A company is running a large-scale web application on Amazon EC2 instances behind an Application Load Balancer. They want to implement a blue/green deployment strategy to minimize downtime and risk during updates. The infrastructure is managed using AWS CloudFormation. Which approach requires the LEAST custom scripting and operational overhead?

Use AWS CodeDeploy to manage the blue/green deployment, integrating it with the existing ALB and Auto Scaling groups.

Update the CloudFormation template to create a second Auto Scaling group. Manually update the ALB listener rules to shift traffic.

Use Amazon Route 53 weighted routing to shift traffic between two separate ALBs.

Migrate the application to AWS Elastic Beanstalk and use the 'Swap Environment URLs' feature.