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Werk #19803: systemd_units: Fix false 'activating/reloading for X' alerts

Component Checks & agents
Title systemd_units: Fix false 'activating/reloading for X' alerts
Date May 4, 2026
Level Trivial Change
Class Bug Fix
Compatibility Compatible - no manual interaction needed
Checkmk versions & editions
3.0.0b1
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.5.0p3 Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.4.0p30 Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT

Previously, the Systemd Service Summary check on Linux hosts could emit a spurious WARN or CRIT of the form

Service 'X' activating for: Y minutes (warn/crit at A/B)

or

Service 'X' reloading for: Y minutes (warn/crit at A/B)

on services that had in fact finished within seconds. Affected services were typically timer-driven, e.g. mlocate.service, apt-daily.service, or phpsessionclean.service, or support reloading.

The Linux agent emits the systemd state via two independent systemctl invocations. If a timer fired between them, the parser merged the active state from the second snapshot with a duration from the first, producing the bogus alert.

The parser now sources the active state and the duration from the same snapshot, so the inconsistent merge — and the resulting false alerts for "activating" — no longer occur.

When a service is reloaded, the timestamp and the duration in the systemctl output continue to reflect the original activation, not the start of the reload. So, a service that has been running for two days and is currently reloading will still show

Active: reloading (reload) since … ; 2 days ago"

even if the reload itself only started seconds ago.

In future versions of Checkmk this can be addressed, but the required changes are too extensive for a released version. Hence, users observing false alerts for "reloading" have the option of a workaround: Unset the Tolerance period for 'reloading' state to prevent the service from going to WARN or CRIT.

Note: This will also silence any alert about services actually stuck in a reloading state.

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