Question

A retail company runs a production web application behind an Application Load Balancer. The platform team wants to perform blue/green deployments by gradually shifting a percentage of live traffic from the current version (green) to a new version (blue) on the same listener, monitoring error rates before completing the cutover. Both versions are registered in separate target groups. What is the correct way to configure the ALB to shift a controlled percentage of traffic between the two versions?

Accepted Answer

Create a single listener rule with a forward action that references both target groups and assigns weights to each, adjusting the weights incrementally to shift traffic.

Answer

Create two separate listeners on different ports and use Route 53 weighted records to distribute traffic between the listener endpoints.

Answer

Register both versions' instances in a single target group and rely on the ALB round-robin algorithm to distribute traffic proportionally.

Answer

Configure a host-based routing rule that sends a fixed subset of hostnames to the blue target group and the remainder to green.