pystemd 0.2.0

A systemd binding for python

This library allows you to talk to systemd over dbus from python, without actually thinking that you are talking to systemd over dbus. This allows you to programmatically start/stop/restart/kill and verify services status from systemd point of view, avoiding executing subprocess.Popen(['systemctl', ... and then parsing the output to know the result.

Show don’t tell

In software as in screenwriting, its better to show how things work instead of tell. So this is how you would use the library from a interactive shell.

In [1]: from pystemd.systemd1 import Unit
In [2]: unit = Unit(b'postfix.service')
In [3]: unit.load()

Note: you need to call unit.load() because by default Unit will not load the unit information as that would require do some IO. You can auto load the unit by Unit(b'postfix.service', _autoload=True)

Once the unit is loaded, you can interact with it, you can do by accessing its systemd’s interfaces:

In [4]: unit.Unit.ActiveState
Out[4]: b'active'

In [5]: unit.Unit.StopWhenUnneeded
Out[5]: False

In [6]: unit.Unit.Stop(b'replace') # require privilege account
Out[6]: b'/org/freedesktop/systemd1/job/6601531'

In [7]: unit.Unit.ActiveState
Out[7]: b'inactive'

In [8]: unit.Unit.Start(b'replace') # require privilege account
Out[8]: b'/org/freedesktop/systemd1/job/6601532'

In [9]: unit.Unit.ActiveState
Out[9]: b'active'

In [10]: unit.Service.GetProcesses()
Out[10]:
[(b'/system.slice/postfix.service',
    1754222,
    b'/usr/libexec/postfix/master -w'),
 (b'/system.slice/postfix.service', 1754224, b'pickup -l -t fifo -u'),
 (b'/system.slice/postfix.service', 1754225, b'qmgr -l -t fifo -u')]

In [11]: unit.Service.MainPID
Out[11]: 1754222

The systemd1.Unit class provides shortcuts for the interfaces in the systemd namespace, as you se above, we have Service (org.freedesktop.systemd1.Service) and Unit (org.freedesktop.systemd1.Unit). Others can be found in unit._interfaces as:

In [12]: unit._interfaces
Out[12]:
{'org.freedesktop.DBus.Introspectable': <org.freedesktop.DBus.Introspectable of /org/freedesktop/systemd1/unit/postfix_2eservice>,
 'org.freedesktop.DBus.Peer': <org.freedesktop.DBus.Peer of /org/freedesktop/systemd1/unit/postfix_2eservice>,
 'org.freedesktop.DBus.Properties': <org.freedesktop.DBus.Properties of /org/freedesktop/systemd1/unit/postfix_2eservice>,
 'org.freedesktop.systemd1.Service': <org.freedesktop.systemd1.Service of /org/freedesktop/systemd1/unit/postfix_2eservice>,
 'org.freedesktop.systemd1.Unit': <org.freedesktop.systemd1.Unit of /org/freedesktop/systemd1/unit/postfix_2eservice>}

 In [13]: unit.Service
 Out[13]: <org.freedesktop.systemd1.Service of /org/freedesktop/systemd1/unit/postfix_2eservice>

Each interface has methods and properties, that can access directly as unit.Service.MainPID, the list of properties and methods is in .properties and .methods of each interface.

Alongside the systemd1.Unit, we also have a systemd1.Manager, that allows you to interact with systemd manager.

In [14]: from pystemd.systemd1 import Manager

In [15]: manager = Manager()

In [16]: manager.load()

In [17]: manager.Manager.ListUnitFiles()
Out[17]:
...
(b'/usr/lib/systemd/system/rhel-domainname.service', b'disabled'),
 (b'/usr/lib/systemd/system/fstrim.timer', b'disabled'),
 (b'/usr/lib/systemd/system/getty.target', b'static'),
 (b'/usr/lib/systemd/system/systemd-user-sessions.service', b'static'),
...

In [18]: manager.Manager.Architecture
Out[18]: b'x86-64'

In [19]: manager.Manager.Virtualization
Out[19]: b'kvm'

Extras:

as part of the code we include pystemd.run, the spiritual port of systemd-run to python. example of usage:

# run this as root
>>> import pystemd.run, sys
>>> pystemd.run(
    [b'/usr/bin/psql', b'postgres'],
    machine=b'db1',
    user=b'postgres',
    wait=True,
    pty=True,
    stdin=sys.stdin, stdout=sys.stdout,
    env={b'PGTZ': b'UTC'}
)

will open a postgres interactive prompt in a local nspawn-machine.

Install

So you like what you see, the simplest way to install is by:

$ pip install pystemd

you’ll need to have:

• Python headers: Just use your distro’s package (e.g. python-dev).

• systemd headers: Chances are you already have this, normally is called libsystemd-dev on or systemd-devel, version needs to be at least v221.

• systemd library: check if pkg-config --cflags --libs libsystemd returns -lsystemd if not you can install normally install systemd-libs or libsystemd depending on your distribution, version needs to be at least v221.

• gcc: or any compiler that setup.py will accept.

if you want to install from source then after you clone this repo you need to

$ pip install -r requirements.txt # get six
$ python setup.py install # prefer python3

but in adition to previous requirementrs yoiu’ll need:

• setuptools: Just use your distro’s package (e.g. python-setuptools).

• Six library: for python 2 and 3 compatibility (installed by requirements).

• Cython: at least version 0.21a1, just pip install it or use the official installation guide from cython homepage to get latest http://cython.readthedocs.io/en/latest/src/quickstart/install.html.

License

pystemd is BSD-licensed. We also provide an additional patent grant.