repmgr: add -q/--quiet option

This suppresses log output below log level ERROR. This is useful mainly
when repmgr is being executed programmatically, e.g. in a cronjob,
where it's only useful to receive output if something goes wrong.

Note we advise against using this option when executing repmgr
commands which operate on PostgreSQL nodes (standby follow,
standby promote, standby switchover, node rejoin), particularly when
executed by repmgrd, as the log output will provide valuable
troubleshooting information.

Implements suggestion in GitHub #468.

HISTORY

@@ -8,6 +8,7 @@
         repmgr: "node check" and "node status" returns non-zero value if an issue
            encountered (Ian)
         repmgr: add CSV output mode to "cluster event"; GitHub #471 (Ian)
+        repmgr: add -q/--quiet option to suppress non-error output; GitHub #468 (Ian)
         repmgr: "node status" returns non-zero value if an issue encountered (Ian)
         repmgrd: create a PID file by default; GitHub #457 (Ian)
         repmgrd: daemonize process by default; GitHub #458 (Ian)

doc/appendix-release-notes.sgml

@@ -66,6 +66,13 @@
             </para>
           </listitem>
 
+          <listitem>
+            <para>
+              <application>repmgr</application>: add <option>-q/--quiet</option> option to suppress non-error
+              output. (GitHub #468).
+            </para>
+          </listitem>
+
           <listitem>
             <para>
               <command><link linkend="repmgr-cluster-show">repmgr cluster show</link></command>,

log.c

@@ -329,6 +329,13 @@ logger_set_terse(void)
 }
 
 
+void
+logger_set_level(int new_log_level)
+{
+	log_level = new_log_level;
+}
+
+
 void
 logger_set_min_level(int min_log_level)
 {
@@ -336,6 +343,7 @@ logger_set_min_level(int min_log_level)
 		log_level = min_log_level;
 }
 
+
 int
 detect_log_level(const char *level)
 {

log.h

@@ -129,6 +129,7 @@ bool		logger_shutdown(void);
 void		logger_set_verbose(void);
 void		logger_set_terse(void);
 void		logger_set_min_level(int min_log_level);
+void		logger_set_level(int new_log_level);
 
 void
 log_detail(const char *fmt,...)

repmgr-client-global.h

@@ -47,6 +47,7 @@ typedef struct
 	/* logging options */
 	char		log_level[MAXLEN];	/* overrides setting in repmgr.conf */
 	bool		log_to_file;
+	bool		quiet;
 	bool		terse;
 	bool		verbose;
 
@@ -138,7 +139,7 @@ typedef struct
 		/* general configuration options */	\
 		"", false, false, "", false, false,	\
 		/* logging options */ \
-		"", false, false, false, \
+		"", false, false, false, false,	\
 		/* output options */ \
 		false, false, false,  \
 		/* database connection options */ \

repmgr-client.c

@@ -182,7 +182,7 @@ main(int argc, char **argv)
 	/* Make getopt emitting errors */
 	opterr = 1;
 
-	while ((c = getopt_long(argc, argv, "?Vb:f:FwWd:h:p:U:R:S:D:ck:L:tvC:", long_options,
+	while ((c = getopt_long(argc, argv, "?Vb:f:FwWd:h:p:U:R:S:D:ck:L:qtvC:", long_options,
 							&optindex)) != -1)
 	{
 		/*
@@ -574,6 +574,12 @@ main(int argc, char **argv)
 				logger_output_mode = OM_DAEMON;
 				break;
 
+
+				/* --quiet */
+			case 'q':
+				runtime_options.quiet = true;
+				break;
+
 				/* --terse */
 			case 't':
 				runtime_options.terse = true;
@@ -1116,6 +1122,17 @@ main(int argc, char **argv)
 		logger_set_min_level(LOG_INFO);
 	}
 
+	/*
+	 * If -q/--quiet supplied, suppress any non-ERROR log output.
+	 * This overrides everything else; we'll leave it up to the user to deal with the
+	 * consequences of e.g. running --dry-run together with -q/--quiet.
+	 */
+	if (runtime_options.quiet == true)
+	{
+		logger_set_level(LOG_ERROR);
+	}
+
+
 
 	/*
 	 * Node configuration information is not needed for all actions, with
@@ -1934,6 +1951,7 @@ do_help(void)
 	printf(_("  --dry-run                           show what would happen for action, but don't execute it\n"));
 	printf(_("  -L, --log-level                     set log level (overrides configuration file; default: NOTICE)\n"));
 	printf(_("  --log-to-file                       log to file (or logging facility) defined in repmgr.conf\n"));
+	printf(_("  -q, --quiet                         suppress all log output apart from errors\n"));
 	printf(_("  -t, --terse                         don't display detail, hints and other non-critical output\n"));
 	printf(_("  -v, --verbose                       display additional log output (useful for debugging)\n"));
 

repmgr-client.h

@@ -126,6 +126,7 @@ static struct option long_options[] =
 /* logging options */
 	{"log-level", required_argument, NULL, 'L'},
 	{"log-to-file", no_argument, NULL, OPT_LOG_TO_FILE},
+	{"quiet",  no_argument, NULL, 'q'},
 	{"terse", no_argument, NULL, 't'},
 	{"verbose", no_argument, NULL, 'v'},