How to Create an Alarm for Auto Scaling Group Based on CPU Utilization
Question
The deployment team has recently deployed a new application on the Amazon EC2 instance launched in an Auto Scaling group.
The Operations Team is monitoring the Amazon EC2 instance using Amazon CloudWatch.
Team Lead wants to be notified only when multiple metrics are all in ALARM state.
For cost optimization, Auto scaling groups should scale in based upon CPU utilization. What alarm can be created to meet this requirement?
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D.Correct Answer: B.
A metric alarm watches a single CloudWatch metric which can be used to initiate actions on AWS resources or notify SNS topics.A composite alarm considers the state of multiple metric alarms or composite alarm states which it is part of before going into ALARM mode.
A composite alarm helps to reduce the number of notifications.
But it cannot initiate actions based upon the ALARM state.
Option A is incorrect as a composite alarm would be preferred to be used over a metric alarm to notify.
With Metric alarms, clients will get notifications for every alarm in an ALARM state.
Options C & D are incorrect as composite alarms can only notify SNS topics, it does not take action to initiate a scale-in action for Auto Scaling Group based upon CPU utilization.
For more information on alarms with Amazon CloudWatch, refer to the following URL,
https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/Create_Composite_Alarm.htmlThe requirement is to receive a notification only when multiple metrics are all in ALARM state and to optimize costs, Auto Scaling groups should scale in based on CPU utilization. Therefore, a composite alarm can be created to meet this requirement.
A composite alarm is an alarm that is based on multiple metrics. It is triggered when all the specified metrics are in the ALARM state. So, creating a composite alarm to initiate a scale-in action for Auto Scaling Group based upon CPU utilization and to notify SNS topics will fulfill the requirement.
Option A is incorrect because it only creates a metric alarm to initiate a scale-in action based on CPU utilization and notify SNS topics. It does not fulfill the requirement of receiving a notification only when multiple metrics are in the ALARM state.
Option B is incorrect because it creates a composite alarm to notify SNS topics but does not mention anything about initiating a scale-in action based on CPU utilization.
Option D is also incorrect because it creates a composite alarm and a metric alarm. While the composite alarm meets the requirement, creating a metric alarm to notify SNS topics is not necessary as the composite alarm already notifies SNS topics.
In conclusion, option C is the correct answer as it creates a composite alarm to initiate a scale-in action for Auto Scaling Group based upon CPU utilization and to notify SNS topics.
