Python program as service

How to create a Windows Service in Python

Have you ever had the need of writing a Python script that could run in background as a Windows Service? In this post, you will learn how to do it in less than 10 minutes, no jokes.

I will skip all the introduction about Windows Services, how convenient they could be, how much could be appreciated the fact that they can be run in background even when the user is logged off etc… I mean, if you can code in Python and you use Windows I bet you already know what a Windows Service is, don’t you?

So, first of all, let’s start by installing the Python for Windows extensions:

c:test> pip install pywin32 

Once you have done it, let’s write this base class, your Windows service will be a subclass of this base class.

''' SMWinservice by Davide Mastromatteo Base class to create winservice in Python ----------------------------------------- Instructions: 1. Just create a new class that inherits from this base class 2. Define into the new class the variables _svc_name_ = "nameOfWinservice" _svc_display_name_ = "name of the Winservice that will be displayed in scm" _svc_description_ = "description of the Winservice that will be displayed in scm" 3. Override the three main methods: def start(self) : if you need to do something at the service initialization. A good idea is to put here the inizialization of the running condition def stop(self) : if you need to do something just before the service is stopped. A good idea is to put here the invalidation of the running condition def main(self) : your actual run loop. Just create a loop based on your running condition 4. Define the entry point of your module calling the method "parse_command_line" of the new class 5. Enjoy ''' import socket import win32serviceutil import servicemanager import win32event import win32service class SMWinservice(win32serviceutil.ServiceFramework): '''Base class to create winservice in Python''' _svc_name_ = 'pythonService' _svc_display_name_ = 'Python Service' _svc_description_ = 'Python Service Description' @classmethod def parse_command_line(cls): ''' ClassMethod to parse the command line ''' win32serviceutil.HandleCommandLine(cls) def __init__(self, args): ''' Constructor of the winservice ''' win32serviceutil.ServiceFramework.__init__(self, args) self.hWaitStop = win32event.CreateEvent(None, 0, 0, None) socket.setdefaulttimeout(60) def SvcStop(self): ''' Called when the service is asked to stop ''' self.stop() self.ReportServiceStatus(win32service.SERVICE_STOP_PENDING) win32event.SetEvent(self.hWaitStop) def SvcDoRun(self): ''' Called when the service is asked to start ''' self.start() servicemanager.LogMsg(servicemanager.EVENTLOG_INFORMATION_TYPE, servicemanager.PYS_SERVICE_STARTED, (self._svc_name_, '')) self.main() def start(self): ''' Override to add logic before the start eg. running condition ''' pass def stop(self): ''' Override to add logic before the stop eg. invalidating running condition ''' pass def main(self): ''' Main class to be ovverridden to add logic ''' pass # entry point of the module: copy and paste into the new module # ensuring you are calling the "parse_command_line" of the new created class if __name__ == '__main__': SMWinservice.parse_command_line() 

Let’s examine the class we have just introduced a little.

def SvcDoRun(self): it’s the method that will be called when the service is requested to start.

def SvcStop(self): it’s the method that will be called when the service is requested to stop.

def start(self): it’s a method that you will be asked to override if you need to do something when the service is starting (before started)

def stop(self): it’s the method that you will be asked to override if you need to do something when the service is stopping (before stopped)

def main(self): it’s the method that will contain the logic of your script, usually in a loop that keeps it alive until the service is stopped.

def parse_command_line(cls): it’s the method that handles the command line interface that you can use to install and update your windows service

Can you see how easy it is with pywin32 to interface with the system to create a Windows Service? The last mention is for the following variables:

svc_name = "PythonCornerExample" svc_display_name = "Python Corner's Winservice Example" svc_description = "That's a great winservice! :)" 

These are just three variables that contain the name of the service, the “friendly name” that will be used by Windows to display the name on the mmc console and a short description of your service.

As always, enough talk, let’s code something useful!

Let’s pretend that we want to create a Winservice that, when started, creates a random file on our C: drive every 5 seconds.

What? Do you think it is stupid? Well, install it on your boss PC, set the destination folder as its user’s desktop and you will change your mind. 🙂

However, how can you achieve this result? Super easy.

• Subclass the SMWinservice class we have just met.
• On the new class, override the three variables _svc_name_, _svc_display_name_ and _svc_description_.
• Override the “start” method to set the running condition. Setting a boolean variable will be enough for that.
• Override the “stop” method to invalidate the running condition when the service is requested to be stopped.
• Override the “main” method to add the logic of creating a random file every 5 seconds
• Add the call at the “parse_command_line” function to handle the command line interface.

The result should be something like this:

import time import random from pathlib import Path from SMWinservice import SMWinservice class PythonCornerExample(SMWinservice): _svc_name_ = "PythonCornerExample" _svc_display_name_ = "Python Corner's Winservice Example" _svc_description_ = "That's a great winservice! :)" def start(self): self.isrunning = True def stop(self): self.isrunning = False def main(self): i = 0 while self.isrunning: random.seed() x = random.randint(1, 1000000) Path(f'c:x>.txt').touch() time.sleep(5) if __name__ == '__main__': PythonCornerExample.parse_command_line() 

That’s it! Now it’s time to install our newly created winservice. Just open a command prompt, navigate to your script directory and install the service with the command:

C:test> python PythonCornerExample.py install Installing service PythonCornerExample Service installed 

In the future, if you want to change the code of your service, just modify it and reinstall the service with

C:test> python PythonCornerExample.py update Changing service configuration Service updated 

Now, open the “Services” msc snap in

locate your new PythonCornerExample winservice, and right click and choose properties. Here you can start your service and configure it at your will.

Now try to start your service and go to see your C: folder contents.

Can you see all these files being created to your C: folder? Yeah, that’s working!

But now it’s time to stop it! 🙂 You can do it from the previous windows or just by using the command line

C:test> net stop PythonCornerExample Il servizio Python Corner's Winservice Example sta per essere arrestato.. Servizio Python Corner's Winservice Example arrestato. 

If something goes wrong…

There are a couple of known problems that can happen writing Windows Services in Python. If you have successfully installed the service but starting it you get an error, follow this iter to troubleshoot your service:

• Check if Python is in your PATH variable. It MUST be there. To check this, just open a command prompt and try starting the python interpreter by typing “python”. If it starts, you are ok.
• Be sure to have the file C:\Program Files\Python36\Lib\site-packages\win32\pywintypes36.dll (please note that “36” is the version of your Python installation). If you don’t have this file, take it from C:\Program Files\Python36\Lib\site-packages\pywin32_system32\pywintypes36.dll and copy it into C:\Program Files\Python36\Lib\site-packages\win32

If you still have problems, try executing your Python script in debug mode. To try this with our previous example, open a terminal, navigate to the directory where the script resides and type

c:test> python PythonCornerExample.py debug 

Ok, that’s all for today, this was just a brief introduction to developing Windows Services with Python. Try it by yourself and … happy coding!

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Запуск Python скрипта в виде службы через systemctl/systemd

Есть несколько способов запуска вашей программы в качестве фоновой службы в Linux, таких как crontab, .bashrc и т. д., но сегодня будет разговор о systemd. Изначально я искал способ запустить свой скрипт на Python в качестве фоновой службы, поэтому даже если сервер по какой-то причине перезагрузится, мой скрипт все равно должен работать в фоновом режиме, после небольшого ресерча и я обнаружил, что systemd позволяет мне это сделать. Давайте начнем.

Настройки далее будут производиться на машине с Ubuntu 20.04.

Почти все версии Linux поставляются с systemd из коробки, но если у вас его нет, вы можете просто запустить следующую команду:

sudo apt install -y systemd 

Примечание. Флаг -y означает быструю установку пакетов и зависимостей.

Чтобы проверить, какая версия systemd у вас установлена, просто выполните команду:

Создайте файл python с любым именем. Я назову свой скрипт именем test.py.

import time from datetime import datetime while True: with open("timestamp.txt", "a") as f: f.write("Текущая временная метка: " + str(datetime.now())) f.close() time.sleep(10) 

Приведенный выше скрипт будет записывать текущую метку времени в файл каждые 10 секунд. Теперь напишем сервис.

sudo nano /etc/systemd/system/test.service 

(имя службы, которая тестируется в этом случае)

[Unit] Description=My test service After=multi-user.target [Service] User=deepak Group=admin Type=simple Restart=always ExecStart=/usr/bin/python3 /home//test.py [Install] WantedBy=multi-user.target 

Замените имя пользователя в вашей ОС, где написано . Флаг ExecStart принимает команду, которую вы хотите запустить. Таким образом, в основном первый аргумент — это путь к python (в моем случае это python3), а второй аргумент — это путь к скрипту, который необходимо выполнить. Флаг перезапуска всегда установлен, потому что я хочу перезапустить свою службу, если сервер будет перезапущен.

Здесь мы определили User=deepak и Group=admin, чтобы убедиться, что скрипт будет выполняться только от имени пользователя deepak, входящего в группу admin.

Теперь нам нужно перезагрузить демон.

sudo systemctl daemon-reload 

Давайте включим наш сервис, чтобы он не отключался при перезагрузке сервера.

sudo systemctl enable test.service 

А теперь давайте запустим наш сервис.

sudo systemctl start test.service 

Теперь наш сервис работает.

Примечание. Файл будет записан в корневой каталог (/), потому что программа запишет путь с точки зрения systemd. Чтобы изменить это, просто отредактируйте путь к файлу. Например:

import time from datetime import datetime path_to_file = "введите желаемый путь к файлу" while True: with open(path_to_file, "a") as f: f.write("Текущая временная метка: " + str(datetime.now())) f.close() time.sleep(10) 

Есть несколько команд, которые вы можете выполнить для запуска, остановки, перезапуска и проверки состояния.

sudo systemctl stop name_of_your_service 

sudo systemctl restart name_of_your_service 

sudo systemctl status name_of_your_service 

Это было очень поверхностное знакомство с systemd, предназначенное для новичков, которые хотят начать писать свои собственные systemd службы для python.

ПРИМЕЧАНИЕ. Это относится не только к сценариям Python. Вы можете запустить любую программу с ним, независимо от языка программирования, на котором написана ваша программа.

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