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Supabase Edge Functions — Serverless Compute at the Edge

DodaTech Updated 2026-06-28 5 min read

In this tutorial, you will learn about Supabase Edge Functions. We cover key concepts, practical examples, and best practices to help you master this topic.

Supabase Edge Functions are serverless functions running on Deno at global edge locations, enabling custom backend logic, webhooks, background processing, and API endpoints without managing servers.

What You'll Learn

By the end of this lesson you will create, deploy, and manage Edge Functions, use the Supabase client within functions, handle HTTP requests and responses, and integrate with database and storage services.

Why It Matters

Edge Functions let you run custom server-side logic close to your users. They handle webhooks from Stripe, process file uploads, send emails, and execute complex business rules that cannot be expressed in SQL.

Real-World Use

DodaZIP uses an Edge Function to process ZIP file uploads. When a file is uploaded to storage, the function is triggered, runs the compression analysis, updates the processing status in the database, and sends a notification via Realtime.

flowchart LR
    U[User] -->|Upload file| S[Supabase Storage]
    S -->|Trigger| EF[Edge Function]
    EF -->|Read| DB[(Database)]
    EF -->|Write status| DB
    EF -->|Notify| RT[Realtime]
    RT -->|Update UI| U
    style EF fill:#3ecf8e,color:#fff

Creating an Edge Function

Create and serve a local Edge Function.

# Install Supabase CLI (required for Edge Functions)
npm install supabase --save-dev

# Initialize Supabase locally
supabase init

# Create a new Edge Function
supabase functions new hello-world

# The function is created at:
# supabase/functions/hello-world/index.ts

// supabase/functions/hello-world/index.ts
// Basic Edge Function

import { serve } from "https://deno.land/std@0.192.0/http/server.ts"
import { createClient } from "https://esm.sh/@supabase/supabase-js@2"

serve(async (req) => {
  const { name } = await req.json()
  
  const supabase = createClient(
    Deno.env.get("SUPABASE_URL")!,
    Deno.env.get("SUPABASE_ANON_KEY")!
  )
  
  const data = {
    message: `Hello, ${name || "World"}!`,
    timestamp: new Date().toISOString(),
  }
  
  return new Response(
    JSON.stringify(data),
    { headers: { "Content-Type": "application/json" } }
  )
})

Deploying Edge Functions

Deploy functions to Supabase's global edge network.

# Deploy a function
supabase functions deploy hello-world

# Deploy with specific options
supabase functions deploy hello-world \
  --import-map supabase/functions/import_map.json

# List deployed functions
supabase functions list

# Delete a function
supabase functions delete hello-world

# Set secrets for a function
supabase secrets set STRIPE_API_KEY=sk_test_...

# deploy_functions.py
# Understanding edge function deployment

def deployment_steps():
    print("Edge Function Deployment Steps:")
    print("  1. Create function: supabase functions new function-name")
    print("  2. Write function logic in TypeScript")
    print("  3. Set environment secrets: supabase secrets set KEY=VALUE")
    print("  4. Deploy: supabase functions deploy function-name")
    print()
    print("Verification:")
    print("  supabase functions list           # List all functions")
    print("  curl https://project-ref.supabase.co/functions/v1/function-name")

deployment_steps()

Invoking Edge Functions

Call functions from the client SDK or HTTP.

# invoke_functions.py
# Call Edge Functions from Python

import os
from supabase import create_client

def invoke_function():
    supabase = create_client(
        os.getenv("SUPABASE_URL", "https://example.supabase.co"),
        os.getenv("SUPABASE_ANON_KEY", "your-anon-key")
    )
    
    # Invoke the hello-world function
    response = supabase.functions.invoke(
        "hello-world",
        invoke_options={"body": {"name": "Supabase User"}}
    )
    
    print(f"Function response: {response}")
    
    # Invoke with no body
    response = supabase.functions.invoke("hello-world")
    print(f"Default response: {response}")

invoke_function()

Common Patterns

Use Edge Functions for common backend tasks.

# function_patterns.py
# Common Edge Function patterns

def describe_patterns():
    patterns = {
        "Webhook Handler": "Receive Stripe/ webhook events, verify signatures, update database",
        "File Processor": "Process uploaded files, generate thumbnails, extract metadata",
        "Email Sender": "Send transactional emails via Resend or SendGrid",
        "Data Aggregator": "Query and transform data before sending to client",
        "Auth Hook": "Custom authentication logic, user validation, access checks",
        "Cron Job": "Scheduled tasks: cleanup old data, generate reports, sync services",
        "API Proxy": "Proxy requests to external APIs with your credentials",
    }
    
    print("Common Edge Function Patterns:")
    for pattern, desc in patterns.items():
        print(f"  {pattern:20s} | {desc}")

describe_patterns()

Common Mistakes

  1. Not setting environment secrets: Hardcoding API keys in function code exposes them. Use supabase secrets set and Deno.env.get().

  2. Missing CORS headers: Functions called from browsers need CORS headers to avoid cross-origin errors.

  3. Functions timing out: Edge Functions have a timeout limit (default 10 seconds). Long-running tasks should use async processing patterns.

  4. Not handling errors: Always wrap function logic in try/catch and return appropriate HTTP status codes.

  5. Over-fetching from database: Edge Functions are billed by execution time. Optimize database queries to minimize function duration.

Practice Questions

  1. What runtime do Supabase Edge Functions use? Deno, a secure runtime for JavaScript and TypeScript.

  2. How do you deploy an Edge Function? Run supabase functions deploy function-name from the CLI.

  3. How do you set secrets for an Edge Function? Use supabase secrets set KEY=VALUE and access them with Deno.env.get("KEY").

  4. How do you call an Edge Function from the client? Use supabase.functions.invoke("function-name", { body: data }).

  5. Challenge: Create an Edge Function that processes a Webhook from Stripe, verifies the signature, updates the subscription status in the database, and sends a confirmation email.

FAQ

Are Edge Functions included in the free tier?

Yes. The free tier includes 500,000 invocations per month.

What languages are supported?

Edge Functions support TypeScript, JavaScript, and any Deno-compatible language.

What is the execution timeout?

The default timeout is 10 seconds. Contact support for longer timeouts on paid plans.

Can I use npm packages?

Edge Functions use Deno, which supports npm packages via npm: specifiers.

How do I debug Edge Functions?

Use console.log for logging. View logs via supabase functions logs function-name.

Mini Project

Create an Edge Function that handles file processing:

  1. Triggered by a new file in a storage bucket
  2. Reads the file metadata
  3. Updates the database status
  4. Returns a processing summary
def file_processing_function():
    print("File Processing Function:")
    print()
    print("Trigger: File uploaded to storage bucket")
    print("Input: File path, metadata, user_id")
    print()
    print("Processing steps:")
    print("  1. Read file from storage")
    print("  2. Validate file type and size")
    print("  3. Run compression analysis")
    print("  4. Update database with results")
    print("  5. Send Realtime notification")
    print()
    print("Output: { status, file_id, processing_time, size_savings }")

file_processing_function()

What's Next

Next: Supabase SDK for using the client library in depth.

← Previous Supabase Storage Buckets — File Upload and Management Next → Supabase SDK — Using the Client Library for Database and Auth Operations

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