CloudFront Functions, Amazon Web Service’s (AWS) new serverless scripting platform for running lightweight JavaScript code at the edge, is now generally available.
Amazon CloudFront provides customers with the ability to deliver content, such as data, videos, and APIs, securely with low latency and high speed.
To help ease complex and compute-heavy operations and customizations, AWS introduced Lambda@Edge functionality as part of Amazon CloudFront in 2017. Due to faster processing power in data centers, Lambda@Edge functions are typically executed from regional data center cache instead of edge locations.
“When you’re streaming video or audio, you can use Lambda@Edge to create and serve the right segments on-the-fly reducing the need for origin scalability,” explained Amazon.
CloudFront's second category of use cases involves handling simple HTTP(S) request/ response manipulations via short-lived functions.
The new CloudFront Functions from AWS offer the performance and speed required to process millions of requests per second. A process-based isolation model combined with specific network and file system access restrictions enables scalability. This is in stark contrast to Lamda@Edge, which relies on virtual machine-based (VM-based) isolation.
According to AWS, CloudFront Functions are best-suited for lightweight web request processing, including cache-key manipulations and normalization; URL rewrites and redirects; HTTP header manipulation; access authorization; and more.
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CloudFront Functions, like Lambda@Edge, respond to events generated by CloudFront. In particular, CloudFront Functions can be triggered upon receiving a viewer request or delivering a viewer response.
“Lambda@Edge can also be triggered before CloudFront forwards the request to the origin (origin request) and after CloudFront receives the response from the origin (origin response). You can use CloudFront Functions and Lambda@Edge together, depending on whether you need to manipulate content before, or after, being cached,” said Amazon.
Using Lambda@Edge before or after CloudFront caches content is an option if you need certain features of Lambda@Edge that aren't available in CloudFront Functions.
