Quickly Build a MySQL InnoDB Cluster with Router for High Availability

Deploy Multiple MySQL Instances

Using the MySQL Shell client, start the shell and create sandbox instances on ports 3310, 3320, and 3330, each with the password 111111:

$ mysqlsh

mysql-js> dba.deployLocalInstance(3310)

mysql-js> dba.deployLocalInstance(3320)

mysql-js> dba.deployLocalInstance(3330)

Initialize InnoDB Cluster

Connect to the first instance and create a cluster named mycluster:

mysql-js> \c root@localhost:3310

mysql-js> cluster = dba.createCluster('mycluster')

Add the remaining instances to the cluster:

mysql-js> cluster.addInstance('root@localhost:3320')

mysql-js> cluster.addInstance('root@localhost:3330')

View Cluster Status

Run cluster.status() to see the JSON status output, confirming all three nodes are online and the primary (HA) role is on 3310.

{
    "clusterName": "mycluster",
    "defaultReplicaSet": {
        "status": "Cluster tolerant to up to ONE failure.",
        "topology": {
            "localhost:3310": {"status": "ONLINE","role": "HA","mode": "R/W"},
            "localhost:3320": {"status": "ONLINE","role": "HA","mode": "R/O"},
            "localhost:3330": {"status": "ONLINE","role": "HA","mode": "R/O"}
        }
    }
}

Deploy MySQL Router

Bootstrap the router against the primary instance: sudo mysqlrouter --bootstrap localhost:3310 Provide the administrative MASTER key (the same identifier used when creating the cluster) and note the generated connection endpoints: read/write on localhost:6446, read‑only on localhost:6447.

Start MySQL Router

# mysqlrouter &

Connect Through the Router

From a regular user, connect to the router’s read/write endpoint using MySQL Shell: mysqlsh --uri root@localhost:6446 Switch to SQL mode and verify the underlying instance port:

\sql
SELECT @@port;

The query returns 3310, confirming the router forwards traffic to the primary.

Failure Simulation

Kill the primary instance to test automatic failover: mysql-js> dba.killLocalInstance(3310) Subsequent queries through the router reconnect to the surviving instance (e.g., 3330), demonstrating seamless failover.

Conclusion

The new MySQL tools dramatically simplify building a high‑availability InnoDB cluster, but this preview method should not be used in production environments.