You have a serverless application with AWS Lambda. This application has Lambda as a backend and has its data stored in DynamoDB. This application is very latency-sensitive. How could you alert your team if the application gets high latency in any of its components?

Answer options:

A.Import the time library in the Lambda code. Calculate how much time it takes the Lambda to finish operations in DynamoDB, deploy these logs to Cloudwatch and create an alarm if the time in the logs is high.
B.Enable X-Ray tracing on Lambda, use the AWS SDK inside Lambda code to monitor DynamoDB API calls in X-Ray, send this information to CloudWatch, and create a metric that triggers an SNS alert if the response times get too high.
C.Enable X-Ray tracing on Lambda, use the AWS SDK inside Lambda code to monitor DynamoDB API calls in X-Ray, send this information to CloudTrail, and create a metric that triggers an SNS alert if the response times get too high.
D.Enable X-Ray in Lambda and DynamoDB. Create a Lambda that will retrieve the info from X-Ray every minute. Send this information to CloudWatch, create a metric that triggers an SNS alert if the response times get too high.

Correct Answer: B
Option A is incorrect because this option considers how long it takes Lambda to establish a connection, perform operations in DynamoDB and return a response, in this question we only want to know how long it takes to connect with DynamoDB. Additionally, more factors can affect the performance of the Lambda, for instance, cold starts, code optimization, or CPU memory.
Option B is CORRECT because AWS X-Ray allows you to record every call to the other AWS service like DynamoDB and trace the latency for AWS services. Mixing X-Ray with CloudWatch is a very good choice to get alarms if the latency becomes high.
Option C is incorrect because with AWS CloudTrail you can track the API requests made by IAM users or services, Cloudtrail is not used to send alerts or to process logs.
Option D is incorrect because until now, it is not possible to enable AWS X-Ray in DynamoDB. You can only track the traces generated by calls to DynamoDB in Lambda with the AWS SDK.