"cluster show": improve handling of database errors

In particular, if running "repmgr cluster show" against a database
without the repmgr metadata, showing the error (rather than just
"no records found" etc.) will provide some clues about the problem.

HISTORY

@@ -4,6 +4,7 @@
         repmgr: improve switchover log messages and exit code when old primary could
           not be shut down cleanly (Ian)
         repmgr: add --dry-run mode to "repmgr standby follow"; GitHub #368 (Ian)
+        repmgr: fix upstream node display in "repmgr node status"; GitHub #363 (fanf2)
 
 4.0.2   2018-01-18
         repmgr: add missing -W option to getopt_long() invocation; GitHub #350 (Ian)

dbutils.c

@@ -2123,7 +2123,11 @@ get_node_records_by_priority(PGconn *conn, NodeInfoList *node_list)
 	return;
 }
 
-void
+/*
+ * return all node records together with their upstream's node name,
+ * if available.
+ */
+bool
 get_all_node_records_with_upstream(PGconn *conn, NodeInfoList *node_list)
 {
 	PQExpBufferData query;
@@ -2145,11 +2149,19 @@ get_all_node_records_with_upstream(PGconn *conn, NodeInfoList *node_list)
 
 	termPQExpBuffer(&query);
 
+	if (PQresultStatus(res) != PGRES_TUPLES_OK)
+	{
+		log_error(_("unable to retrieve node records"));
+		log_detail("%s", PQerrorMessage(conn));
+		PQclear(res);
+		return false;
+	}
+
 	_populate_node_records(res, node_list);
 
 	PQclear(res);
 
-	return;
+	return true;
 }
 
 
@@ -2271,9 +2283,11 @@ _create_update_node_record(PGconn *conn, char *action, t_node_info *node_info)
 
 	if (PQresultStatus(res) != PGRES_COMMAND_OK)
 	{
-		log_error(_("unable to %s node record:\n  %s"),
+		log_error(_("unable to %s node record for node \"%s\" (ID: %i)"),
 				  action,
-				  PQerrorMessage(conn));
+				  node_info->node_name,
+				  node_info->node_id);
+		log_detail("%s", PQerrorMessage(conn));
 		PQclear(res);
 		return false;
 	}

dbutils.h

@@ -410,7 +410,7 @@ void		get_all_node_records(PGconn *conn, NodeInfoList *node_list);
 void		get_downstream_node_records(PGconn *conn, int node_id, NodeInfoList *nodes);
 void		get_active_sibling_node_records(PGconn *conn, int node_id, int upstream_node_id, NodeInfoList *node_list);
 void		get_node_records_by_priority(PGconn *conn, NodeInfoList *node_list);
-void		get_all_node_records_with_upstream(PGconn *conn, NodeInfoList *node_list);
+bool		get_all_node_records_with_upstream(PGconn *conn, NodeInfoList *node_list);
 
 bool		create_node_record(PGconn *conn, char *repmgr_action, t_node_info *node_info);
 bool		update_node_record(PGconn *conn, char *repmgr_action, t_node_info *node_info);

repmgr-action-cluster.c

@@ -82,6 +82,7 @@ do_cluster_show(void)
 	NodeInfoListCell *cell = NULL;
 	int			i = 0;
 	ItemList	warnings = {NULL, NULL};
+	bool		success = false;
 
 	/* Connect to local database to obtain cluster connection data */
 	log_verbose(LOG_INFO, _("connecting to database"));
@@ -91,11 +92,19 @@ do_cluster_show(void)
 	else
 		conn = establish_db_connection_by_params(&source_conninfo, true);
 
-	get_all_node_records_with_upstream(conn, &nodes);
+	success = get_all_node_records_with_upstream(conn, &nodes);
+
+	if (success == false)
+	{
+		/* get_all_node_records_with_upstream() will print error message */
+		PQfinish(conn);
+		exit(ERR_BAD_CONFIG);
+	}
 
 	if (nodes.node_count == 0)
 	{
-		log_error(_("unable to retrieve any node records"));
+		log_error(_("no node records were found"));
+		log_hint(_("ensure at least one node is registered"));
 		PQfinish(conn);
 		exit(ERR_BAD_CONFIG);
 	}