Merge pull request #1777 from jimklimov/issue-1590

Introduce optional `sd_notify()` support for READY, RELOADING and STOPPING states, and a WATCHDOG (if enabled)

NEWS

@@ -155,30 +155,30 @@ https://github.com/networkupstools/nut/milestone/8
    this variable unless troubleshooting, although other systems rely on it)
    [#805]
 
- - the nut-scanner program was updated to fall back to loading unresolved
+ - The nut-scanner program was updated to fall back to loading unresolved
    library filenames, hoping that `lt_dlopen()` implementation on the current
    platform would find library files better [#805]
 
- - detection of `libltdl` in `configure` script updated with fallback code to
+ - Detection of `libltdl` in `configure` script updated with fallback code to
    find it on systems that deliver the library to `/usr/local/lib` (e.g. on
    FreeBSD) [#1577]
 
- - an explicit `configure --with-nut-scanner` toggle was added, specifically
+ - An explicit `configure --with-nut-scanner` toggle was added, specifically
    so that build environments requesting `--with-all` but lack `libltdl` would
    abort and require either to install the dependency or explicitly forfeit
    the tool (some distro packages missed it quietly in the past) [#1560]
 
- - existing openssl-1.1.0 support added for NUT v2.8.0 release was tested to
+ - Existing openssl-1.1.0 support added for NUT v2.8.0 release was tested to
    be sufficient without deprecation warnings for builds against openssl-3.0.x
    (but no real-time testing was done yet) [#1547]
 
  - upslog: Added support for logging multiple devices with one call to the
    program [#1604]
 
- - some fixes applied to Solaris/illumos packaging and SMF service support
+ - Some fixes applied to Solaris/illumos packaging and SMF service support
    [#1554, #1564]
 
- - some fixes for builds on older OSes with less functional default system
+ - Some fixes for builds on older OSes with less functional default system
    shell interpreters - now `autogen.sh` supports a `CONFIG_SHELL` envvar
    to inject its value into generated `configure` script [#1736]
    * Note that you may have to install additional tools (possibly from
@@ -222,6 +222,13 @@ https://github.com/networkupstools/nut/milestone/8
    encouraged to pick optimal location for their distributions (which
    remains mounted at least read-only late in shutdown) [#529]
 
+ - Extended Linux systemd support with optional notifications about daemon
+   state (READY, RELOADING, STOPPING) and watchdog keep-alive messages [#1590]
+
+ - Extended Linux systemd units with aliases named after the daemons:
+   `nut-server.service` as `upsd.service`, and `nut-monitor.service` as
+   `upsmon.service` (so simple `systemctl reload upsd` can work) [#1777]
+
  - Further revision of public headers delivered by NUT was done, particularly
    to address lack of common data types (`size_t`, `ssize_t`, `uint16_t`,
    `time_t` etc.) in third-party client code that earlier sufficed to only

UPGRADING

@@ -47,7 +47,7 @@ Changes from 2.8.0 to 2.8.1
   serial drivers in respective Makefile and configure script options - this
   may impact packaging decisions on some distributions going forward [#1446]
 
-- an explicit `configure --with-nut-scanner` toggle was added, specifically
+- An explicit `configure --with-nut-scanner` toggle was added, specifically
   so that build environments requesting `--with-all` but lacking `libltdl`
   would abort and require the packager either to install the dependency
   or explicitly forfeit building the tool (some distro packages missed it
@@ -66,6 +66,13 @@ Changes from 2.8.0 to 2.8.1
   * Several other issues have been fixed related to this file and its content,
     including #1030, #1037, #1117 and #1712
 
+- Extended Linux systemd support with optional notifications about daemon
+  state (READY, RELOADING, STOPPING) and watchdog keep-alive messages.
+  Note that `WatchdogSec=` values are currently NOT pre-set into systemd
+  unit file templates provided by NUT, this is an exercise for end-users
+  based on sizing of their deployments and performance of monitoring station
+  [#1590, #1777]
+
 - snmp-ups: some subdrivers (addressed using the driver parameter `mibs`)
   were renamed: `pw` is now `eaton_pw_nm2`, and `pxgx_ups` is `eaton_pxg_ups`
   [#1715]

clients/upslog.c

@@ -618,7 +618,11 @@ int main(int argc, char **argv)
 
 	compile_format();
 
+	upsnotify(NOTIFY_STATE_READY_WITH_PID, NULL);
+
 	while (exit_flag == 0) {
+		upsnotify(NOTIFY_STATE_WATCHDOG, NULL);
+
 		time(&now);
 
 		if (nextpoll > now) {
@@ -631,10 +635,12 @@ int main(int argc, char **argv)
 		}
 
 		if (reopen_flag) {
+			upsnotify(NOTIFY_STATE_RELOADING, NULL);
 			upslogx(LOG_INFO, "Signal %d: reopening log file",
 				reopen_flag);
 			reopen_log();
 			reopen_flag = 0;
+			upsnotify(NOTIFY_STATE_READY, NULL);
 		}
 
 		for (monhost_ups_current = monhost_ups_anchor;
@@ -657,6 +663,8 @@ int main(int argc, char **argv)
 	}
 
 	upslogx(LOG_INFO, "Signal %d: exiting", exit_flag);
+	upsnotify(NOTIFY_STATE_STOPPING, "Signal %d: exiting", exit_flag);
+
 	for (monhost_ups_current = monhost_ups_anchor;
 	     monhost_ups_current != NULL;
 	     monhost_ups_current = monhost_ups_current->next) {

clients/upsmon.c

@@ -621,6 +621,8 @@ static void doshutdown(void)
 
 static void doshutdown(void)
 {
+	upsnotify(NOTIFY_STATE_STOPPING, "Executing automatic power-fail shutdown");
+
 	/* this should probably go away at some point */
 	upslogx(LOG_CRIT, "Executing automatic power-fail shutdown");
 	wall("Executing automatic power-fail shutdown\n");
@@ -2580,6 +2582,7 @@ int main(int argc, char *argv[])
 	}
 
 	if (upscli_init(certverify, certpath, certname, certpasswd) < 0) {
+		upsnotify(NOTIFY_STATE_STOPPING, "Failed upscli_init()");
 		exit(EXIT_FAILURE);
 	}
 
@@ -2590,15 +2593,22 @@ int main(int argc, char *argv[])
 	closelog();
 	open_syslog(prog);
 
+	upsnotify(NOTIFY_STATE_READY_WITH_PID, NULL);
+
 	while (exit_flag == 0) {
 		utype_t	*ups;
 
+		upsnotify(NOTIFY_STATE_WATCHDOG, NULL);
+
 		/* check flags from signal handlers */
 		if (userfsd)
 			forceshutdown();
 
-		if (reload_flag)
+		if (reload_flag) {
+			upsnotify(NOTIFY_STATE_RELOADING, NULL);
 			reload_conf();
+			upsnotify(NOTIFY_STATE_READY, NULL);
+		}
 
 		for (ups = firstups; ups != NULL; ups = ups->next)
 			pollups(ups);
@@ -2676,6 +2686,7 @@ int main(int argc, char *argv[])
 	}
 
 	upslogx(LOG_INFO, "Signal %d: exiting", exit_flag);
+	upsnotify(NOTIFY_STATE_STOPPING, "Signal %d: exiting", exit_flag);
 	upsmon_cleanup();
 
 	exit(EXIT_SUCCESS);

common/Makefile.am

@@ -73,6 +73,22 @@ endif
 libcommon_la_LIBADD = libparseconf.la @LTLIBOBJS@ @NETLIBS@
 libcommonclient_la_LIBADD = libparseconf.la @LTLIBOBJS@ @NETLIBS@
 
+libcommon_la_CFLAGS = $(AM_CFLAGS)
+libcommonclient_la_CFLAGS = $(AM_CFLAGS)
+
+# Did the user request, and build env support, tighter integration with
+# libsystemd methods such as sd_notify()?
+if WITH_LIBSYSTEMD
+  libcommon_la_CFLAGS += $(LIBSYSTEMD_CFLAGS)
+  libcommon_la_LIBADD += $(LIBSYSTEMD_LIBS)
+
+# A typical client should not need this,
+# but just in case (and to simplify linking)...
+#  libcommonclient_la_CFLAGS += $(LIBSYSTEMD_CFLAGS)
+#  libcommonclient_la_LIBADD += $(LIBSYSTEMD_LIBS)
+  libcommonclient_la_CFLAGS += -DWITHOUT_LIBSYSTEMD=1
+endif
+
 MAINTAINERCLEANFILES = Makefile.in .dirstamp
 
 # NOTE: Do not clean ".deps" in SUBDIRS of the main project,