Question

A developer exposes a REST API through Amazon API Gateway that forwards requests to a Lambda function. The Lambda code is being invoked with malformed JSON bodies and missing required query parameters, wasting compute and generating errors. The team wants to reject these bad requests before they reach Lambda, without adding custom validation code. What is the MOST appropriate approach?

Accepted Answer

Enable API Gateway request validation using a JSON Schema model and mark required query string parameters as required in the method request.

Answer

Add a Lambda authorizer that inspects the request body and returns a Deny policy for malformed payloads.

Answer

Configure a mapping template in the integration request to silently drop requests that fail validation.

Answer

Enable AWS WAF on the API stage with a rule that blocks requests containing invalid JSON.