From a0f02e454c0248f9f15d8740f8b7c68e3f6a41a5 Mon Sep 17 00:00:00 2001
From: Ian Barwick <ian@2ndquadrant.com>
Date: Fri, 1 Jul 2016 09:42:55 +0900
Subject: [PATCH] repmgr: during switchover check demotion candidate's pidfile

If the pidfile is still there after apparent shutdown, or we're
unable to access the server at all, something has gone wrong and
the switchover should be aborted.
---
 repmgr.c | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/repmgr.c b/repmgr.c
index 6c9761ac..73e0ddfb 100644
--- a/repmgr.c
+++ b/repmgr.c
@@ -2751,7 +2751,7 @@ do_standby_switchover(void)
 	int			server_version_num;
 	bool		use_pg_rewind;
 
-	/* the remote server is the primary which will be demoted */
+	/* the remote server is the primary to be demoted */
 	char	    remote_conninfo[MAXCONNINFO] = "";
 	char	    remote_host[MAXLEN];
 	char        remote_data_directory[MAXLEN];
@@ -3200,16 +3200,38 @@ do_standby_switchover(void)
 		/* database server could not be contacted */
 		if (ping_res == PQPING_NO_RESPONSE)
 		{
+			bool command_success;
+
 			/*
-			 * XXX here we should directly access the server and check that the
+			 * directly access the server and check that the
 			 * pidfile has gone away so we can be sure the server is actually
 			 * shut down and the PQPING_NO_RESPONSE is not due to other issues
 			 * such as coincidental network failure.
 			 */
-			shutdown_success = true;
+			initPQExpBuffer(&command_output);
 
-			log_notice(_("current master has been stopped\n"));
-			break;
+			maxlen_snprintf(command,
+					"ls %s/postmaster.pid >/dev/null 2>&1 && echo 1 || echo 0",
+					remote_data_directory);
+
+			command_success = remote_command(
+				remote_host,
+				runtime_options.remote_user,
+				command,
+				&command_output);
+
+			if (command_success == true && *command_output.data == '0')
+			{
+				shutdown_success = true;
+
+				log_notice(_("current master has been stopped\n"));
+
+				termPQExpBuffer(&command_output);
+
+				break;
+			}
+
+			termPQExpBuffer(&command_output);
 		}
 
 		/* XXX make configurable? */