AWS Certified Solutions Architect – Professional (SAP-C02) — Question 518

A company is running a large containerized workload in the AWS Cloud. The workload consists of approximately 100 different services. The company uses Amazon Elastic Container Service (Amazon ECS) to orchestrate the workload.

Recently the company’s development team started using AWS Fargate instead of Amazon EC2 instances in the ECS cluster. In the past, the workload has come close to running the maximum number of EC2 instances that are available in the account.

The company is worried that the workload could reach the maximum number of ECS tasks that are allowed. A solutions architect must implement a solution that will notify the development team when Fargate reaches 80% of the maximum number of tasks.

What should the solutions architect do to meet this requirement?

Answer options

• A. Use Amazon CloudWatch to monitor the Sample Count statistic for each service in the ECS cluster. Set an alarm for when the math expression sample count/SERVICE_QUOTA(service)*100 is greater than 80. Notify the development team by using Amazon Simple Notification Service (Amazon SNS).
• B. Use Amazon CloudWatch to monitor service quotas that are published under the AWS/Usage metric namespace. Set an alarm for when the math expression metric/SERVICE_QUOTA(metric)*100 is greater than 80. Notify the development team by using Amazon Simple Notification Service (Amazon SNS).
• C. Create an AWS Lambda function to poll detailed metrics from the ECS cluster. When the number of running Fargate tasks is greater than 80, invoke Amazon Simple Email Service (Amazon SES) to notify the development team.
• D. Create an AWS Config rule to evaluate whether the Fargate SERVICE_QUOTA is greater than 80. Use Amazon Simple Email Service (Amazon SES) to notify the development team when the AWS Config rule is not compliant.

Correct answer: B

Explanation

Amazon CloudWatch automatically publishes service usage metrics to the AWS/Usage namespace, allowing users to track usage against service quotas. By setting up a CloudWatch alarm with metric math that divides the usage metric by the SERVICE_QUOTA function, you can dynamically alert the team via Amazon SNS when utilization exceeds 80%. Other options either monitor incorrect metrics (such as individual service sample counts instead of total Fargate task limits) or introduce unnecessary complexity via custom Lambda functions and AWS Config rules.