AdminAPI provides the dba.configureInstance() function that checks if an instance is suitably configured for InnoDB Cluster usage, and configures the instance if it finds any settings which are not compatible with InnoDB Cluster. You run the dba.configureInstance() command against an instance and it checks all of the settings required to enable the instance to be used for InnoDB Cluster usage. If the instance does not require configuration changes, there is no need to modify the configuration of the instance, and the dba.configureInstance() command output confirms that the instance is ready for InnoDB Cluster usage. If any changes are required to make the instance compatible with InnoDB Cluster, a report of the incompatible settings is displayed, and you can choose to let the command make the changes to the instance's option file. Depending on the way MySQL Shell is connected to the instance, and the version of MySQL running on the instance, you can make these changes permanent by persisting them to a remote instance's option file, see Persisting Settings. Instances which do not support persisting configuration changes automatically require that you configure the instance locally, see Configuring Instances with dba.configureLocalInstance(). Alternatively you can make the changes to the instance's option file manually, see Using Option Files for more information. Regardless of the way you make the configuration changes, you might have to restart MySQL to ensure the configuration changes are detected.

The syntax of the dba.configureInstance() command is:

dba.configureInstance([instance][, options])

where instance is an instance definition, and options is a data dictionary with additional options to configure the operation. The command returns a descriptive text message about the operation's result.

The instance definition is the connection data for the instance, see Connecting to the Server Using URI-Like Strings or Key-Value Pairs. If the target instance already belongs to an InnoDB Cluster an error is generated and the process fails.

The options dictionary can contain the following:

Although the connection password can be contained in the instance definition, this is insecure and not recommended. Use the MySQL Shell Section 4.4, “Pluggable Password Store” to store instace passwords securely.

Once dba.configureInstance() is issued against an instance, the command checks if the instance's settings are suitable for InnoDB Cluster usage. A report is displayed which shows the settings required by InnoDB Cluster . If the instance does not require any changes to its settings you can use it in an InnoDB Cluster, and can proceed to Creating the Cluster. If the instance's settings are not valid for InnoDB Cluster usage the dba.configureInstance() command displays the settings which require modification. Before configuring the instance you are prompted to confirm the changes shown in a table with the following information:

How you proceed depends on whether the instance supports persisting settings, see Persisting Settings. When dba.configureInstance() is issued against the MySQL instance which MySQL Shell is currently running on, in other words the local instance, it attempts to automatically configure the instance. When dba.configureInstance() is issued against a remote instance, if the instance supports persisting configuration changes automatically, you can choose to do this. If a remote instance does not support persisting the changes to configure it for InnoDB Cluster usage, you have to configure the instance locally. See Configuring Instances with dba.configureLocalInstance().

In general, a restart of the instance is not required after dba.configureInstance() configures the option file, but for some specific settings a restart might be required. This information is shown in the report generated after issuing dba.configureInstance(). If the instance supports the RESTART statement, MySQL Shell can shutdown and then start the instance. This ensures that the changes made to the instance's option file are detected by mysqld. For more information see RESTART.

The dba.configureInstance() method verifies that a suitable user is available for cluster usage, which is used for connections between members of the cluster, see Creating User Accounts for Administration.

If you do not specify a user to administer the cluster, in interactive mode a wizard enables you to choose one of the following options:

Once you have prepared your instances, use the dba.createCluster() function to create the cluster, using the instance which MySQL Shell is connected to as the seed instance for the cluster. The seed instance is replicated to the other instances that you add to the cluster, making them replicas of the seed instance. In this procedure the ic-1 instance is used as the seed. When you issue dba.createCluster(name) MySQL Shell creates a classic MySQL protocol session to the server instance connected to the MySQL Shell's current global session. For example, to create a cluster called testCluster and assign the returned cluster to a variable called cluster:

mysql-js> var cluster = dba.createCluster('testCluster')
Validating instance at icadmin@ic-1:3306...
This instance reports its own address as ic-1
Instance configuration is suitable.
Creating InnoDB cluster 'testCluster' on 'icadmin@ic-1:3306'...
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.

This pattern of assigning the returned cluster to a variable enables you to then execute further operations against the cluster using the Cluster object's methods. The returned Cluster object uses a new session, independent from the MySQL Shell's global session. This ensures that if you change the MySQL Shell global session, the Cluster object maintains its session to the instance.

To be able to administer a cluster, you must ensure that you have a suitable user which has the required privileges. The recommended approach is to create an administration user. If you did not create an administration user when configuring your instances, use the Cluster.setupAdminAccount() operation. For example to create a user named icadmin that can administer the InnoDB Cluster assigned to the variable cluster, issue:

mysql-js> cluster.setupAdminAccount(icadmin)

See Configuring Users for AdminAPI for more information on cluster administration users.

The dba.createCluster() operation supports MySQL Shell's interactive option. When interactive is on, prompts appear in the following situations:

To check the cluster has been created, use the cluster instance's status() function. See Checking a cluster's Status with Cluster.status().

When you create a cluster using MySQL Shell 8.0.14 and later, you can set the timeout before instances are expelled from the cluster, for example when they become unreachable. Pass the expelTimeout option to the dba.createCluster() operation, which configures the group_replication_member_expel_timeout variable on the seed instance. The expelTimeout option can take an integer value in the range of 0 to 3600. All instances running MySQL server 8.0.13 and later which are added to a cluster with expelTimeout configured are automatically configured to have the same expelTimeout value as configured on the seed instance.

For information on the other options which you can pass to dba.createCluster(), see Section 6.2.5, “Working with InnoDB Cluster”.

Use the Cluster.addInstance(instance) function to add more instances to the cluster, where instance is connection information to a configured instance, see Configuring Production Instances. From version 8.0.17, Group Replication implements compatibility policies which consider the patch version of the instances, and the Cluster.addInstance() operation detects this and in the event of an incompatibility the operation terminates with an error. See Checking the MySQL Version on Instances and Combining Different Member Versions in a Group

You need a minimum of three instances in the cluster to make it tolerant to the failure of one instance. Adding further instances increases the tolerance to failure of an instance. To add an instance to the cluster issue:

mysql-js> cluster.addInstance('icadmin@ic-2:3306')
A new instance will be added to the InnoDB cluster. Depending on the amount of
data on the cluster this might take from a few seconds to several hours.
Please provide the password for 'icadmin@ic-2:3306': ********
Adding instance to the cluster ...
Validating instance at ic-2:3306...
This instance reports its own address as ic-2
Instance configuration is suitable.
The instance 'icadmin@ic-2:3306' was successfully added to the cluster.

When a new instance is added to the cluster, the local address for this instance is automatically added to the group_replication_group_seeds variable on all online cluster instances in order to allow them to use the new instance to rejoin the group, if needed.

If you are using MySQL 8.0.17 or later you can choose how the instance recovers the transactions it requires to synchronize with the cluster. Only when the joining instance has recovered all of the transactions previously processed by the cluster can it then join as an online instance and begin processing transactions. For more information, see Section 6.2.2.2, “Using MySQL Clone with InnoDB Cluster”.

Also in 8.0.17 and later, you can configure how Cluster.addInstance() behaves, letting recovery operations proceed in the background or monitoring different levels of progress in MySQL Shell.

Depending on which option you chose to recover the instance from the cluster, you see different output in MySQL Shell. Suppose that you are adding the instance ic-2 to the cluster, and ic-1 is the seed or donor.

To cancel the monitoring of the recovery phase, issue CONTROL+C. This stops the monitoring but the recovery process continues in the background. The waitRecovery integer option can be used with the Cluster.addInstance() operation to control the behavior of the command regarding the recovery phase. The following values are accepted:

By default, if the standard output which MySQL Shell is running on refers to a terminal, the waitRecovery option defaults to 3. Otherwise, it defaults to 2. See Monitoring Recovery Operations.

To verify the instance has been added, use the cluster instance's status() function. For example this is the status output of a sandbox cluster after adding a second instance:

mysql-js> cluster.status()
{
    "clusterName": "testCluster",
    "defaultReplicaSet": {
        "name": "default",
        "primary": "ic-1:3306",
        "ssl": "REQUIRED",
        "status": "OK_NO_TOLERANCE",
        "statusText": "Cluster is NOT tolerant to any failures.",
        "topology": {
            "ic-1:3306": {
                "address": "ic-1:3306",
                "mode": "R/W",
                "readReplicas": {},
                "role": "HA",
                "status": "ONLINE"
            },
            "ic-2:3306": {
                "address": "ic-2:3306",
                "mode": "R/O",
                "readReplicas": {},
                "role": "HA",
                "status": "ONLINE"
            }
        }
    },
    "groupInformationSourceMember": "mysql://icadmin@ic-1:3306"
}

How you proceed depends on whether the instance is local or remote to the instance MySQL Shell is running on, and whether the instance supports persisting configuration changes automatically, see Persisting Settings. If the instance supports persisting configuration changes automatically, you do not need to persist the settings manually and can either add more instances or continue to the next step. If the instance does not support persisting configuration changes automatically, you have to configure the instance locally. See Configuring Instances with dba.configureLocalInstance(). This is essential to ensure that instances rejoin the cluster in the event of leaving the cluster.

Once you have your cluster deployed you can configure MySQL Router to provide high availability, see Section 6.4, “MySQL Router”.

As part of using Group Replication, InnoDB Cluster creates internal recovery users which enable connections between the servers in the cluster. These users are internal to the cluster, and the user name of the generated users follows a naming scheme of mysql_innodb_cluster_server_id@%, where server_id is unique to the instance. In versions earlier than 8.0.17 the user name of the generated users followed a naming scheme of mysql_innodb_cluster_r[10_numbers]. The hostname used for the internal users depends on whether the ipAllowlist option has been configured. If ipAllowlist is not configured, it defaults to AUTOMATIC and the internal users are created using both the wildcard % character and localhost for the hostname value. When ipAllowlist has been configured, for each address in the ipAllowlist list an internal user is created. For more information, see Creating an Allowlist of Servers.

Each internal user has a randomly generated password. From version 8.0.18, AdminAPI enables you to change the generated password for internal users. See Resetting Recovery Account Passwords. The randomly generated users are given the following grants:

GRANT REPLICATION SLAVE ON *.* to internal_user;

The internal user accounts are created on the seed instance and then replicated to the other instances in the cluster. The internal users are:

In addition, the Cluster.rejoinInstance() operation can also result in a new internal user being generated when the ipAllowlist option is used to specify a hostname. For example by issuing:

Cluster.rejoinInstance({ipAllowlist: "192.168.1.1/22"});

all previously existing internal users are removed and a new internal user is created, taking into account the ipAllowlist value used.

For more information on the internal users required by Group Replication, see User Credentials For Distributed Recovery.

Instances that belong to a cluster use different ports for different types of communication. In addition to the default port at 3306, which is used for client connections over classic MySQL protocol, and the mysqlx_port, which defaults to 33060 and is used for X Protocol client connections, there is also a port for internal connections between the instances in the cluster which is not used for client connections. This port is configured by the localAddress option, which configures the group_replication_local_address system variable, and this port must be open so that the instances in the cluster can communicate with each other. For example, if your firewall is blocking this port then the instances cannot communicate with each other, and the cluster cannot function. Similarly, if your instances are using SELinux, you need to ensure that all of the required ports used by InnoDB Cluster are open so that the instances can communicate with each other. See Setting the TCP Port Context for MySQL Features and MySQL Shell Ports Reference.

When you create a cluster or add instances to a cluster, by default the localAddress port is calculated by multiplying the target instance's port value by 10 and then adding one to the result. For example, when the port of the target instance is the default value of 3306, the calculated localAddress port is 33061. You should ensure that port numbers used by your cluster instances are compatible with the way localAddress is calculated. For example, if the server instance being used to create a cluster has a port number higher than 6553, the dba.createCluster() operation fails because the calculated localAddress port number exceeds the maximum valid port which is 65535. To avoid this situation either use a lower port value on the instances you use for InnoDB Cluster, or manually assign the localAddress value, for example:

mysql-js> dba.createCluster('testCluster', {'localAddress':'icadmin@ic-1:33061'}