If you want to use the rudder SDK in a lambda function, this will help you build it including any dependencies using docker and the official AmazonLinux image to ensure compatibility.
Simply add whatever logic you want to the index.js file and run the shell scripts in order. It will leave you with a ZIP file you can upload to AWS Lambda.
I've detailed how to setup an AWS API Gateway to use this boilerpalte to ingest an incoming webhook into RudderStack. Check it out here.