From cfd35852b75864ec99eb45a948c55f12cb3d4105 Mon Sep 17 00:00:00 2001
From: Ian Barwick <ian@2ndquadrant.com>
Date: Wed, 15 Apr 2020 14:00:50 +0900
Subject: [PATCH] standby switchover: improve archive check error handling

Explicitly log if a database connection failure caused the check
to fail.

It's unlikely this situation will be encountered, as the data directory
check will already have run and checked for connection failure, however
there's a small chance the connection could fail between checks.
---
 repmgr-action-node.c    |  1 -
 repmgr-action-standby.c | 27 +++++++++++++++++++++------
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/repmgr-action-node.c b/repmgr-action-node.c
index 49b8a62c..0b5ae0e3 100644
--- a/repmgr-action-node.c
+++ b/repmgr-action-node.c
@@ -806,7 +806,6 @@ do_node_check(void)
 	{
 		exit_optformat_error("DB_CONNECTION",
 							 ERR_DB_CONN);
-
 	}
 
 	if (get_node_record(conn, config_file_options.node_id, &node_info) != RECORD_FOUND)
diff --git a/repmgr-action-standby.c b/repmgr-action-standby.c
index 9f6a24bf..eb81edbc 100644
--- a/repmgr-action-standby.c
+++ b/repmgr-action-standby.c
@@ -132,7 +132,7 @@ static void sibling_nodes_follow(t_node_info *local_node_record, NodeInfoList *s
 static t_remote_error_type parse_remote_error(const char *error);
 
 static NodeStatus parse_node_status_is_shutdown_cleanly(const char *node_status_output, XLogRecPtr *checkPoint);
-static CheckStatus parse_node_check_archiver(const char *node_check_output, int *files, int *threshold);
+static CheckStatus parse_node_check_archiver(const char *node_check_output, int *files, int *threshold, t_remote_error_type *remote_error);
 static ConnectionStatus parse_remote_node_replication_connection(const char *node_check_output);
 static bool parse_data_directory_config(const char *node_check_output, t_remote_error_type *remote_error);
 static bool parse_replication_config_owner(const char *node_check_output);
@@ -4054,7 +4054,6 @@ do_standby_switchover(void)
 	{
 		t_remote_error_type remote_error = REMOTE_ERROR_NONE;
 
-
 		if (parse_data_directory_config(command_output.data, &remote_error) == false)
 		{
 			if (remote_error != REMOTE_ERROR_NONE)
@@ -4273,6 +4272,7 @@ do_standby_switchover(void)
 		{
 			int			files = 0;
 			int			threshold = 0;
+			t_remote_error_type remote_error = REMOTE_ERROR_NONE;
 
 			initPQExpBuffer(&remote_command_str);
 			make_remote_repmgr_path(&remote_command_str, &remote_node_record);
@@ -4291,7 +4291,7 @@ do_standby_switchover(void)
 
 			if (command_success == true)
 			{
-				status = parse_node_check_archiver(command_output.data, &files, &threshold);
+				status = parse_node_check_archiver(command_output.data, &files, &threshold, &remote_error);
 			}
 
 			termPQExpBuffer(&command_output);
@@ -4300,11 +4300,18 @@ do_standby_switchover(void)
 			{
 				case CHECK_STATUS_UNKNOWN:
 					{
-						if (runtime_options.force == false)
+						if (runtime_options.force == false || remote_error == REMOTE_ERROR_DB_CONNECTION)
 						{
 							log_error(_("unable to check number of pending archive files on demotion candidate \"%s\""),
 									  remote_node_record.node_name);
-							log_hint(_("use -F/--force to continue anyway"));
+
+							if (remote_error == REMOTE_ERROR_DB_CONNECTION)
+								log_detail(_("an error was encountered when attempting to connect to PostgreSQL on node \"%s\" (ID: %i)"),
+										   remote_node_record.node_name,
+										   remote_node_record.node_id);
+							else
+								log_hint(_("use -F/--force to continue anyway"));
+
 							PQfinish(remote_conn);
 							PQfinish(local_conn);
 
@@ -8381,7 +8388,7 @@ parse_remote_node_replication_connection(const char *node_check_output)
 
 
 static CheckStatus
-parse_node_check_archiver(const char *node_check_output, int *files, int *threshold)
+parse_node_check_archiver(const char *node_check_output, int *files, int *threshold, t_remote_error_type *remote_error)
 {
 	CheckStatus status = CHECK_STATUS_UNKNOWN;
 
@@ -8396,6 +8403,7 @@ parse_node_check_archiver(const char *node_check_output, int *files, int *thresh
 		{"status", required_argument, NULL, 'S'},
 		{"files", required_argument, NULL, 'f'},
 		{"threshold", required_argument, NULL, 't'},
+		{"error", required_argument, NULL, 'E'},
 		{NULL, 0, NULL, 0}
 	};
 
@@ -8456,6 +8464,12 @@ parse_node_check_archiver(const char *node_check_output, int *files, int *thresh
 					}
 				}
 				break;
+			case 'E':
+				{
+					*remote_error = parse_remote_error(optarg);
+					status = CHECK_STATUS_UNKNOWN;
+				}
+				break;
 		}
 	}
 
@@ -8464,6 +8478,7 @@ parse_node_check_archiver(const char *node_check_output, int *files, int *thresh
 	return status;
 }
 
+
 static bool
 parse_data_directory_config(const char *node_check_output, t_remote_error_type *remote_error)
 {