Teach upsdrvctl to list device config names and show run-time status, and to optionally hide the start-up banner

NEWS.adoc

@@ -91,6 +91,15 @@ https://github.com/networkupstools/nut/milestone/11
    command for a protocol equivalent of sending a `SIGTERM`, e.g. when
    a newer instance of the driver program tries to start. [#1903, #2392]
 
+ - A new `NUT_QUIET_INIT_BANNER` envvar (presence or "true" value) can now
+   prevent the tool name and NUT version banner from being unilaterally
+   printed out when NUT programs start. [issues #1789 vs. #316]
+
+ - Extended `upsdrvctl` with a `list` operation (or `-l` option) to report
+   manageable device configuration names (possible `<ups>` arguments to
+   `start`, `stop` etc. operations), or to confirm a single name that it
+   is known, and a `status` operation for more information. [#2567]
+
  - riello_ser updates:
    * added `localcalculation` option to compute `battery.runtime` and
      `battery.charge` if the device provides bogus values [issue #2390,

UPGRADING.adoc

@@ -100,6 +100,16 @@ Changes from 2.8.2 to 2.8.3
   Also the NUT daemons should request to double-check against their
   run-time process name (if it can be detected). [issue #2463]
 
+- More environment variable support was added to NUT programs, primarily
+  aimed at wrappers such as init scripts and service unit definitions,
+  allowing to tweak what (and whether) they write into debug traces, and
+  so "make noise" or "bring invaluable insights" to logs or terminal;
+  they can generally be used for services and init scripts via `nut.conf`:
+  * See `NUT_IGNORE_CHECKPROCNAME` and `NUT_DEBUG_SYSLOG` above. [#1915]
+  * A `NUT_QUIET_INIT_BANNER` envvar (presence or "true" value) prevents
+    tool name and NUT version banner from being printed out when programs
+    start. [issues #1789 vs. #316]
+
 
 Changes from 2.8.1 to 2.8.2
 ---------------------------

clients/upslog.c

@@ -439,7 +439,10 @@ int main(int argc, char **argv)
 	logformat = DEFAULT_LOGFORMAT;
 	user = RUN_AS_USER;
 
-	printf("Network UPS Tools %s %s\n", prog, UPS_VERSION);
+	if (!banner_is_disabled()) {
+		printf("Network UPS Tools %s %s\n", prog, UPS_VERSION);
+		fflush(stdout);
+	}
 
 	while ((i = getopt(argc, argv, "+hs:l:i:f:u:Vp:FBm:")) != -1) {
 		switch(i) {

clients/upsmon.c

@@ -2908,8 +2908,10 @@ int main(int argc, char *argv[])
 	}
 #endif
 
-	printf("Network UPS Tools %s %s\n", prog, UPS_VERSION);
-	fflush(stdout);
+	if (!banner_is_disabled()) {
+		printf("Network UPS Tools %s %s\n", prog, UPS_VERSION);
+		fflush(stdout);
+	}
 
 	/* if no configuration file is specified on the command line, use default */
 	configfile = xmalloc(SMALLBUF);

common/common.c

@@ -189,6 +189,26 @@ int syslog_is_disabled(void)
 	return value;
 }
 
+int banner_is_disabled(void)
+{
+	static int value = -1;
+
+	if (value < 0) {
+		char *s = getenv("NUT_QUIET_INIT_BANNER");
+		/* Envvar present and empty or true-ish means NUT tool name+version
+		 * banners disabled by the setting: default is enabled (inversed per
+		 * method name) */
+		value = 0;
+		if (s) {
+			if (*s == '\0' || !strcasecmp(s, "true") || strcmp(s, "1")) {
+				value = 1;
+			}
+		}
+	}
+
+	return value;
+}
+
 /* enable writing upslog_with_errno() and upslogx() type messages to
    the syslog */
 void syslogbit_set(void)
@@ -1411,17 +1431,15 @@ pid_t parsepid(const char *buf)
 	return pid;
 }
 
-/* open pidfn, get the pid, then send it sig
+/* open pidfn, get the pid;
  * returns negative codes for errors, or
- * zero for a successfully sent signal
+ * zero for a successfully discovered value
  */
-#ifndef WIN32
-int sendsignalfn(const char *pidfn, int sig, const char *progname, int check_current_progname)
+pid_t parsepidfile(const char *pidfn)
 {
 	char	buf[SMALLBUF];
 	FILE	*pidf;
 	pid_t	pid = -1;
-	int	ret = -1;
 
 	pidf = fopen(pidfn, "r");
 	if (!pidf) {
@@ -1441,7 +1459,9 @@ int sendsignalfn(const char *pidfn, int sig, const char *progname, int check_cur
 		fclose(pidf);
 		return -2;
 	}
-	/* TOTHINK: Original code only closed pidf before
+
+	/* TOTHINK: Original sendsignalfn code (which this
+	 * was extracted from) only closed pidf before
 	 * exiting the method, on error or "normally".
 	 * Why not here? Do we want an (exclusive?) hold
 	 * on it while being active in the method?
@@ -1450,12 +1470,26 @@ int sendsignalfn(const char *pidfn, int sig, const char *progname, int check_cur
 	/* this method actively reports errors, if any */
 	pid = parsepid(buf);
 
+	fclose(pidf);
+
+	return pid;
+}
+
+/* open pidfn, get the pid, then send it sig
+ * returns negative codes for errors, or
+ * zero for a successfully sent signal
+ */
+#ifndef WIN32
+int sendsignalfn(const char *pidfn, int sig, const char *progname, int check_current_progname)
+{
+	int	ret = -1;
+	pid_t	pid = parsepidfile(pidfn);
+
 	if (pid >= 0) {
 		/* this method actively reports errors, if any */
 		ret = sendsignalpid(pid, sig, progname, check_current_progname);
 	}
 
-	fclose(pidf);
 	return ret;
 }
 

conf/nut.conf.sample

@@ -9,11 +9,16 @@
 #
 # IMPORTANT NOTES:
 #  This file is intended to be sourced by standard POSIX shell scripts
-#  (so there is no guaranteed `export VAR=VAL` syntax) and additionally
-#  by systemd on Linux (no guaranteed expansion of variables).
+#  (so there is no guaranteed `export VAR=VAL` syntax, while you may need
+#  to `export VAR` when sourcing it into init-scripts, for propagation to
+#  NUT programs eventually), and additionally by systemd on Linux (with no
+#  guaranteed expansion of variables -- only verbatim assignments).
+#
 #  You MUST NOT use spaces around the equal sign!
+#
 #  Practical support for this file and its settings currently varies between
 #  various OS packages and NUT sample scripts, but should converge over time.
+#
 #  Contents of this file should be pure ASCII (character codes not in range
 #  would be ignored with a warning message).
 #
@@ -93,6 +98,13 @@ MODE=none
 # verbosity passed to NUT daemons. As an environment variable, its priority sits
 # between that of 'DEBUG_MIN' setting of a driver and the command-line options.
 #NUT_DEBUG_LEVEL=0
+#export NUT_DEBUG_LEVEL
+
+# Optionally add current process ID to tags with debug-level identifiers.
+# This may be useful when many NUT daemons write to the same console or log
+# file, such as in containers/plugins for Home Assistant, storage appliances...
+#NUT_DEBUG_PID=true
+#export NUT_DEBUG_PID
 
 # Normally NUT can (attempt to) use the syslog or Event Log (WIN32), but the
 # environment variable 'NUT_DEBUG_SYSLOG' allows to bypass it, and perhaps keep
@@ -103,6 +115,7 @@ MODE=none
 #  `none`    Disabled and background() detaches stderr as usual
 #  `default`/unset/other   Not disabled
 #NUT_DEBUG_SYSLOG=stderr
+#export NUT_DEBUG_SYSLOG
 
 # Normally NUT can (attempt to) verify that the program file name matches the
 # name associated with a running process, when using PID files to send signals.
@@ -112,3 +125,37 @@ MODE=none
 # optionally set in init-scripts or service methods for `upsd`, `upsmon` and
 # NUT drivers/`upsdrvctl`.
 #NUT_IGNORE_CHECKPROCNAME=true
+#export NUT_IGNORE_CHECKPROCNAME
+
+# Optional flag to prevent daemons which can notify service management frameworks
+# (such as systemd) about passing their lifecycle milestones, to not report
+# loudly if they could NOT do so (e.g. running on a system without a framework,
+# or misconfigured so they could not report and the OS could eventually restart
+# the false-positively identified "unresponsive" service.
+# Currently such reports, done by default, help troubleshoot service start-up
+# and highlight that NUT sources (or package build) did not take advantage of
+# tighter OS service management framework integration (if one exists, so that
+# developers could focus on adding that). Reasons to set this flag could include
+# platforms without such a framework and not expecting one, although nagging
+# your favourite OS or contributing development to make it better is also a way.
+#NUT_QUIET_INIT_UPSNOTIFY=true
+#export NUT_QUIET_INIT_UPSNOTIFY
+
+##############################################################################
+# Variables that can be helpful more for tool scripting than service daemons
+##############################################################################
+
+# Optionally prevent `libupsclient` consumers (notoriously `upsc`, maybe
+# also `dummy-ups` driver or `nut-scanner` tool) from reporting whether
+# they have initialized SSL support -- or, loudly, failed to initialize
+# as it was not configured on this system.
+#NUT_QUIET_INIT_SSL=true
+#export NUT_QUIET_INIT_SSL
+
+# Optionally suppress NUT tool name and version banner (normally shown in most
+# NUT programs unilaterally, before processing any CLI options and possibly
+# failing due to that).
+# NOT recommended for services due to adverse troubleshooting impact, but may
+# be helpful in shell profiles or scripts which process NUT tool outputs.
+#NUT_QUIET_INIT_BANNER=true
+#export NUT_QUIET_INIT_BANNER

docs/maintainer-guide.txt

@@ -228,6 +228,8 @@ MAINTAINER SANDBOX (to be completed and pushed)
 
 * announce on mailing list, IRC, etc.
 
+* update https://en.wikipedia.org/wiki/Network_UPS_Tools
+
 * create a GitHub issue label for the new release, e.g. at
   https://github.com/networkupstools/nut/labels?q=impact :
 ----

docs/man/nut.conf.txt

@@ -23,10 +23,23 @@ comments.
 IMPORTANT NOTES
 ---------------
 
-* This file is intended to be sourced by shell scripts.
+* This file is intended to be sourced by shell scripts as well as by
+  service management frameworks like systemd on Linux:
+  - There is no guaranteed `export VAR=VAL` syntax
+  - No guaranteed expansion of variables like `VAR1="$VAR2-something"` --
+    only verbatim assignments
+  - You may need to `export VAR` when sourcing it into init-scripts
+    or other scripts, for eventual propagation of certain settings
+    to NUT programs. Not-exported variables can only be consumed by
+    the script which "sourced" the file (and may choose to `export`
+    them independently).
 
 * You MUST NOT use spaces around the equal sign!
 
+* Practical support for this file and its settings currently varies
+  between different OS packages and NUT sample scripts, but should
+  converge over time.
+
 * Contents of this file should be pure ASCII (character codes
   not in range would be ignored with a warning message).
 
@@ -122,6 +135,11 @@ Optional, defaults to `0`. This setting controls the default debugging message
 verbosity passed to NUT daemons. As an environment variable, its priority sits
 between that of 'DEBUG_MIN' setting of a driver and the command-line options.
 
+*NUT_DEBUG_PID*::
+Optionally add current process ID to tags with debug-level identifiers.
+This may be useful when many NUT daemons write to the same console or log
+file, such as in containers/plugins for Home Assistant, storage appliances...
+
 *NUT_DEBUG_SYSLOG*::
 Optional, unset by default.
 Normally NUT can (attempt to) use the syslog or Event Log (WIN32), but the
@@ -151,6 +169,20 @@ and do not match built-in expectations).
 This environment variable can also be optionally set in init-scripts or
 service methods for `upsd`, `upsmon` and NUT drivers/`upsdrvctl`.
 
+*NUT_QUIET_INIT_UPSNOTIFY*::
+Optional flag to prevent daemons which can notify service management frameworks
+(such as systemd) about passing their lifecycle milestones, to not report
+loudly if they could NOT do so (e.g. running on a system without a framework,
+or misconfigured so they could not report and the OS could eventually restart
+the false-positively identified "unresponsive" service.
++
+Currently such reports, done by default, help troubleshoot service start-up
+and highlight that NUT sources (or package build) did not take advantage of
+tighter OS service management framework integration (if one exists, so that
+developers could focus on adding that). Reasons to set this flag could include
+platforms without such a framework and not expecting one, although nagging
+your favourite OS or contributing development to make it better is also a way.
+
 EXAMPLE
 -------
 

docs/man/upsdrvctl.txt

@@ -11,7 +11,9 @@ SYNOPSIS
 
 *upsdrvctl* -h
 
-*upsdrvctl* ['OPTIONS'] {start | stop | shutdown} ['ups']
+*upsdrvctl* ['OPTIONS'] {start | stop | shutdown | status} ['ups']
+
+*upsdrvctl* ['OPTIONS'] {list | -l} ['ups']
 
 *upsdrvctl* ['OPTIONS'] -c COMMAND ['ups']
 
@@ -81,6 +83,9 @@ this mode (not saved by default when staying in foreground).
 Drivers will run in the background, regardless of debugging settings,
 as set by *-D* and passed-through by *-d* options.
 
+*-l*::
+Alias for `list` command.
+
 COMMANDS
 --------
 
@@ -118,6 +123,55 @@ NOTE: refer to linkman:ups.conf[5] for using the *nowait* parameter.
 It can be overridden by `NUT_IGNORE_NOWAIT` environment variable
 (e.g. used to work around certain issues with systemd otherwise).
 
+*list*::
+Without a further argument, report all currently known device configuration
+names to `stdout`, one per line. With an argument, also try to report that
+name, but exit with an error code if that name is not known.
+
+NOTE: The tool would exit with an error if `ups.conf` file is not found,
+readable, or does not define any device sections (whose names are reported
+here and managed in other commands).
+
+NOTE: The tool name and NUT version banner line is also printed to `stdout`
+before any other processing. This can be suppressed by `NUT_QUIET_INIT_BANNER`
+environment variable (exported by caller and empty or "true").
+
+*status*::
+Similar to `list`, but reports more information -- also the driver name, the
+PID if it is running, and result of a signal probe to check it is responding.
+The `NUT_QUIET_INIT_BANNER` suppression can be helpful for scripted parsing.
+If there is anything to print (at least one device is known), the first line
+of status report would be the heading with column names:
+
+	:; NUT_QUIET_INIT_BANNER=true upsdrvctl status
+	UPSNAME UPSDRV  PF_RUNNING      PF_PID  S_RESPONSIVE    S_PID   S_STATUS
+	dummy   dummy-ups       N/A     -3      NOT_RESPONSIVE  N/A
+	eco650  usbhid-ups      RUNNING 3559207 RESPONSIVE      3559207 "OL"
+	UPS2    dummy-ups       RUNNING 31455   RESPONSIVE      31455   "OL BOOST"
+
+Values are TAB-separated. Any complex string values would be encased in
+double-quotes.
+
+Fields reported (`PF_*` = according to PID file, if any; `S_*` = via socket
+protocol):
+
+        *UPSNAME*;;      driver section configuration name
+        *UPSDRV*;;       driver program name per `ups.conf`
+        *PF_RUNNING*;;   `RUNNING` if `PF_PID` is valid (PID file existed,
+                         PID was parsed out of it and found running, program
+                         name corresponds to driver, etc.); `STOPPED` if PID
+                         was parsed but not running or has a wrong program
+                         name; "N/A" if failed to parse it or no PID file
+        *PF_PID*;;       PID of driver according to PID file (if any), or some
+                         negative values upon errors (as defined in `common.c`)
+        *S_RESPONSIVE*;; `RESPONSIVE` if `PING`/`PONG` during socket protocol
+                         session setup succeeded; `NOT_RESPONSIVE` otherwise
+        *S_PID*;;        PID of driver according to `GETPID` active query
+        *S_STATUS*;;     Value of `ups.status` variable
+
+This mode does not discover drivers that are not in `ups.conf` (e.g. started
+manually for experiments with many `-x` CLI options).
+
 *-c* 'command'::
 Send 'command' to the background process as a signal.  Valid commands
 are:

docs/man/upsdrvsvcctl.txt

@@ -127,6 +127,11 @@ by using the 'maxretry' and 'retrydelay' options - see linkman:ups.conf[5].
 *stop*::
 Stop the UPS driver(s).
 
+*status*::
+Query run-time status of all configured devices (or one specified device).
+Currently defers work to linkman:upsdrvctl[8], and does not report service
+unit information.
+
 *upsdrvsvcctl* also supports further operations for troubleshooting the
 mapping of NUT driver section names to the service instance names (which
 may differ due to limitations of various systems).