Creating a Service

To define a service, simply subclass and fill in the methods to do stuff as the service is started/stopped etc.:

class MyService(Service):

    async def on_start(self) -> None:
        print('Im starting now')

    async def on_started(self) -> None:
        print('Im ready')

    async def on_stop(self) -> None:
        print('Im stopping now')

To start the service, call await service.start():

await service.start()

Or you can use mode.Worker (or a subclass of this) to start your services-based asyncio program from the console:

if __name__ == '__main__':
    import mode
    worker = mode.Worker(
        MyService(),
        loglevel='INFO',
        logfile=None,
        daemon=False,
    )
    worker.execute_from_commandline()

It's a Graph!

Services can start other services, coroutines, and background tasks.

1) Starting other services using add_dependency:

 class MyService(Service):

     def __post_init__(self) -> None:
        self.add_dependency(OtherService(loop=self.loop))

1) Start a list of services using on_init_dependencies:

class MyService(Service):

    def on_init_dependencies(self) -> None:
        return [
            ServiceA(loop=self.loop),
            ServiceB(loop=self.loop),
            ServiceC(loop=self.loop),
        ]

1) Start a future/coroutine (that will be waited on to complete on stop):

 class MyService(Service):

     async def on_start(self) -> None:
         self.add_future(self.my_coro())

     async def my_coro(self) -> None:
         print('Executing coroutine')

1) Start a background task:

class MyService(Service):

    @Service.task
    async def _my_coro(self) -> None:
        print('Executing coroutine')

1) Start a background task that keeps running:

class MyService(Service):

    @Service.task
    async def _my_coro(self) -> None:
        while not self.should_stop:
            # NOTE: self.sleep will wait for one second, or
            #       until service stopped/crashed.
            await self.sleep(1.0)
            print('Background thread waking up')