Why would Storm UI running on ECS give me a jetty 404 error?

I'm running a storm (v1.2.1) container with the command:

storm,ui

on ECS. The UI container runs on the same task as the zookeeper and nimbus. I've deployed the task on FARGATE as a service which has service discovery enabled.

The containers are all running fine with no errors in the logs. I've configured the task definition to map port 8080 so that I can access the storm UI.

However, when I try, all I get is a jetty 404 page. This tells me that I'm hitting the container, but somehow the storm ui is not there. I suppose an alternative is that I'm hitting a different container, but I'm not sure how that's possible.

This is the error I see:

Why is storm UI giving me a 404?

I finally got access to the container logs using ECS ExecCommand and the error was that it couldn't bind to the port.

I modified the Storm UI container to include the following command flag:

-c ui.port=[not 8080]

and mapped the new port from the container to the host. The UI worked, then.