webui_url entry in Mesos state JSON is optional, one can try the luck with
hostname (which is also optional).
However, if both of the above entries are missing from Mesos state, is there any other way to reliably discover where Marathon API server is listening?
Furthermore, if a Marathon instance is migrated to another location, Mesos
webui_url seems to retain the old, stale value. This looks like a bug? Is there any workaround?