You would think so. ;) But I had to jump through some hoops to deal with a few possible cases.

If the nimbus host is defined as an IP, that's usually okay. But if it's defined as a hostname, then it depends on how that hostname resolves locally... If it resolves to 127.0.0.1 the tracker would bind to that address, then you're out of luck because the BT clients on the supervisor nodes will never be able to reach it. The same is true if it binds to another interface that the supervisor nodes can't reach. If the supervisors can't reach the tracker, topology submission will hang forever, since the supervisors won't be able to download the code.

In the end I decided to make it configurable separate from the nimbus host. The default config is 0.0.0.0, meaning it will bind to all interfaces. This seemed like the safest default.