a Function

Initialize Your Project

Create Your First Function

Write Function Code

Test Locally

Start Supabase Services

Serve Your Function

Test with curl

Test with JavaScript

Deploy to Production

Login to Supabase

Link Your Project

Deploy the Function

Test Production Function

Add Business Logic

Connect to Database

Add Authentication

Handle CORS

Real-World Example: Send Email

Create the Function

Write the Code

Set Environment Variable

Deploy

Invoke

Development Workflow

Watch Mode

Use Environment Variables Locally

Test with Postman

Next Steps

Troubleshooting

Function Not Found

CORS Errors

Authentication Errors

Resources