service_wrapper 0.0.3

Making services easy

Service Wrapper

A python tool to easily create services running under the os's service management [source code]

Function as a service

Using a simple decorator, make your script a service running under:

• Windows's scm
• linux's systemd (needs additional testing)

Intended to work with PyInstaller (or alternatives) to create an executable that can be registered under scm or systemd.

python main.py still works. Function will block until KeyboardInterrupt is received.

main.py

from service_wrapper.windows import as_service


@as_service(SERVICE_NAME, SERVICE_DISPLAY_NAME, SERVICE_ENTRYPOINT_COMMAND)
def main():
    startup()
    try:
        yield
    finally:
        cleanup()


if __name__ == "__main__":
    main()

NOTES:

• The decorated function should not accept arguments
• startup should be non-blocking (open threads/processes)
• In linux function may be blocking
• For blocking functions. look at Blocking Functions

Blocking functions

---

It is recommended to use a Generator as the decorated function but not required. in linux, a blocking function will behave normally. In order to decorate a blocking function in windows:

from service_wrapper.windows import as_service
from service_wrapper.windows import BlockingService


@as_service(
    SERVICE_NAME,
    SERVICE_DISPLAY_NAME,
    SERVICE_ENTRYPOINT_COMMAND,
    svc_class=BlockingService,
)
def main():
    run_logic()


if __name__ == "__main__":
    main()

NOTES:

• When invoked using scm (PyInstalled and installed as a service), BlockingService will run main() is a separate spawned process.
• SIGINT will be sent to that process the scm stop is called
• svc_class attribute is not supported in linux

Service Tooling

Controls for installing\removing the service are provided using the ServiceTools.

They are to be used externally in scripts to streamline installation\removal etc.

For example, usage in CI with a tool like invoke

from pathlib import Path

from invoke import Context, task

from service_wrapper.windows import get_service
from service_wrapper.windows.service_tools import ServiceTools

service_tools = ServiceTools(get_service(main))

EXECUTABLE_PATH = Path("./dist/svc.exe")


@task()
def build(context: Context) -> None:
    context.run(
        f"pyinstaller "
        f"--onefile "
        f"--name=svc "
        f"main.py"
    )


@task(build)
def install(_: Context) -> None:
    service_tools.install_service(EXECUTABLE_PATH)


@task
def restart(_: Context) -> None:
    service_tools.stop_service()
    service_tools.start_service()