Multi-Region CDN with CloudFront Functions

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Speed matters when you’re delivering content globally, but getting it right can be tricky. AWS’s recent update to CloudFront Functions helps solve that problem by making traffic routing more dynamic and much faster—no Lambda@Edge required. I tried it out in this PoC, and the results were great!

Here’s a quick rundown of what’s new, why it matters, and how I built a multi-region CDN setup that uses this feature to cut down latency and improve performance across the globe.

So, What Are CloudFront Functions?

CloudFront Functions are lightweight JavaScript functions that run at AWS edge locations—close to your users. They’re designed to be super fast and let you tweak how requests and responses are handled, right at the edge.

What’s New? Origin Modifications

Until now, if you wanted to route requests to different origins dynamically (like picking the closest server), Lambda@Edge was your tool. But it came with some drawbacks—higher latency and cost, especially for real-time or high-traffic scenarios.

Now, CloudFront Functions can change origin settings on the fly. That means you can:

  • Dynamically switch the origin server.
  • Send requests to any public HTTP endpoint.
  • Modify headers, timeouts, and more.

It’s faster and cheaper—and opens the door for smarter routing.

Why This Matters

Here are a few reasons why this update is a big deal:

  1. Lower Latency - Requests go to the nearest origin based on where the user is. Less travel time = faster load times.
  2. Cheaper Than Lambda@Edge - CloudFront Functions are more cost-effective and still give you great performance.
  3. More Control - You can set up all sorts of routing logic—like geolocation-based routing, fallback in case of downtime, or region-specific content.
  4. It Scales Automatically - Since it runs at the edge, it scales with your traffic without you needing to worry about it.

Multi-Region CDN PoC

To test all this, I built a quick Proof of Concept. It’s a simple setup, but it really shows the power of this approach for global content delivery.

How It’s Built

The setup includes:

  • S3 Buckets in multiple AWS regions, each acting as an origin for content.
  • CloudFront Distribution to serve as the global CDN layer, caching and delivering content.
  • CloudFront Function written in JavaScript, which routes each request to the closest origin based on the user’s geographic location.

How It Works

Here’s what happens when someone accesses the content:

  1. The user makes a request, which hits the CloudFront distribution.
  2. A CloudFront Function runs at the edge and figures out where the user is located.
  3. Based on that location, the function updates the origin to the nearest S3 bucket.
  4. The request is then forwarded to that bucket, and the content is delivered with minimal latency.

Trying It Out

For this demo, I deployed S3 buckets in four regions: us-east-1, eu-central-1, ap-southeast-2, and sa-east-1. Each bucket hosts a simple image labeled with the region name. When you visit the CloudFront distribution URL, you get the image from the region closest to you.

You can use a VPN to simulate access from different parts of the world and see the routing in action.

Want More?

I’ve also created an extended version of this setup with more features, like:

  • Automatic replication of content across regions.
  • Support for custom domains and HTTPS via Route 53 and ACM.
  • Access logging with CloudFront to track usage and performance.

Final Thoughts

AWS’s update to CloudFront Functions really changes the game for building global, high-performance CDNs. You don’t need to go full Lambda@Edge anymore—this gives you more flexibility and better performance without breaking the bank.