Merge pull request networkupstools#2891 from jimklimov/issue-2638

Introduce `nut-udev-settle.service` for systemd integration

Author: jimklimov

Makefile.am

@@ -1111,6 +1111,7 @@ install-as-root:
 			@SYSTEMD_SYSTEMCTL_PROGRAM@ stop nut-monitor.service nut-server.service || true ; \
 			@SYSTEMD_SYSTEMCTL_PROGRAM@ stop nut-driver.service || true ; \
 			@SYSTEMD_SYSTEMCTL_PROGRAM@ stop nut-driver.target || true ; \
+			@SYSTEMD_SYSTEMCTL_PROGRAM@ stop nut-udev-settle.service || true ; \
 			@SYSTEMD_SYSTEMCTL_PROGRAM@ stop nut.target || true ; \
 		fi ; \
 		if $(WITH_SOLARIS_SMF) || $(WITH_SOLARIS_INIT) ; then \
@@ -1222,8 +1223,8 @@ install-as-root:
 				@SYSTEMD_SYSTEMCTL_PROGRAM@ preset-all || exit ; \
 			else \
 				echo "$@: Apply systemd enabled/disabled service defaults" >&2 ; \
-				@SYSTEMD_SYSTEMCTL_PROGRAM@ disable nut.target nut-driver.target nut-monitor nut-server nut-driver-enumerator.path nut-driver-enumerator.service || exit ; \
-				@SYSTEMD_SYSTEMCTL_PROGRAM@ enable  nut.target nut-driver.target nut-monitor nut-server nut-driver-enumerator.path nut-driver-enumerator.service || exit ; \
+				@SYSTEMD_SYSTEMCTL_PROGRAM@ disable nut.target nut-driver.target nut-udev-settle.service nut-monitor nut-server nut-driver-enumerator.path nut-driver-enumerator.service || exit ; \
+				@SYSTEMD_SYSTEMCTL_PROGRAM@ enable  nut.target nut-driver.target nut-udev-settle.service nut-monitor nut-server nut-driver-enumerator.path nut-driver-enumerator.service || exit ; \
 			fi ; \
 			echo "$@: Reconfigure nut-driver-enumerator (service instance wrapping)" >&2 ; \
 			@SYSTEMD_SYSTEMCTL_PROGRAM@ restart udev && applied_udev=true || true ; \

NEWS.adoc

@@ -476,6 +476,9 @@ This requirement compromises usability of `make distcheck` on platforms without
      suspending the `upsmon` process, etc. [#2597]
    * Introduced delivery of default systemd presets (lists of enabled/disabled
      units). [#2721]
+   * A `nut-udev-settle.service` was introduced to replace dependency on the
+     `systemd-udev-settle.service` which is deprecated and causes warnings on
+     some systems. It was shown to benefit NUT use-cases however. [#2638]
 
  - gamatronic driver revised for safer memory operations; this was reported
    to have fixed a Segmentation Fault seen in earlier NUT releases with

UPGRADING.adoc

@@ -48,6 +48,10 @@ Changes from 2.8.2 to 2.8.3
   disable certain NUT units by default; its comments document each choice.
   [issue #2721]
 
+- A `nut-udev-settle.service` was introduced to replace dependency on the
+  `systemd-udev-settle.service` which is deprecated and causes warnings on
+  some systems. It was shown to benefit NUT use-cases however. [#2638]
+
 - Reference packages prepared by `make package` should now separate the
   `PACKAGE_VERSION` from the platform-dependent prefix by a dash character
   in the ultimate package file name. Previously they were glued together

scripts/python/Makefile.am

@@ -92,16 +92,23 @@ NUT_MONITOR_COMMON_TEMPLATE = \
 install-data-hook-app-locale-symlinks:
 	@cd "$(DESTDIR)$(nutmonitordir)/app/locale" && \
 	 for L in fr it ru ; do \
-	    $(LN_S) "$$L".po "$$L"/"$$L"_"`echo "$$L" | tr '[a-z]' '[A-Z]'`".UTF-8.po || exit ; \
-	    $(LN_S) "$$L" "$$L"_"`echo "$$L" | tr '[a-z]' '[A-Z]'`".UTF-8 || exit ; \
+	    UTF8_NAME="$$L"_"`echo "$$L" | tr '[a-z]' '[A-Z]'`".UTF-8 || exit ; \
+	    UTF8_POFILE="$${L}/$${UTF8_NAME}.po" || exit ; \
+	    UTF8_SUBDIR="$${UTF8_NAME}" || exit ; \
+	    rm -f "$${UTF8_POFILE}" || true ; rm -f "$${UTF8_SUBDIR}" || true ; \
+	    $(LN_S) "$$L".po "$${UTF8_POFILE}" || exit ; \
+	    $(LN_S) "$$L" "$${UTF8_SUBDIR}" || exit ; \
 	 done
 
 uninstall-hook-app-locale-symlinks:
 	@RES=0 ; \
 	 cd "$(DESTDIR)$(nutmonitordir)/app/locale" && \
 	 for L in fr it ru ; do \
-	    rm -f "$$L"/"$$L"_"`echo "$$L" | tr '[a-z]' '[A-Z]'`".UTF-8.po || RES=$$? ; \
-	    rm -f "$$L"_"`echo "$$L" | tr '[a-z]' '[A-Z]'`".UTF-8 || RES=$$? ; \
+	    UTF8_NAME="$$L"_"`echo "$$L" | tr '[a-z]' '[A-Z]'`".UTF-8 || exit ; \
+	    UTF8_POFILE="$${L}/$${UTF8_NAME}.po" || exit ; \
+	    UTF8_SUBDIR="$${UTF8_NAME}" || exit ; \
+	    rm -f "$${UTF8_POFILE}" || RES=$$? ; \
+	    rm -f "$${UTF8_SUBDIR}" || RES=$$? ; \
 	 done ; \
 	 exit $$RES
 

scripts/systemd/Makefile.am

@@ -15,6 +15,7 @@ systemdsystemunit_DATA = \
         nut-monitor.service \
         nut-server.service  \
         nut-driver.target   \
+        nut-udev-settle.service \
         nut.target
 
 if !WITH_LIBSYSTEMD_INHIBITOR
@@ -29,7 +30,7 @@ systemdsystempreset_DATA = \
         nut-systemd.preset
 
 # Add files not generated from .in templates
-EXTRA_DIST += nut-sleep.service nut-systemd.preset
+EXTRA_DIST += nut-sleep.service nut-systemd.preset nut-udev-settle.service
 
 systemdshutdown_SCRIPTS = nutshutdown
 
@@ -41,7 +42,7 @@ else !HAVE_SYSTEMD
 EXTRA_DIST += \
 	nut.target.in nut-systemd.preset \
 	nut-driver@.service.in nut-driver.target.in \
-	nut-server.service.in \
+	nut-server.service.in nut-udev-settle.service \
 	nut-logger.service.in nut-monitor.service.in \
 	nut-sleep.service nutshutdown.in \
 	nut-driver-enumerator.path.in nut-driver-enumerator.service.in \

scripts/systemd/nut-server.service.in

@@ -39,9 +39,9 @@ Documentation=@NUT_WEBSITE_BASE@/docs/man/nut.conf.html
 [Service]
 # A busy server can be monitoring a lot of devices as well as replying
 # to many clients. The "infinity" definition is actually capped by OS
-# settings and hardcoded defaults; typically can be 65535+ nowadays.
+# settings and hard-coded defaults; typically can be 65535+ nowadays.
 # On 64-bit distros this can well be set into hundreds of thousands
-# as well (though note each connnection has a CPU and RAM overhead
+# as well (though note each connection has a CPU and RAM overhead
 # so one can strike physical limits upon deployment and/or bring the
 # poorly sized system to a crawl, or worse). On a running system you
 # can check /proc/$MAINPID/limits for active ulimits of the process.

scripts/systemd/nut-systemd.preset

@@ -39,6 +39,10 @@ enable nut-driver.target
 # I don't think a template can be activated/deactivated; anyhow
 # this is NDE's bread and butter at run-time:
 #enable nut-driver@.service
+# The nut-udev-settle.service would be used by USB/Serial/... drivers
+# wrapped by NDE, and so referenced there if needed. It should not
+# auto-start if not used by any driver:
+enable nut-udev-settle.service
 
 # Activate the "upsd" data server, to represent drivers on the network.
 # Requires "ups.conf", "upsd.conf", "upsd.users":

scripts/systemd/nut-udev-settle.service

@@ -0,0 +1,47 @@
+# Network UPS Tools (NUT) systemd integration
+# Copyright (C) 2025- by NUT contributors
+# Distributed under the terms of GPLv2+
+# See https://networkupstools.org/
+# and https://github.com/networkupstools/nut/
+#
+# This file was adapted from systemd-udev-settle.service provided as part of
+# systemd. The original service is no longer recommended for general use in
+# recent distributions (does not guarantee reliable detection, and delays
+# system readiness for log-in), but waiting for udev to settle its currently
+# running operations has proven useful in some cases for NUT practice.
+#
+# Original file's terms:
+#
+#  SPDX-License-Identifier: LGPL-2.1-or-later
+#
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+# This service can dynamically be pulled-in by legacy services which
+# cannot reliably cope with dynamic device configurations, and wrongfully
+# expect a populated /dev during bootup.
+
+[Unit]
+Description=Wait for udev To Complete Device Initialization before USB-capable NUT drivers start
+Documentation=man:systemd-udev-settle.service(8)
+DefaultDependencies=no
+Wants=systemd-udevd.service
+After=systemd-udev-trigger.service
+ConditionPathIsReadWrite=/sys
+
+# Used when/if requested by specific nut-driver@.service instances.
+# No auto-start or dependency otherwise.
+
+[Service]
+Type=oneshot
+TimeoutSec=180
+# We want to re-trigger this service during NUT driver restarts
+# (maybe several at once) as we reconnect after e.g. USB bus reset,
+# for changes in USB/Serial/... devices that may need permissions
+# for NUT to be applied. So we do not want it to remain "active".
+#RemainAfterExit=yes
+ExecStart=udevadm settle

scripts/upsdrvsvcctl/nut-driver-enumerator.sh.in

@@ -109,8 +109,11 @@ fi
 ### Also can tune whether a driver "Wants" another service (would consider
 ### ordering if that one is enabled, but live if it is disabled), or if it
 ### "Requires" that (would cause that to start).
-DEPSVC_USB_SYSTEMD="systemd-udev.service systemd-udev-settle.service"
+DEPSVC_USB_SYSTEMD="systemd-udevd.service nut-udev-settle.service"
 DEPREQ_USB_SYSTEMD="Wants"
+# Serial drivers may rely on USB dongles or even custom-owned real ports:
+DEPSVC_SERIAL_SYSTEMD="systemd-udevd.service nut-udev-settle.service"
+DEPREQ_SERIAL_SYSTEMD="Wants"
 DEPSVC_NET_FULL_SYSTEMD="network-online.target systemd-resolved.service ifplugd.service"
 DEPREQ_NET_FULL_SYSTEMD="Wants"
 DEPSVC_NET_LOCAL_SYSTEMD="network.target"
@@ -644,6 +647,7 @@ upsconf_getDriverMedia() {
                     printf '%s\n%s\n' "$CURR_DRV" "" ; return ;;
             esac
             ;;
+        # FIXME: other modbus? sysfs like INA219? GPIO? Other local devices?
         *)  printf '%s\n%s\n' "$CURR_DRV" "" ; return ;;
     esac
 }
@@ -949,8 +953,11 @@ systemd_registerInstance() {
         network)
             DEPSVC="$DEPSVC_NET_FULL_SYSTEMD"
             DEPREQ="$DEPREQ_NET_FULL_SYSTEMD" ;;
-        serial) ;;
+        serial)
+            DEPSVC="$DEPSVC_SERIAL_SYSTEMD"
+            DEPREQ="$DEPREQ_SERIAL_SYSTEMD" ;;
         '') ;;
+        # FIXME: modbus? sysfs like INA219? GPIO? Other local devices?
         *)  echo "WARNING: Unexpected NUT media type ignored: '${_MED}'" >&2 ;;
     esac
     if [ -n "$DEPSVC" ]; then