repmgr standby switchover: add "%p" event notification parameter

This will contain the node ID of the former primary.

HISTORY

@@ -2,7 +2,10 @@
         repmgr: enable documentation to be build as single HTML file; GitHub #353 (fanf2)
         repmgr: add missing -W option to getopt_long() invocation; GitHub #350 (Ian)
         repmgr: recognize "--terse" option for "repmgr cluster event"; GitHub #360 (Ian)
-        docs: various fixes (Ian, Daymel, Martín, ams)
+        repmgr: add "--wait-start" option for "repmgr standby register"; GitHub #356 (Ian)
+        repmgr: add "%p" event notification parameter for "repmgr standby switchover"
+          containing the node ID of the demoted primary (Ian)
+        docs: various fixes and updates (Ian, Daymel, Martín, ams)
 
 4.0.1   2017-12-13
         repmgr: ensure "repmgr node check --action=" returns appropriate return

dbutils.c

@@ -2962,7 +2962,6 @@ create_event_record(PGconn *conn, t_configuration_options *options, int node_id,
 }
 
 
-
 /*
  * create_event_notification()
  *
@@ -3063,7 +3062,7 @@ _create_event(PGconn *conn, t_configuration_options *options, int node_id, char
 
 		if (PQresultStatus(res) != PGRES_TUPLES_OK)
 		{
-			/* we don't treat this as an error */
+			/* we don't treat this as a fatal error */
 			log_warning(_("unable to create event record:\n  %s"),
 						PQerrorMessage(conn));
 
@@ -3216,6 +3215,20 @@ _create_event(PGconn *conn, t_configuration_options *options, int node_id, char
 							dst_ptr += strlen(dst_ptr);
 						}
 						break;
+					case 'p':
+						/* %p: former primary id ("repmgr standby switchover") */
+						src_ptr++;
+						if (event_info->former_primary_id != UNKNOWN_NODE_ID)
+						{
+							PQExpBufferData node_id;
+							initPQExpBuffer(&node_id);
+							appendPQExpBuffer(&node_id,
+											  "%i", event_info->former_primary_id);
+							strlcpy(dst_ptr, node_id.data, end_ptr - dst_ptr);
+							dst_ptr += strlen(dst_ptr);
+							termPQExpBuffer(&node_id);
+						}
+						break;
 					default:
 						/* otherwise treat the % as not special */
 						if (dst_ptr < end_ptr)

dbutils.h

@@ -174,11 +174,13 @@ typedef struct s_event_info
 {
 	char	   *node_name;
 	char	   *conninfo_str;
+	int			former_primary_id;
 } t_event_info;
 
 #define T_EVENT_INFO_INITIALIZER { \
 	NULL, \
- 	NULL \
+	NULL, \
+	UNKNOWN_NODE_ID \
 }
 
 

doc/event-notifications.sgml

@@ -63,7 +63,7 @@
    <term><option>%s</option></term>
    <listitem>
     <para>
-     success (1 or 0)
+     success (1) or failure (0)
     </para>
    </listitem>
   </varlistentry>
@@ -84,6 +84,17 @@
     </para>
    </listitem>
   </varlistentry>
+
+
+  <varlistentry>
+   <term><option>%p</option></term>
+   <listitem>
+    <para>
+     node ID of the demoted standby (<xref linkend="repmgr-standby-switchover"> only)
+    </para>
+   </listitem>
+  </varlistentry>
+
  </variablelist>
  <para>
   The values provided for <literal>%t</literal> and <literal>%d</literal>

doc/repmgr-standby-switchover.sgml

@@ -109,9 +109,14 @@
     <title>Event notifications</title>
     <para>
       <literal>standby_switchover</literal> and <literal>standby_promote</literal>
-      <link linkend="event-notifications">event notification</link> will be generated for the new primary,
+      <link linkend="event-notifications">event notifications</link> will be generated for the new primary,
       and a <literal>node_rejoin</literal> event notification for the former primary (new standby).
     </para>
+    <para>
+      If using an event notification script, <literal>standby_switchover</literal>
+      will populate the placeholder parameter <literal>%p</literal> with the node ID of
+      the former standby.
+    </para>
   </refsect1>
 
 

repmgr-action-standby.c

@@ -2016,6 +2016,8 @@ do_standby_switchover(void)
 	NodeInfoList sibling_nodes = T_NODE_INFO_LIST_INITIALIZER;
 	int			unreachable_sibling_node_count = 0;
 
+	t_event_info event_info = T_EVENT_INFO_INITIALIZER;
+
 	/*
 	 * SANITY CHECKS
 	 *
@@ -2114,6 +2116,8 @@ do_standby_switchover(void)
 
 	log_verbose(LOG_DEBUG, "remote node name is \"%s\"", remote_node_record.node_name);
 
+	/* this will fill the %p event notification parameter */
+	event_info.former_primary_id = remote_node_record.node_id;
 
 	/*
 	 * If --force-rewind specified, check pg_rewind can be used, and
@@ -2790,8 +2794,7 @@ do_standby_switchover(void)
 	log_debug("executing:\n  %s", remote_command_str.data);
 	initPQExpBuffer(&command_output);
 
-	command_success = remote_command(
-									 remote_host,
+	command_success = remote_command(remote_host,
 									 runtime_options.remote_user,
 									 remote_command_str.data,
 									 &command_output);
@@ -2807,12 +2810,13 @@ do_standby_switchover(void)
 		if (strlen(command_output.data) > 2)
 			log_detail("%s", command_output.data);
 
-		create_event_record(local_conn,
-							&config_file_options,
-							config_file_options.node_id,
-							"standby_switchover",
-							false,
-							command_output.data);
+		create_event_notification_extended(local_conn,
+										   &config_file_options,
+										   config_file_options.node_id,
+										   "standby_switchover",
+										   false,
+										   command_output.data,
+										   &event_info);
 	}
 	else
 	{
@@ -2825,12 +2829,13 @@ do_standby_switchover(void)
 						  config_file_options.node_id,
 						  remote_node_record.node_id);
 
-		create_event_record(local_conn,
-							&config_file_options,
-							config_file_options.node_id,
-							"standby_switchover",
-							true,
-							event_details.data);
+		create_event_notification_extended(local_conn,
+										   &config_file_options,
+										   config_file_options.node_id,
+										   "standby_switchover",
+										   true,
+										   event_details.data,
+										   &event_info);
 		termPQExpBuffer(&event_details);
 	}
 
@@ -3730,8 +3735,7 @@ initialise_direct_clone(t_node_info *node_record)
 		{
 			log_error("%s", event_details.data);
 
-			create_event_notification(
-									  primary_conn,
+			create_event_notification(primary_conn,
 									  &config_file_options,
 									  config_file_options.node_id,
 									  "standby_clone",