On nodedb2

mysql> SET @@GLOBAL.group_replication_group_name='aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee';
mysql> SET @@GLOBAL.group_replication_local_address='nodedb2:33061';
mysql> SET @@GLOBAL.group_replication_group_seeds='nodedb1:33061,nodedb2:33061,nodedb3:33061';
mysql>  SET @@GLOBAL.group_replication_bootstrap_group=0;
mysql> SET @@global.group_replication_recovery_retry_count=5;
mysql> change master to master_user='repl' for channel 'group_replication_recovery';
mysql> START GROUP_REPLICATION;
mysql> SELECT * FROM performance_schema.replication_group_members;