From 65d355c7d70b830006384b7da1f84b90dd465e12 Mon Sep 17 00:00:00 2001
From: Johan Wikman <johan.wikman@mariadb.com>
Date: Tue, 4 Sep 2018 12:55:07 +0300
Subject: [PATCH] MXS-2011 Enforce gtid based replication

If secondary masters are defined, MASTER_USE_GTID=Slave_pos must
be specified for the default master.

If MASTER_USE_GTID is specified, only Slave_pos is allowed as
value.
---
 .../modules/routing/binlogrouter/blr_slave.cc | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/server/modules/routing/binlogrouter/blr_slave.cc b/server/modules/routing/binlogrouter/blr_slave.cc
index 233e3a533..369d5fcd6 100644
--- a/server/modules/routing/binlogrouter/blr_slave.cc
+++ b/server/modules/routing/binlogrouter/blr_slave.cc
@@ -4540,6 +4540,21 @@ int blr_handle_change_master(ROUTER_INSTANCE* router,
         return -1;
     }
 
+    if (index != 0)
+    {
+        string use_gtid = router->configs[0].use_mariadb10_gtid;
+
+        if (use_gtid.empty() || (strcasecmp(use_gtid.c_str(), "slave_pos") != 0))
+        {
+            static const char MESSAGE[] =
+                "Secondary masters can only be used in conjunction with GTID based replication. "
+                "Specify MASTER_USE_GTID=Slave_pos for the default master connection.";
+            mxb_assert(sizeof(MESSAGE) <= BINLOG_ERROR_MSG_LEN);
+            strcpy(error, MESSAGE);
+            return -1;
+        }
+    }
+
     std::vector<char> cmd_string(command, command + strlen(command) + 1); // Include the NULL
 
     /* Parse SQL command and populate the change_master struct */
@@ -4572,6 +4587,17 @@ int blr_handle_change_master(ROUTER_INSTANCE* router,
         return -1;
     }
 
+    string use_gtid = options.use_mariadb10_gtid;
+
+    if (!use_gtid.empty() && (strcasecmp(use_gtid.c_str(), "slave_pos") != 0))
+    {
+        static const char MESSAGE[] =
+            "Only MASTER_USE_GTID=Slave_pos is allowed.";
+        mxb_assert(sizeof(MESSAGE) <= BINLOG_ERROR_MSG_LEN);
+        strcpy(error, MESSAGE);
+        return -1;
+    }
+
     ChangeMasterConfig config;
     if (!options.validate(router, error, &config))
     {