Question

A CloudOps engineer manages a single Application Load Balancer that fronts three microservices running on separate Amazon ECS services. Requests to /api/orders must reach the orders service, /api/inventory must reach the inventory service, and all other requests must reach a default web frontend service. All three services are already registered in separate target groups. What is the correct way to configure the ALB to achieve this routing?

Accepted Answer

Create listener rules on the HTTPS listener that use path-based conditions (/api/orders*, /api/inventory*) to forward to the respective target groups, and set the default action to forward to the web frontend target group.

Answer

Create three separate Application Load Balancers, one per target group, and use Route 53 weighted records to distribute traffic based on the request path.

Answer

Configure a single listener rule with host-based conditions mapping each hostname to a target group, then rely on the security groups to filter requests by path.

Answer

Attach all three target groups to the listener's default action as a weighted forward action so the ALB balances requests across services.