What is the MOST cost-effective way to solve the deployment issue?

A company has deployed an application on AWS Elastic Beanstalk. The company has configured the Auto Scaling group that is associated with the Elastic Beanstalk environment to have five Amazon EC2

instances. If the capacity is fewer than four EC2 instances during the deployment, application performance degrades. The company is using the all-at-once deployment policy.

What is the MOST cost-effective way to solve the deployment issue?
A . Change the Auto Scaling group to six desired instances.
B . Change the deployment policy to traffic splitting. Specify an evaluation time of 1 hour.
C . Change the deployment policy to rolling with additional batch. Specify a batch size of 1.
D . Change the deployment policy to rolling. Specify a batch size of 2.

View Answer

Answer: C

Explanation:

This solution will solve the deployment issue by deploying the new version of the application to one new EC2 instance at a time, while keeping the old version running on the existing instances. This way, there will always be at least four instances serving traffic during the deployment, and no downtime or performance degradation will occur. Option A is not optimal because it will increase the cost of running the Elastic Beanstalk environment without solving the deployment issue. Option B is not optimal because it will split the traffic between two versions of the application, which may cause inconsistency and confusion for the customers. Option D is not optimal because it will deploy the new version of the application to two existing instances at a time, which may reduce the capacity below four instances during the deployment.

Reference: AWS Elastic Beanstalk Deployment Policies