AWS Certified DevOps Engineer – Professional — Question 132
A retail company wants to use AWS Elastic Beanstalk to host its online sales website running on Java. Since this will be the production website the CTO has the following requirements for the deployment strategy:
• Zero downtime. While the deployment is ongoing the current Amazon EC2 instances in service should remain in service. No deployment or any other action should be performed on the EC2 instances because they serve production traffic.
• A new fleet of instances should be provisioned for deploying the new application version.
• Once the new application version is deployed successfully in the new fleet of instances, the new instances should be placed in service and the old ones should be removed.
• The rollback should be as easy as possible. If the new fleet of instances fails to deploy the new application version, they should be terminated and the current instances should continue serving traffic as normal.
• The resources within the environment (EC2 Auto Scaling group, Elastic Load Balancing, Elastic Beanstalk DNS CNAME) should remain the same and no DNS change should be made.
Which deployment strategy will meet the requirements?
Answer options
- A. Use rolling deployments with a fixed amount of one instance at a time and set the healthy threshold to OK.
- B. Use rolling deployments with additional batch with a fixed amount of one instance at a time and set the healthy threshold to OK.
- C. Launch a new environment and deploy the new application version there, then perform a CNAME swap between environments.
- D. Use immutable environment updates to meet all the necessary requirements.
Correct answer: D
Explanation
The correct answer is D, as immutable environment updates create a new set of instances for the new application version without affecting the existing ones, ensuring zero downtime and easy rollback if needed. Options A and B do not guarantee zero downtime as they take instances out of service during the update, while option C involves a DNS change which is against the requirements.