What's the target group port for, when using Application Load Balancer + EC2 Container Service

Question

I\'m trying to setup an ALB which listens on port 443, load balancing to ECS Docker containers on random ports, lets say I have 2 container instances of the same task definition

Answer 1

I think what he's referring to is the health checks. If your ELB is listening on port 443 but your target group is set for port 80, then every health check for the target group will attempt a request on port 80 and get redirected to port 443 by the load balancer. This results in a 301 code, which is considered unhealthy. Only 200 codes are supposed to be considered healthy. At that point you either have all unhealthy targets all the time or you add 301 to the list of healthy codes which defeats the whole point in health checks because it will always return a 301 for port 80. You might as well just match the ports.