DOP-C02 Exam Dumps : AWS Certified DevOps Engineer - Professional

Step 1: Understanding Lambda Permissions and AWS Config

The custom AWS Config rule evaluates resources and invokes an AWS Lambda function when a compliance check is triggered. For AWS Config to invoke the Lambda function, it requires permission to do so.

Issue: The Lambda function fails to execute because AWS Config doesn ' t have permission to invoke it.

Action: Modify the resource-based policy of the Lambda function to grant AWS Config permission to invoke the Lambda function.

Why: Without this permission, AWS Config cannot trigger the Lambda function, which is why the evaluation fails.

AWS CodeDeploy natively supports automatic rollback based on CloudWatch alarms . To use this capability, you define an alarm that indicates unhealthy behavior (for example, increasing application error rate) and attach that alarm to the deployment group in CodeDeploy. If the alarm goes into ALARM state during or after a deployment, CodeDeploy automatically rolls back to the last known good revision when auto rollback is enabled.

Option A correctly implements this pattern:

Derive a CloudWatch metric from application logs (e.g., count of error-level log entries or HTTP 5xx responses).

Create a CloudWatch alarm on that metric with appropriate thresholds.

Configure the deployment group to use the alarm as part of its alarm configuration and enable auto rollback .

Option B uses CodeDeploy agent logs, which may not directly reflect true application health and couples rollback logic tightly to deployment internals rather than application behavior. Options C and D implement custom rollback logic with Lambda and EventBridge, which re-create behavior that CodeDeploy already provides natively and add unnecessary operational and code complexity.

Therefore, Option A is the simplest and most aligned with built-in CodeDeploy features for automated rollback based on application errors.

This solution will meet the requirements because it will use a CloudFormation custom resource to execute custom logic during the stack set operation. A custom resource is a resource that you define in your template and that is associated with an AWS Lambda function. The Lambda function runs whenever the custom resource is created, updated, or deleted, and can perform any actions that are supported by the AWS SDK. In this case, the Lambda function can use the GuardDuty API to check whether GuardDuty is already enabled in each target account, and if not, enable it. This way, the DevOps engineer can avoid deploying the stack set to accounts that already have GuardDuty enabled, and prevent failure during the deployment.