AWS recently announced AWS Lambda Web Functions , a new kind of Lambda function that runs your code as a Node.js HTTP server listening on a port, rather than as a handler receiving an event. To tell the two apart, the Lambda functions you already know are now called Event Functions. AWS says Web Functions suit web applications, API backends and other HTTP workloads with many concurrent requests.

Until now, the usual ways to run an API on Lambda have been these:

One function per route behind API Gateway.

The whole app in one function behind an adapter, the Lambdalith.

A function URL in front of one function, with no API Gateway at all.

The adapters made that work by turning every event back into a request your framework understands, but you were left with one request at a time per environment, billing for the time spent waiting on I/O and a 6 MB payload limit, which is why Aidan Steele, AWS Hero, calls the approach "always a hack" .…