We're considering the design for how a mongod with an embedded router enters into a sharded cluster. It's possible that we won't need to have the process explicitly accept a configdbs argument, even if it's in embedded router mode, if we decide that the router-layer either needs to sit idle until the shard-layer is entered into the cluster, or that the router can learn the configdb directly if we're a config shard. If this is the case, remove configdbs from mongod.