AWS Lambda

AWS Lambda - serverless compute service that automatically manages compute resources. It can run code ("Lambda function") in response to HTTP requests via Amazon API Gateway, among other events. A Lambda function is ready to run as soon as it's triggered.

Useful resources:

https://www.youtube.com/watch?v=fSUEk6iMW88&list=PLzvRQMJ9HDiSQMe68cti8cupI0mzLk1Gc&index=1
https://docs.aws.amazon.com/lambda/latest/dg/nodejs-prog-model-handler.html

Example for nodejs

exports.myHandler = function(event, context, callback) {
   console.log("value1 = " + event.key1);
   console.log("value2 = " + event.key2);  
   callback(null, "some success message");
   // or 
   // callback("some error type"); 
}

Where
myHandler - This is the name of the function AWS Lambda invokes.
context - AWS Lambda uses this parameter to provide details of your Lambda function's execution.

callback(Error error, Object result);

In callback both parameters are optional. To indicate an error, error has to be passed in, not null.