Starting a users systemd service via python and dbus

Question

It is possible to use systemd's manager via dbus to control services, e.g: Starting a systemd service via python using this:

import dbus
sysbus = dbus.SystemBus()
systemd1 = sysbus.get_object('org.freedesktop.systemd1',     '/org/freedesktop/systemd1')
manager = dbus.Interface(systemd1, 'org.freedesktop.systemd1.Manager')
job = manager.RestartUnit('test.service', 'fail')

However, systemd can also handle user's service files with the --user flag, e.g.:

systemctl --user start test.service

How can the user's manager be used from dbus (with python)? Replacing dbus.SystemBus() with dbus.Bus() or dbus.SessionBus() did not do the trick, as this gives:

dbus.exceptions.DBusException: org.freedesktop.DBus.Error.Spawn.ChildExited: Process org.freedesktop.systemd1 exited with status 1

Answer 1

dbus.SessionBus() is the correct method to connect to the session bus, as per dbus-python tutorial

Based on the error message shown I suspect some other issue with dbus and/or your session. For example, when attempting to connect without a valid session I get a slightly different exception, org.freedesktop.DBus.Error.NotSupported

I would check systemd logs for further information.