AWS Certified DevOps Engineer – Professional — Question 19

An application runs on Amazon EC2 instances behind an Application Load Balancer (ALB). A DevOps Engineer is using AWS CodeDeploy to release a new version. The deployment fails during the AllowTraffic lifecycle event, but a cause for the failure is not indicated in the deployment logs.
What would cause this?

Answer options

• A. The appspec.yml file contains an invalid script to execute in the AllowTraffic lifecycle hook.
• B. The user who initiated the deployment does not have the necessary permissions to interact with the ALB.
• C. The health checks specified for the ALB target group are misconfigured.
• D. The CodeDeploy agent was not installed in the EC2 instances that are part of the ALB target group.

Correct answer: C

Explanation

The correct answer is C because if the health checks for the ALB target group are misconfigured, the ALB may mark the instances as unhealthy, causing the deployment to fail during the AllowTraffic event. Option A is incorrect as errors in the appspec.yml would typically show in the logs, while option B is not relevant since it pertains to permissions, which don't directly affect traffic allowance. Option D is also incorrect because if the CodeDeploy agent were not installed, the deployment would not even initiate.