The Trusted Advisor in your AWS account raises the “Low Utilization Amazon EC2 Instances” alerts. You check the EC2 instances and find that some instances should be stopped as they are no longer used. You want to automate this process so that whenever Trusted Advisor discovers a low utilization EC2 instance, the instance will be stopped and you will get an email notification. Which of the following methods is the most appropriate?

Answer options:

A.Use CloudFormation to create an Amazon Cloudwatch Event. Register the SSM Run Command as its target to shut down the low utilization EC2 instances.
B.Configure Amazon Cloudwatch Event and AWS Lambda to monitor the Low Utilization EC2 Instances Trusted Advisor check. Use the Lambda to stop the instances.
C.Create an AWS Config rule to check the Trusted Advisor Low Utilization warning status. Configure the remediation action that automatically stops the instances.
D.Use CloudFormation to set up a Lambda function that gets the Low Utilization EC2 Instances status in Trusted Advisor and stops the instances. Trigger the Lambda function periodically.

Correct Answer – B
Users can automatically stop EC2 instances that have low utilization recommended by Trusted Advisor with Cloudwatch Events and AWS Lambda. Details please refer to https://github.com/aws/Trusted-Advisor-Tools/tree/master/LowUtilizationEC2Instances.
Option A is incorrect: Because the SSM Run Command should not be registered as the target of the CloudWatch Event. It cannot stop instances or send email notifications.
Option B is CORRECT: Because the Amazon Cloudwatch Event can monitor the Trusted Advisor check and the Lambda function can stop instances and provide customized notifications.
Option C is incorrect: AWS Config may work however you have to maintain a custom rule. You can directly monitor the Trusted Advisor checks through AWS CloudWatch Events. Option B is easier.
Option D is incorrect: Because by using CloudWatch Events, the Lambda function will be triggered whenever there is a status match. You do not need to trigger the function periodically.