If you want to redirect traffic from www.example.com to example.com using Amazon CloudFront, you’ll quickly discover CloudFront doesn’t support this out of the box.

The simple solution is to attach a Lambda@Edge function to the viewer-request event that detects requests to www. and issues a 301 redirect.

Here’s what happens on each request:

sequenceDiagram
    participant Viewer
    participant CloudFront
    participant Lambda as LambdaAtEdge
    Viewer->>CloudFront: GET www.example.com
    CloudFront->>Lambda: viewer-request event
    Lambda-->>CloudFront: 301 to example.com
    CloudFront-->>Viewer: 301 Moved Permanently
    Viewer->>CloudFront: GET example.com
  

Here’s a quick example:

'use strict';

exports.handler = async (event) => {
  const request = event.Records[0].cf.request;
  const headers = request.headers;

  const hostHeader = headers['host'][0].value;
  if (hostHeader.startsWith('www.')) {
    const newHost = hostHeader.replace(/^www\./, '');
    const redirectUrl = `https://${newHost}${request.uri}`;
    return {
      status: '301',
      statusDescription: 'Moved Permanently',
      headers: {
        location: [{
          key: 'Location',
          value: redirectUrl,
        }],
      },
    };
  }

  return request;
};

✅ Key points:

• Attach this Lambda@Edge function at the viewer-request event.
• It ensures canonical URLs and avoids duplicate content issues.
• Improves SEO by redirecting www traffic consistently to the apex domain.