6.4.6 Working with a Cluster's Routers

You can bootstrap multiple instances of MySQL Router against InnoDB Cluster or InnoDB ReplicaSet. From version 8.0.19, to show a list of all registered MySQL Router instances, issue:

Cluster.listRouters()

The result provides information about each registered MySQL Router instance, such as its name in the metadata, the hostname, ports, and so on. For example, issue:

mysql-js> Cluster.listRouters()
{
    "clusterName": "example",
    "routers": {
        "ic-1:3306": {
            "hostname": "ic-1:3306",
            "lastCheckIn": "2020-01-16 11:43:45",
            "roPort": 6447,
            "roXPort": 64470,
            "rwPort": 6446,
            "rwXPort": 64460,
            "version": "8.0.19"
        }
    }
}

The returned information shows:

• The name of the MySQL Router instance.

• Last check-in timestamp, which is generated by a periodic ping from the MySQL Router stored in the metadata

• Hostname where the MySQL Router instance is running

• Read-Only and Read-Write ports which the MySQL Router publishes for classic MySQL protocol connections

• Read-Only and Read-Write ports which the MySQL Router publishes for X Protocol connections

• Version of this MySQL Router instance. The support for returning version was added in 8.0.19. If this operation is run against an earlier version of MySQL Router, the version field is null.

Additionally, the Cluster.listRouters() operation can show a list of instances that do not support the metadata version supported by MySQL Shell. Use the onlyUpgradeRequired option, for example by issuing Cluster.listRouters({'onlyUpgradeRequired':'true'}). The returned list shows only the MySQL Router instances registered with the Cluster which require an upgrade of their metadata. See Section 6.5, “Upgrade Metadata Schema”.

MySQL Router instances are not automatically removed from the metadata, so for example as you bootstrap more instances the InnoDB Cluster metadata contains a growing number of references to instances. To remove a registered MySQL Router instance from a cluster's metadata, use the Cluster.removeRouterMetadata(router) operation, added in version 8.0.19. Use the Cluster.listRouters() operation to get the name of the MySQL Router instance you want to remove, and pass it in as router. For example suppose your MySQL Router instances registered with a cluster were:

mysql-js> Cluster.listRouters(){

    "clusterName": "testCluster",
    "routers": {
        "myRouter1": {
            "hostname": "example1.com",
            "lastCheckIn": null,
            "routerId": "1",
            "roPort": "6447",
            "rwPort": "6446"
            "version": null
        },
        "myRouter2": {
            "hostname": "example2.com",
            "lastCheckIn": "2019-11-27 16:25:00",
            "routerId": "3",
            "roPort": "6447",
            "rwPort": "6446"
            "version": "8.0.19"
        }
    }
}

Based on the fact that the instance named “myRouter1” has null for “lastCheckIn” and “version”, we decide to remove this old instance from the metadata by issuing:

mysql-js> cluster.removeRouterMetadata('myRouter1')

The MySQL Router instance specified is unregistered from the cluster by removing it from the InnoDB Cluster metadata.