# Running Custom Master Processes

Note

Salt engines are a new feature in 2015.8.0 that let you run custom processes on the Salt master and on Salt minions. Salt engines provide more functionality than `ext_processes` by accepting arguments, and by providing access to Salt config, execution modules, and runners.

In addition to the processes that the Salt master automatically spawns, it is possible to configure it to start additional custom processes.

This is useful if a dedicated process is needed that should run throughout the life of the Salt master. For periodic independent tasks, a scheduled runner may be more appropriate.

Processes started in this way will be restarted if they die and will be killed when the Salt master is shut down.

## Example Configuration

Processes are declared in the master config file with the ext_processes option. Processes will be started in the order they are declared.

    ext_processes:
      - mymodule.TestProcess
      - mymodule.AnotherProcess

## Example Process Class

    # Import python libs
    import time
    import logging
    from multiprocessing import Process

    # Import Salt libs
    from salt.utils.event import SaltEvent

    log = logging.getLogger(__name__)

    class TestProcess(Process):
        def __init__(self, opts):
            Process.__init__(self)
            self.opts = opts

        def run(self):
            self.event = SaltEvent("master", self.opts["sock_dir"])
            i = 0

            while True:
                self.event.fire_event({"iteration": i}, "ext_processes/test{0}")
                time.sleep(60)