CloudFront Functions - AWS Serverless

2.1 What are CloudFront Functions?

CloudFront Functions enables developers to create functions that are executed in response to CloudFront events, such as viewer requests and origin responses. These functions can manipulate HTTP requests and responses in a fast and cost-effective manner.

2.2 CloudFront Events

CloudFront Functions can be triggered by the following events:

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

2.3 Pricing

CloudFront Functions are billed based on the number of invocations. This makes it a cost-effective choice for high-volume applications.

CloudFront Functions can be utilized for various purposes, including:

1. Customizing HTTP headers for security and caching.
2. Implementing access controls based on user authentication.
3. URL rewriting and redirection.
4. Content filtering based on request attributes.

4.1 Creating a CloudFront Function

Follow these steps to create your first CloudFront Function:

1. Log in to the AWS Management Console.
2. Navigate to the CloudFront service.
3. Select "Functions" from the left menu.
4. Click on "Create Function".
5. Enter a name and description for the function.
6. Write your JavaScript code in the editor provided.

4.2 Sample Code

The following code snippet demonstrates a simple CloudFront Function that adds a custom header:

function handler(event) {
    var request = event.request;
    request.headers['x-custom-header'] = { value: 'MyHeaderValue' };
    return request;
}
                

To ensure optimal performance and maintainability, consider the following best practices:

• Keep functions lightweight to reduce latency.
• Thoroughly test functions in a development environment.
• Use logging to monitor function behavior.
• Implement version control for your functions.