default.nix

{ config, lib, pkgs, ... }:

with lib;
let
  cfg = config.services.image-classifier;
  script = ./test.py;
in
  {

    options.services.image-classifier.scheduler = {
      enable = mkEnableOption "test";
    };

    config = lib.mkIf cfg.enable {
      systemd.services.hello = {
        after = [ "network-online.target" ];
        wants = [ "network-online.target" ];
        wantedBy = [ "multi-user.target" ];
        serviceConfig = {
          RuntimeDirectory = "helloworld";
          ExecStart = "${pkgs.python3}/bin/python -u ${script} $RUNTIME_DIRECTORY";
        };
      };
    };

  }

test.py

import sys
import os
import time

while True:
    time.sleep(1)
    print(sys.argv)
    print("Hello World")
    print(os.getcwd())
    #print(os.listdir())