CloudFront Google Tag Gateway

A CloudFront Function to route /metrics/* requests to Google Tag Gateway for Advertisers while preserving visitor geolocation information.

Features

• Routes /metrics/* requests to Google Tag Gateway
• Automatically forwards visitor country and region information
• Uses CloudFront Functions 2.0 runtime for optimal performance
• Configurable Google Tag Gateway domain

Setup

1. Configure the domain

   Edit function.js and replace the domain with your Google Tag Gateway endpoint:

   const GOOGLE_TAG_GATEWAY_DOMAIN = 'YOUR-TAG-ID.fps.goog';

2. Deploy to CloudFront

   Create a CloudFront Function using the AWS Console, CLI, or Infrastructure as Code:

   aws cloudfront create-function \
     --name google-tag-gateway \
     --function-config Runtime=cloudfront-js-2.0 \
     --function-code fileb://function.js

3. Associate with Distribution

   Add the function to your CloudFront distribution's viewer-request event.

How it Works

The function intercepts requests to /metrics/* paths and:

1. Extracts visitor country/region from CloudFront headers
2. Routes the request to your Google Tag Gateway domain
3. Adds x-forwarded-country and x-forwarded-region headers
4. Preserves all original query parameters and cookies

Testing

Verify setup by navigating to: https://yourdomain.com/metrics/healthy

The page should display "ok" if configured correctly.

License

MIT License - see LICENSE file for details.