A team has implemented a service with AWS API Gateway and Lambda. The service endpoint can save input JSON data to the internal database and S3. After the service has run for several years, some data in the JSON body are no longer used and should not be saved anymore. The backend Lambda has been upgraded to support only the valid JSON values. The original API in API Gateway is still used for some time before all users migrate to the new API. How should the original API be configured so that the Lambda still supports the old request in the backend?

Answer options:

A.In the original API, add a stage for canary deployment to understand how many users are still using the old JSON format before the original API service is completely removed.
B.Configure a mapping template in Integration Request to remove the obsolete data so that the original API requests are transformed to be supported by the new Lambda.
C.In the original API, use a new Lambda as an authorizer so that only the requests with valid JSON data can proceed to hit the backend.
D.In Integration Response of the API, add a mapping template to remove the obsolete data for the backend Lambda to support the old requests.

Correct Answer – B
In this question, the backend Lambda is already upgraded, and the original API is kept for some time. However, Lambda only supports the new requests without obsolete data in the JSON body, which means that a mapping template is needed to map the original requests to the new ones in Integration Request.
Option A is incorrect: Because the canary deployment in stage configuration can be regarded as a deployment strategy, which does not help support the original requests.
Option B is CORRECT: Because a mapping template can transform the request to the proper format. From the original users’ perspective, nothing has changed.
Option C is incorrect: Because old requests will be blocked by the authorizer. This is unacceptable.
Option D is incorrect: Because it should be Integration Request instead of Integration Response to add the mapping template.