process management with python: execute service or systemd or init.d script

Question

How to efficiently and correctly manage processes with python. I want to run commands like:

/etc/init.d/daemon stop
service daemon start
systemctl restart daemon

Is there any python module available for this?

Any help will be highly appreciated.

Answer 1

I found a way using systemd dbus interface. Here is the code:

import dbus
import subprocess
import os
import sys
import time

SYSTEMD_BUSNAME = 'org.freedesktop.systemd1'
SYSTEMD_PATH = '/org/freedesktop/systemd1'
SYSTEMD_MANAGER_INTERFACE = 'org.freedesktop.systemd1.Manager'
SYSTEMD_UNIT_INTERFACE = 'org.freedesktop.systemd1.Unit'

bus = dbus.SystemBus()

proxy = bus.get_object('org.freedesktop.PolicyKit1', '/org/freedesktop/PolicyKit1/Authority')
authority = dbus.Interface(proxy, dbus_interface='org.freedesktop.PolicyKit1.Authority')
system_bus_name = bus.get_unique_name()

subject = ('system-bus-name', {'name' : system_bus_name})
action_id = 'org.freedesktop.systemd1.manage-units'
details = {}
flags = 1            # AllowUserInteraction flag
cancellation_id = '' # No cancellation id

result = authority.CheckAuthorization(subject, action_id, details, flags, cancellation_id)

if result[1] != 0:
    sys.exit("Need administrative privilege")

systemd_object = bus.get_object(SYSTEMD_BUSNAME, SYSTEMD_PATH)
systemd_manager = dbus.Interface(systemd_object, SYSTEMD_MANAGER_INTERFACE)

unit = systemd_manager.GetUnit('cups.service')
unit_object = bus.get_object(SYSTEMD_BUSNAME, unit)
#unit_interface = dbus.Interface(unit_object, SYSTEMD_UNIT_INTERFACE)

#unit_interface.Stop('replace')
systemd_manager.StartUnit('cups.service', 'replace')

while list(systemd_manager.ListJobs()):
    time.sleep(2)
    print 'there are pending jobs, lets wait for them to finish.'

prop_unit = dbus.Interface(unit_object, 'org.freedesktop.DBus.Properties')

active_state = prop_unit.Get('org.freedesktop.systemd1.Unit', 'ActiveState')

sub_state = prop_unit.Get('org.freedesktop.systemd1.Unit', 'SubState')

print active_state, sub_state