A SysOps Administrator manages a production web application deployed via an AWS CloudForma… — AWS Certified SysOps Administrator - Associate

A SysOps Administrator manages a production web application deployed via an AWS CloudFormation template. The application runs on an Amazon EC2 Auto Scaling group (ASG) behind an Application Load Balancer, with a desired capacity of $4$ instances. The administrator is preparing to update the template to roll out a new AMI using the AutoScalingRollingUpdate policy. The application must maintain its full capacity of $4$ healthy instances throughout the update process to handle peak traffic. Which configuration for the AutoScalingRollingUpdate policy will satisfy this requirement?

A
Set MinInstancesInService to $2$ and MaxBatchSize to $2$ .
B
Set MinInstancesInService to $0$ and MaxBatchSize to $4$ .
Set MinInstancesInService to $4$ and MaxBatchSize to $2$ .Answer
D
Set SuspendProcesses to include Launch and Terminate processes.

Answer

Setting MinInstancesInService to

4

and MaxBatchSize to

2

ensures that AWS CloudFormation launches new instances first to maintain the desired capacity of

4

instances during the rolling update.

The correct configuration requires setting MinInstancesInService to

4

and MaxBatchSize to

2

. This tells AWS CloudFormation that it must keep at least

4

instances running and healthy at all times. Since the group's desired capacity is

4

, CloudFormation will satisfy this by first provisioning a batch of

2

new instances (bringing the total to

6

) before terminating

2

old instances, keeping capacity at or above

4

throughout the rollout.

Step-by-Step Solution

Analyze the capacity requirement.

The application must maintain its desired capacity of

4

healthy instances throughout the update.

To prevent any reduction in capacity during the deployment.

Determine the role of MinInstancesInService.

Setting MinInstancesInService to

4

guarantees that at least

4

instances remain active.

If MinInstancesInService is less than

4

, CloudFormation may terminate instances first, reducing active capacity below the required threshold.

Determine the role of MaxBatchSize.

Setting MaxBatchSize to

2

allows CloudFormation to update instances in batches of

2

. Since

4

instances must remain in service, CloudFormation will launch

2

new instances first before terminating any old ones.

To transition the group to the new AMI incrementally while staying within the minimum capacity constraint.

Key Concept

AWS CloudFormation AutoScalingRollingUpdate UpdatePolicy configuration for maintaining application capacity

Alternative Method

Instead of an in-place rolling update on the same Auto Scaling group, the administrator could perform a blue/green deployment by creating a second Auto Scaling group using the new launch template, validating the new instances, and then updating the Application Load Balancer listener rule to point to the new target group. However, this would require managing additional resources outside the single Auto Scaling group scope.

Estimated Time:1m 30s

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Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Alternative Method

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