You have a web application composed of an Auto Scaling group of web servers behind a load balancer, and create a new AMI for each application version for deployment. You have a new version to release, and you want to use the Blue-Green deployment technique to migrate users over in a controlled manner while the size of the fleet remains constant over a period of 6 hours, to ensure that the new version is performing well. What option should you choose to enable this technique while being able to roll back easily? Choose 2 answers from the options given below. Each answer presents part of the solution

Answer options:

A.Create an Auto Scaling launch configuration with the new AMI to use the new launch configuration and to register instances with the new load balancer
B.Create an Auto Scaling launch configuration with the new AMI to use the new launch configuration and to register instances with the existing load balancer
C.Use Amazon Route53 weighted Round Robin to vary the proportion of requests sent to the load balancers.
D.Configure Elastic Load Balancing to vary the proportion of requests sent to instances running the two application versions.

Answer – A and C
The AWS documentation gives this example of a Blue Green deployment
You can shift traffic all at once or you can do a weighted distribution. With Amazon Route 53, you can define a percentage of traffic to go to the green environment and gradually update the weights until the green environment carries the full production traffic. A weighted distribution provides the ability to perform canary analysis where a small percentage of production traffic is introduced to a new environment. You can test the new code and monitor for errors, limiting the blast radius if any issues are encountered. It also allows the green environment to scale out to support the full production load if you’re using Elastic Load Balancing, for example
For more information on Blue Green deployments, please refer to the below link:
https://d0.awsstatic.com/whitepapers/AWS_Blue_Green_Deployments.pdf