You have an application hosted in an AWS Auto Scaling group. This application was created using a Cloudformation template. Now your application has got a surge of users which is decreasing the performance of the application. As per your analysis, a change in the instance type to C3 would resolve the issue. Which of the below option can introduce this change while minimizing downtime for end-users?

Answer options:

A.In the AWS console, copy the old launch configuration, and create a new launch configuration with the C3 instances. Update the Auto Scaling group with the new launch configuration. Auto Scaling will then update the instance type of all running instances.
B.Update the launch configuration in the AWS CloudFormation template with the new C3 instance type. Add an UpdatePolicy attribute to the Auto Scaling group that specifies an AutoScalingRollingUpdate. Run a stack update with the updated template.
C.In the AWS console, update the existing launch configuration with the new C3 instance type and perform a rolling update in the Auto Scaling group.
D.Update the AWS CloudFormation template that contains the launch configuration with the new C3 instance type. Run a stack update with the updated template, and Auto Scaling will then update the instances one at a time with the new instance type.

Answer – B
The cloudformation template should be updated with the new instance type.
The AWS::AutoScaling::AutoScalingGroup resource supports an UpdatePolicy attribute. This is used to define how an Auto Scaling group resource is updated when an update to the CloudFormation stack occurs. A common approach to updating an Auto Scaling group is to perform a rolling update, which is done by specifying the AutoScalingRollingUpdate policy. According to the parameters specified, this retains the same Auto Scaling group and replaces old instances with new ones.
Option A is incorrect because the change should be performed through the CloudFormation template. It is not appropriate to change it directly in the AWS console.
Option C is incorrect because you cannot directly change an existing launch configuration through the AWS console.
Option D is incorrect because we need the AutoScalingRollingUpdate attribute in the CloudFormation template to ensure a rolling update is performed.
For more information on AutoScaling Rolling updates, please refer to the below link:
https://aws.amazon.com/premiumsupport/knowledge-center/auto-scaling-group-rolling-updates/