revert previous change

Author: linyudoa

src/azure-cli/azure/cli/command_modules/mysql/custom.py

@@ -19,7 +19,7 @@
 from azure.cli.core.util import CLIError, sdk_no_wait, user_confirmation, run_cmd
 from azure.cli.core.local_context import ALL
 from azure.mgmt.mysqlflexibleservers import models
-from azure.cli.core.azclierror import ClientRequestError, RequiredArgumentMissingError, InvalidArgumentValueError, ValidationError
+from azure.cli.core.azclierror import ClientRequestError, ArgumentUsageError, RequiredArgumentMissingError, InvalidArgumentValueError, ValidationError
 from ._client_factory import get_mysql_flexible_management_client, cf_mysql_flexible_firewall_rules, cf_mysql_flexible_db, \
     cf_mysql_check_resource_availability, cf_mysql_check_resource_availability_without_location, cf_mysql_flexible_config, \
     cf_mysql_flexible_servers, cf_mysql_flexible_replica, cf_mysql_flexible_adadmin, cf_mysql_flexible_private_dns_zone_suffix_operations, cf_mysql_servers, \
@@ -1175,6 +1175,10 @@ def server_delete_func(cmd, client, resource_group_name, server_name, yes=None):
 
 
 def flexible_server_restart(cmd, client, resource_group_name, server_name, fail_over=None):
+    instance = client.get(resource_group_name, server_name)
+    if fail_over is not None and instance.high_availability.mode != "ZoneRedundant":
+        raise ArgumentUsageError("Failing over can only be triggered for zone redundant servers.")
+
     if fail_over is not None:
         if fail_over != 'Forced':
             raise InvalidArgumentValueError("Allowed failover parameters are 'Forced'.")