Running a python program as a system service on Ubuntu 22

Question

I have such python code, to notice by TG when do my docker containers fall:

import subprocess
import requests
import time

TELEGRAM_BOT_TOKEN = '##############'
CHAT_ID = '##################'


def get_containers():
    cmd = "docker ps -a --format '{{.Names}}'"
    result = subprocess.run(cmd, shell=True, capture_output=True, text=True)
    return result.stdout


def get_containers_status(container_name):
    cmd = "docker inspect --format '{{.State.Health.Status}}' "+container_name+" 2>/dev/null"
    result = subprocess.run(cmd, shell=True, capture_output=True, text=True)
    return result.stdout


def send_telegram_message(message):
    url = f'https://api.telegram.org/bot{TELEGRAM_BOT_TOKEN}/sendMessage'
    data = {'chat_id': CHAT_ID, 'text': message}
    requests.post(url, data=data)


def log_to_journald(message):
    cmd = f"echo '{message}' | systemd-cat -t docker-monitor"
    subprocess.run(cmd, shell=True)

def check_arrays_for_ident(arr1,arr2):
    if len(arr1) == len(arr2):
        for value in arr1:
            if value not in arr2:
                return False

        return True
    else:
        return False

if __name__ == "__main__":
    print("Start")
    
    old_broke_containers = []

    container_dict = {}

    while True:
        
        containers_status = get_containers()
        container_list = containers_status.split()

        broke_containers = []

        
        for container in container_list:
            status = get_containers_status(container)
            container_dict[container] = status
            if status=="unhealthy\n":
                broke_containers.append(container)

        message = "empty"

        if not check_arrays_for_ident(broke_containers, old_broke_containers):
            if 'unhealthy\n' in container_dict.values():
                message = "———————————————————\n"
                message+="⚠️⚠️⚠️Недоступные контейнеры:\n\n"
                message+= "".join(map(lambda item: f'❌ {item[0]}\n', filter(lambda item: item[1] == "unhealthy\n", container_dict.items())))

                message+="———————————————————\n\n"
                message+="Доступные контейнеры:\n\n"
                message+= "".join(map(lambda item: f'✅ {item[0]}\n', filter(lambda item: item[1] == "healthy\n", container_dict.items())))

            print(message)

            send_telegram_message(message)

        container_dict.clear()
        old_broke_containers = broke_containers[:]
        time.sleep(3)

       
        if time.time() % 60 == 0:
            log_to_journald("Status update")

It needs to run all the time and load after reboot of server, so I have decided to make a system service out of it. Here is my .service file in /etc/systemd/system

[Unit]
Description=tg-bot
After=multi-user.target

[Service]
User=root
Group=root
Type=simple
Restart=always
ExecStart=/usr/bin/python3 /custom_scripts/docker_checker.py

[Install]
WantedBy=multi-user.target

Then I did sudo systemctl daemon-reload, sudo systemctl enable bot.service and sudo systemctl start bot.service. In sudo systemctl status bot.service it was written, that service works well, but it did nothing, I didn't get notifications. If I run script in console, everything works well