You just joined an IT company and took over the duties from another DevOps engineer to maintain AWS resources. After a while, you have found that a health check timer for an Elastic Load Balancer needs to be updated. The ELB together with Auto scaling configurations were created by a CloudFormation template one year ago. You can find the template in a CodeCommit repository. During the year, it is highly possible that someone has changed some configurations. However, there is no information to record the modification details for the CloudFormation stack. What should you do to update the ELB health check timer?

Answer options:

A.Delete the CloudFormation stack since the changes in the stack are not tracked in git. Rewrite the CloudFormation template with the new health check timer and create a new CloudFormation stack using the new template. Commit the code changes to the CodeCommit repository.
B.Modify the template with the new Elastic Load Balancer health check timer. Update the stack using the new template. Submit the new template to the CodeCommit repository.
C.Use “Detect drift” to understand the changes since the stack was created. Update the template accordingly together with the new health check timer and submit the new code to CodeCommit. Update the stack using the new template.
D.Edit the template properly with the new ELB health check timer. Create a Change Set for the CloudFormation stack using the new template. If the Change Set is ok, execute the Change Set.

Correct Answer – C
Infrastructure as Code is a key concept for AWS DevOps professional exam according to the exam blueprint in https://d1.awsstatic.com/training-and-certification/docs-devops-pro/AWS%20Certified%20DevOps%20Engineer%20Professional_Exam%20Guide_v1.5_FINAL%20(2).pdf. Besides, Infrastructure as Code itself has become a best practice for automating the provisioning of infrastructure services in AWS.
Option A is incorrect: Because the stack does not need to be deleted since the changes can be deployed by updating the stack using a new template.
Option B is incorrect: If the template is only updated with the new ELB health check timer, the stack drift will be lost since it was first created.
Option C is CORRECT: Because “Detect drift” is appropriate for understanding the changes for the resources in the stack. Then all changes are recorded and version-controlled in the CodeCommit repo, which is a best practice for Infrastructure as Code.
Option D is incorrect: Although the usage of Change Set is a best practice, it does not mention saving the template changes to CodeCommit. As a result, the modification is not tracked as code and may get lost. Option C is more accurate than Option
D.