MySQL 8.0 Reference Manual Including MySQL NDB Cluster 8.0 START GROUP_REPLICATION Statement

          [, PASSWORD='user_pass']
          [, DEFAULT_AUTH='plugin_name']

Starts group replication. This statement requires the GROUP_REPLICATION_ADMIN privilege (or the deprecated SUPER privilege). If super_read_only=ON is set and the member should join as a primary, super_read_only is set to OFF once Group Replication successfully starts.

From MySQL 8.0.21, you can specify user credentials for distributed recovery on the START GROUP_REPLICATION statement using the USER, PASSWORD, and DEFAULT_AUTH options, as follows:

These credentials are used for distributed recovery on the group_replication_recovery channel. When you specify user credentials on START GROUP_REPLICATION, the credentials are saved in memory only, and are removed by a STOP GROUP_REPLICATION statement or server shutdown. You must issue a START GROUP_REPLICATION statement to provide the credentials again. This method is therefore not compatible with starting Group Replication automatically on server start, as specified by the group_replication_start_on_boot system variable.

User credentials specified on START GROUP_REPLICATION take precedence over any user credentials set for the group_replication_recovery channel using a CHANGE REPLICATION SOURCE TO statement (from MySQL 8.0.23) or CHANGE MASTER TO statement (before MySQL 8.0.23). Note that user credentials set using these statements are stored in the replication metadata repositories, and are used when START GROUP_REPLICATION is specified without user credentials, including automatic starts if the group_replication_start_on_boot system variable is set to ON. To gain the security benefits of specifying user credentials on START GROUP_REPLICATION, ensure that group_replication_start_on_boot is set to OFF (the default is ON), and clear any user credentials previously set for the group_replication_recovery channel, following the instructions in Section 18.5.3, “Securing Distributed Recovery Connections”.