AWS Certified Sysops Administrator Associate · Free Practice Question Medium
Question 51
A SysOps Administrator deployed an application using AWS CloudFormation. The application runs on Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer (ALB). A new version of the application must be deployed. The update must avoid DNS changes and support rollback.
Which solution should the Administrator use to meet the deployment requirements for application update?
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A
Create a new Amazon Machine Image (AMI) containing the updated code. Create a launch configuration with the AMI. Update the Auto Scaling group to use the new launch configuration.
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B
Modify the CloudFormation template to use an AutoScalingReplacingUpdate policy. Update the stack. Perform a second update with the new release.
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C
Deploy a second CloudFormation stack. Wait for the application to be available. Cut over to the new Application Load Balancer.
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D
Configure the Auto Scaling group to use lifecycle hooks. Deploy new instances with the new application version. Complete the lifecycle hook action once healthy.
Reveal correct answer
Correct answer: B
Explanation
To specify how AWS CloudFormation handles replacement updates for an Auto Scaling group, use the AutoScalingReplacingUpdate policy. This policy enables you to specify whether AWS CloudFormation replaces an Auto Scaling group with a new one or replaces only the instances in the Auto Scaling group.
CORRECT: "Modify the CloudFormation template to use an AutoScalingReplacingUpdate policy. Update the stack. Perform a second update with the new release" is the correct answer.
INCORRECT: "Configure the Auto Scaling group to use lifecycle hooks. Deploy new instances with the new application version. Complete the lifecycle hook action once healthy" is incorrect. You should use AWS CloudFormation to update the stack rather than updating the resources directly.
INCORRECT: "Deploy a second CloudFormation stack. Wait for the application to be available. Cut over to the new Application Load Balancer" is incorrect. This method would require a DNS update. It hasn’t been mentioned in the question but presumably there would be an Amazon Route 53 Alias record or similar pointing to the existing ALB. This would need to be updated to point to the new ALB.
INCORRECT: "Create a new Amazon Machine Image (AMI) containing the updated code. Create a launch configuration with the AMI. Update the Auto Scaling group to use the new launch configuration" is incorrect. This method means you would cause issues with stack drift as you are updating the resources directly rather than through CloudFormation.
References:
https://aws.amazon.com/premiumsupport/knowledge-center/auto-scaling-group-rolling-updates/
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Discussion
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