python - 如何从 Python 获取失败服务的 systemctl 结果？

Question

如果 systemd 服务单元处于故障状态，systemctl status 会显示这一事实:

    # systemctl status myservice
    ● myservice.service - Important Crash Prone service (myservice)
       Loaded: loaded (/etc/systemd/system/myservice.service; enabled; vendor preset: disabled)
       Active: failed (Result: start-limit) since Tue 2017-08-22 20:04:13 UTC; 3s ago
      Process: 31108 ExecStart=/bin/myservice (code=dumped, signal=ABRT)
     Main PID: 31108 (code=dumped, signal=ABRT)

我想让一个 Python 程序获取“Result: start-limit”字段，而无需 fork systemctl 并尝试解析输出。其他字段(例如 Loaded、Active)可从 Python dbus 库获取。

例如，以下代码获取 ActiveState 属性，该属性由 systemctl 在“Active:”(上面输出中的单词“failed”)之后显示。

from dbus import Interface, SystemBus, SessionBus
bus = SystemBus()
systemd = bus.get_object('org.freedesktop.systemd1',
                         '/org/freedesktop/systemd1')

manager = Interface(systemd, dbus_interface='org.freedesktop.systemd1.Manager')

myservice_unit = manager.LoadUnit('myservice.service')

myservice_proxy = bus.get_object('org.freedesktop.systemd1', str(myservice_unit))

myservice = Interface(myservice_proxy, 
dbus_interface='org.freedesktop.systemd1.Unit')

prop = 'ActiveState'
value = myservice_proxy.Get('org.freedesktop.systemd1.Unit',
                            prop,
                            dbus_interface='org.freedesktop.DBus.Properties')
print("{} is: {}".format(prop, value))

看起来“Result”值并不是像其他许多输出那样的属性。

Answer 1

如果您查看https://www.freedesktop.org/wiki/Software/systemd/dbus/处的文档，它解释了Result是服务单元对象(org.freedesktop.systemd1.Service)的一部分。

所以，我将其添加到您的代码中:

if value == 'failed':
    result_prop = 'Result'
    result = myservice_proxy.Get('org.freedesktop.systemd1.Service',
                                 result_prop,
                                 dbus_interface='org.freedesktop.DBus.Properties')
    print(result)

现在它工作得很好!