From 654b5f1958b67d6158f93184a58b09765036d149 Mon Sep 17 00:00:00 2001
From: Esa Korhonen <esa.korhonen@mariadb.com>
Date: Wed, 16 May 2018 10:44:59 +0300
Subject: [PATCH] MXS-1865 Wrong permissions on backends no longer cause
 monitor start to fail

The logic was weird, as the permission checking function assumes a disconnected
server as fine. The checking is now done when starting the main loop and lacking
grants print errors but does not stop the monitor.
---
 .../modules/monitor/mariadbmon/mariadbmon.cc  | 22 ++++++++++---------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/server/modules/monitor/mariadbmon/mariadbmon.cc b/server/modules/monitor/mariadbmon/mariadbmon.cc
index 86e47b3dd..8852b9fb4 100644
--- a/server/modules/monitor/mariadbmon/mariadbmon.cc
+++ b/server/modules/monitor/mariadbmon/mariadbmon.cc
@@ -160,20 +160,12 @@ bool MariaDBMonitor::start(const MXS_CONFIG_PARAMETER* params)
         error = true;
     }
 
-    if (!error && !check_monitor_permissions(m_monitor_base, "SHOW SLAVE STATUS"))
+    if (!error && (thread_start(&m_thread, monitorMain, this, 0) == NULL))
     {
+        MXS_ERROR("Failed to start monitor thread for monitor '%s'.", m_monitor_base->name);
         error = true;
     }
 
-    if (!error)
-    {
-        if (thread_start(&m_thread, monitorMain, this, 0) == NULL)
-        {
-            MXS_ERROR("Failed to start monitor thread for monitor '%s'.", m_monitor_base->name);
-            error = true;
-        }
-    }
-
     if (error)
     {
         MXS_ERROR("Failed to start monitor. See earlier errors for more information.");
@@ -339,6 +331,16 @@ void MariaDBMonitor::main_loop()
         check_maxscale_schema_replication();
     }
 
+    /* Check monitor permissions. Failure won't cause the monitor to stop. Afterwards, close connections so
+     * that update_server() reconnects and checks server version. TODO: check permissions when checking
+     * server version. */
+    check_monitor_permissions(m_monitor_base, "SHOW SLAVE STATUS");
+    for (auto iter = m_servers.begin(); iter != m_servers.end(); iter++)
+    {
+        mysql_close((*iter)->m_server_base->con);
+        (*iter)->m_server_base->con = NULL;
+    }
+
     while (m_keep_running)
     {
         timespec loop_start;