MySQL 8.0 Reference Manual Including MySQL NDB Cluster 8.0

21.2.6 Adopting a Group Replication Deployment

If you have an existing deployment of Group Replication and you want to use it to create a cluster, pass the adoptFromGR option to the dba.createCluster() function. The created InnoDB cluster matches whether the replication group is running as single-primary or multi-primary.

To adopt an existing Group Replication group, connect to a group member using MySQL Shell. In the following example a single-primary group is adopted. We connect to gr-member-2, a secondary instance, while gr-member-1 is functioning as the group's primary. Create a cluster using dba.createCluster(), passing in the adoptFromGR option. For example:

  
mysql-js> var cluster = dba.createCluster('prodCluster', {adoptFromGR: true});

A new InnoDB cluster will be created on instance 'root@gr-member-2:3306'.

Creating InnoDB cluster 'prodCluster' on 'root@gr-member-2:3306'...
Adding Seed Instance...

Cluster successfully created. Use cluster.addInstance() to add MySQL instances.
At least 3 instances are needed for the cluster to be able to withstand up to
one server failure.
	
Tip

If the instance has super_read_only=ON then you might need to confirm that AdminAPI can set super_read_only=OFF. See Super Read-only and Instances for more information.

The new cluster matches the mode of the group. If the adopted group was running in single-primary mode then a single-primary cluster is created. If the adopted group was running in multi-primary mode then a multi-primary cluster is created.