Methods and apparatus for instance host configuration are disclosed. A system includes a plurality of instance hosts configurable for resource instances of a network-accessible service, and control servers to manage remote configuration of the instance hosts. In response to an instance configuration request from a client, a selected control server transmits, to a selected instance host, a sequence of one or more commands. The selected instance host instantiates a remote command executor. The remote command executor initiates configuration operations corresponding to the command sequence, and terminates. The selected control server provides a response to the instance configuration request, based at least in part on results of the operations initiated by the executor.