AWS Edge Functions Kit

Development, testing and deployment of Lambda@Edge and CloudFront functions.

Table of Contents

• Background
• Getting Started
• CloudFront User Config

Background

Amazon CloudFront (CDN) supports two methods of executing server-side code during different stages of a request:

• Lambda@Edge
• CloudFront functions

It's important to know and understand the stages of a CloudFront request. They are:

• Viewer Request
• Origin Request
• Origin Response
• Viewer Response

Each stage supports a single edge function association, whether Lambda@Edge or a CloudFront function.
It is imperative to test these edge functions prior to associating them with your CloudFront distribution.
There are no out-of-the-box, robust strategies that exist today to accomplish this due to the complexity and integration of services that comprise CloudFront.
AWS reccommends "complete integration testing, where your function is associated with a distribution and runs based on a CloudFront event."
This makes sense, but is difficult to achieve. At this time, we are unit testing our functions, using CloudFront request/response event objects.

Getting Started

This project uses docker-compose.

1. docker-compose up -d --build
2. docker-compose exec builder sh
3. npm run build
4. npm run test

CloudFront User Config

The CloudFront user config is located at ./config/cloudfront.yaml in the project.

The CloudFront user config uses the following structure:

distributionId:
  - behavior: { '*', '/api*' }
    lambdaAssociations:
      - functionName: lambda-function-name
        eventType: { viewer-request, viewer-response, origin-request, origin-response }
        filePath: path/to/function/code
        includeBody: { true, false }
    functionAssociations:
      - functionName: cloudfront-function-name
        eventType: { viewer-request, viewer-response }
        filePath: path/to/function/code