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systemd: fix issue with dbus getting stuck at times by using private SessionBus #55

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karlicoss merged 1 commit into from
Dec 27, 2025
Merged

systemd: fix issue with dbus getting stuck at times by using private SessionBus #55

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18 changes: 10 additions & 8 deletions src/dron/systemd.py
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Original file line number Diff line number Diff line change
Expand Up @@ -243,7 +243,11 @@ def __init__(self) -> None:

self.Interface = Interface # meh

self.bus = SessionBus() # note: SystemBus is for system-wide services
# NOTE: private=True is important here! Otherwise SessionBus() returns a shared connection.
# If that connection gets into a broken state (e.g. timeouts), it will persist across BusManager instantiations,
# and result in DBusException: org.freedesktop.DBus.Error.NoReply
# Note that we instantiate BusManager every time we get systemd state, but seems like there is no need to cleanup/close bus, it doesn't seem to leak fds.
self.bus = SessionBus(private=True) # note: SystemBus is for system-wide services
systemd = self.bus.get_object(_sd(''), '/org/freedesktop/systemd1')
self.manager = Interface(systemd, dbus_interface=_sd('.Manager'))

Expand Down Expand Up @@ -377,8 +381,6 @@ def get_entries_for_monitor(managed: State, *, params: MonitorParams) -> list[Mo

UTCNOW = datetime.now(tz=UTC)

bus = BusManager()

entries: list[MonitorEntry] = []

# sort so that neigbouring unit.service/unit.timer go one after another for grouping
Expand Down Expand Up @@ -406,11 +408,11 @@ def get_entries_for_monitor(managed: State, *, params: MonitorParams) -> list[Mo
if timer is not None:
props = timer.dbus_properties
# FIXME this might be io bound? maybe make async or use thread pool?
cal = bus.prop(props, '.Timer', 'TimersCalendar')
next_ = bus.prop(props, '.Timer', 'NextElapseUSecRealtime')
cal = BusManager.prop(props, '.Timer', 'TimersCalendar')
next_ = BusManager.prop(props, '.Timer', 'NextElapseUSecRealtime')

# note: there is also bus.prop(props, '.Timer', 'LastTriggerUSec'), but makes more sense to use unit to account for manual runs
last = bus.prop(service_props, '.Unit', 'ActiveExitTimestamp')
last = BusManager.prop(service_props, '.Unit', 'ActiveExitTimestamp')

schedule = cal[0][1] # TODO is there a more reliable way to retrieve it??
# todo not sure if last is really that useful..
Expand Down Expand Up @@ -444,7 +446,7 @@ def get_entries_for_monitor(managed: State, *, params: MonitorParams) -> list[Mo
command = shlex.join(exec_start)
else:
command = None
_pid: int | None = int(bus.prop(service_props, '.Service', 'MainPID'))
_pid: int | None = int(BusManager.prop(service_props, '.Service', 'MainPID'))
pid = None if _pid == 0 else str(_pid)

if params.with_success_rate:
Expand All @@ -453,7 +455,7 @@ def get_entries_for_monitor(managed: State, *, params: MonitorParams) -> list[Mo
else:
rates = ''

service_result = bus.prop(service_props, '.Service', 'Result')
service_result = BusManager.prop(service_props, '.Service', 'Result')
status_ok = service_result == 'success'
status = f'{service_result:<9} {ago:<8}{rates}'

Expand Down