Chapter 2. Your first Lambda function

In the first chapter you learned how AWS Lambda functions work and how they can be used synchronously (returning a result) or asynchronously (for example, subscribing a function to an event). In the second part of the chapter you learned how a group of functions can be used to build an event-driven application in which the logic is bound to events coming from outside (a client application) or inside (relationships among data).

It’s now time to build your first functions and see how they can be used from a client application using the AWS Lambda interface. The AWS Lambda interface is easy to use with the AWS command-line interface (CLI), or one of the AWS software development kits (SDKs) that can run on a server, in a browser, or in a mobile client.

2.1. Creating a new function

Any good programming book should start with the “Hello World” example. But with AWS Lambda you don’t have standalone applications, but functions that take an input (event) and can optionally provide a result (when called synchronously).

Let’s start with a slightly more complex task: a function that’s looking into the event for a name to “greet” and returns “Hello <name>!” If no name is provided in the event, then the function should return a more generic “Hello World!”

2.2. Writing the function

2.3. Specifying other settings

2.4. Testing the function

2.5. Executing the function through the Lambda API

Summary

Exercise