This will probably not work with the MesosScheduler now unless you make that pass a hostPort too. Maybe you can add code there that binds to a port. By the way, one confusing thing is that the ActorSystem you create for the StandaloneSchedulerBackend, to talk to the standalone master, is *not* the same as the one that we create for RPCs to the job's master (BlockManagerMaster, etc). Will they use the same port?