AWS Certified DevOps Engineer – Professional — Question 44

A company is using AWS CodePipeline to automate its release pipeline. AWS CodeDeploy is being used in the pipeline to deploy an application to Amazon ECS using the blue/green deployment model. The company wants to implement scripts to test the green version of the application before shifting traffic. These scripts will complete in 5 minutes or less. If errors are discovered during these tests, the application must be rolled back.
Which strategy will meet these requirements?

Answer options

• A. Add a stage to the CodePipeline pipeline between the source and deploy stages. Use AWS CodeBuild to create an execution environment and build commands in the buildspec file to invoke test scripts. If errors are found, use the aws deploy stop-deployment command to stop the deployment.
• B. Add a stage to the CodePipeline pipeline between the source and deploy stages. Use this stage to execute an AWS Lambda function that will run the test scripts. If errors are found, use the aws deploy stop-deployment command to stop the deployment.
• C. Add a hooks section to the CodeDeploy AppSpec file. Use the AfterAllowTestTraffic lifecycle event to invoke an AWS Lambda function to run the test scripts. If errors are found, exit the Lambda function with an error to trigger rollback.
• D. Add a hooks section to the CodeDeploy AppSpec file. Use the AfterAllowTraffic lifecycle event to invoke the test scripts. If errors are found, use the aws deploy stop-deployment CLI command to stop the deployment.

Correct answer: C

Explanation

The correct answer is C because it uses the AfterAllowTestTraffic event to run tests after the new version has been allowed to receive test traffic, ensuring that any rollback can be executed if errors occur. Options A and B test before the deployment, which does not align with the blue/green strategy's requirements for testing the 'green' version. Option D triggers tests after traffic is allowed, but it does not specify a rollback mechanism linked to errors in the testing phase.