AWS Serverless Application Model it's a great framework to start building serverless applications. With just a few lines of configuration, you can define the application you want and deploy it. AWS SAM hides all the boilerplate configurations needed when building directly using AWS CloudFormation resources and properties.
While this is great for a quick start, it can become very quickly frustrating when you want to implement slightly more complex functionalities, such as validation, authorization, transformation, etc.
We’ve started a repository with simple SAM templates that shows you how to build either a proxy integration or a custom integration, or how to add validation functionalities directly to your API gateway. Come check it out, and bookmark it for further reference, as we will maintain it with more useful examples: