According to MYSQL 5.7 Reference Manual :
http://dev.mysql.com/doc/refman/5.7/en/group-replication-find-primary.html
http://dev.mysql.com/doc/refman/5.7/en/group-replication-monitoring.html
We can use the sql below to find the primary-node's hostname when group replication is deployed in single-mode :
mysql> SELECT * FROM performance_schema.replication_group_members WHERE MEMBER_ID = (SELECT VARIABLE_VALUE FROM performance_schema.global_status WHERE VARIABLE_NAME= 'group_replication_primary_member');
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 9176f4d3-c7f6-11e6-bcf7-fa163ee40410 | myhost | 24801 | ONLINE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
1 row in set (0.00 sec)
the question is : How to get ip address instead of hostname ?