MDEV-6699 : wsrep_node_name not automatically set to hostname

Fixed by using hostname (glob_hostname) as default value for
wsrep_node_name system variable.
Added a test case.

mysql-test/suite/sys_vars/r/wsrep_node_name_basic.result

@@ -4,10 +4,10 @@
 call mtr.add_suppression("WSREP: Failed to get provider options");
 # save the initial value
 SET @wsrep_node_name_global_saved = @@global.wsrep_node_name;
-# default
-SELECT @@global.wsrep_node_name;
-@@global.wsrep_node_name
-
+# default (expect 1)
+SELECT COUNT(@@global.wsrep_node_name);
+COUNT(@@global.wsrep_node_name)
+1
 
 # scope
 SELECT @@session.wsrep_node_name;
@@ -27,21 +27,34 @@ SELECT @@global.wsrep_node_name;
 @@global.wsrep_node_name
 hyphenated-node-name
 SET @@global.wsrep_node_name=default;
-SELECT @@global.wsrep_node_name;
-@@global.wsrep_node_name
-
+# default (expect 1)
+SELECT COUNT(@@global.wsrep_node_name);
+COUNT(@@global.wsrep_node_name)
+1
 
 # invalid values
 SET @@global.wsrep_node_name=NULL;
 ERROR 42000: Variable 'wsrep_node_name' can't be set to the value of 'NULL'
-SELECT @@global.wsrep_node_name;
-@@global.wsrep_node_name
-
+SELECT COUNT(@@global.wsrep_node_name);
+COUNT(@@global.wsrep_node_name)
+1
 SET @@global.wsrep_node_name=1;
 ERROR 42000: Incorrect argument type to variable 'wsrep_node_name'
-SELECT @@global.wsrep_node_name;
-@@global.wsrep_node_name
-
+SELECT COUNT(@@global.wsrep_node_name);
+COUNT(@@global.wsrep_node_name)
+1
+#
+# MDEV-6699 : wsrep_node_name not automaticly set to hostname
+#
+SET @@global.wsrep_node_name=default;
+SELECT @@GLOBAL.wsrep_node_name = VARIABLE_VALUE FROM
+INFORMATION_SCHEMA.GLOBAL_VARIABLES WHERE VARIABLE_NAME='hostname';
+@@GLOBAL.wsrep_node_name = VARIABLE_VALUE
+1
+SELECT @@GLOBAL.wsrep_node_name = VARIABLE_VALUE FROM
+INFORMATION_SCHEMA.GLOBAL_VARIABLES WHERE VARIABLE_NAME='wsrep_node_name';
+@@GLOBAL.wsrep_node_name = VARIABLE_VALUE
+1
 
 # restore the initial value
 SET @@global.wsrep_node_name = @wsrep_node_name_global_saved;

mysql-test/suite/sys_vars/t/wsrep_node_name_basic.test

@@ -9,8 +9,8 @@ call mtr.add_suppression("WSREP: Failed to get provider options");
 --echo # save the initial value
 SET @wsrep_node_name_global_saved = @@global.wsrep_node_name;
 
---echo # default
-SELECT @@global.wsrep_node_name;
+--echo # default (expect 1)
+SELECT COUNT(@@global.wsrep_node_name);
 
 --echo
 --echo # scope
@@ -26,16 +26,26 @@ SELECT @@global.wsrep_node_name;
 SET @@global.wsrep_node_name='hyphenated-node-name';
 SELECT @@global.wsrep_node_name;
 SET @@global.wsrep_node_name=default;
-SELECT @@global.wsrep_node_name;
+--echo # default (expect 1)
+SELECT COUNT(@@global.wsrep_node_name);
 
 --echo
 --echo # invalid values
 --error ER_WRONG_VALUE_FOR_VAR
 SET @@global.wsrep_node_name=NULL;
-SELECT @@global.wsrep_node_name;
+SELECT COUNT(@@global.wsrep_node_name);
 --error ER_WRONG_TYPE_FOR_VAR
 SET @@global.wsrep_node_name=1;
-SELECT @@global.wsrep_node_name;
+SELECT COUNT(@@global.wsrep_node_name);
+
+--echo #
+--echo # MDEV-6699 : wsrep_node_name not automaticly set to hostname
+--echo #
+SET @@global.wsrep_node_name=default;
+SELECT @@GLOBAL.wsrep_node_name = VARIABLE_VALUE FROM
+INFORMATION_SCHEMA.GLOBAL_VARIABLES WHERE VARIABLE_NAME='hostname';
+SELECT @@GLOBAL.wsrep_node_name = VARIABLE_VALUE FROM
+INFORMATION_SCHEMA.GLOBAL_VARIABLES WHERE VARIABLE_NAME='wsrep_node_name';
 
 --echo
 --echo # restore the initial value

sql/mysqld.cc

@@ -3705,13 +3705,6 @@ static int init_common_variables()
   }
   else
     opt_log_basename= glob_hostname;
-#ifdef WITH_WSREP
-  if (0 == wsrep_node_name || 0 == wsrep_node_name[0])
-  {
-    my_free((void *)wsrep_node_name);
-    wsrep_node_name= my_strdup(glob_hostname, MYF(MY_WME));
-  }
-#endif /* WITH_WSREP */
   if (!*pidfile_name)
   {
     strmake(pidfile_name, opt_log_basename, sizeof(pidfile_name)-5);

sql/sys_vars.cc

@@ -3731,7 +3731,7 @@ static Sys_var_charptr Sys_wsrep_cluster_address (
 static Sys_var_charptr Sys_wsrep_node_name (
        "wsrep_node_name", "Node name",
        PREALLOCATED GLOBAL_VAR(wsrep_node_name), CMD_LINE(REQUIRED_ARG),
-       IN_FS_CHARSET, DEFAULT(""), NO_MUTEX_GUARD, NOT_IN_BINLOG,
+       IN_FS_CHARSET, DEFAULT(glob_hostname), NO_MUTEX_GUARD, NOT_IN_BINLOG,
        wsrep_node_name_check, wsrep_node_name_update);
 
 static Sys_var_charptr Sys_wsrep_node_address (