MySQL Router is part of InnoDB cluster, and is lightweight middleware that provides transparent routing between your application and MySQL server instances which make up an InnoDB cluster. It can be used for a wide variety of use cases, such as providing high availability and scalability by effectively routing database traffic to appropriate back-end MySQL Servers. The pluggable architecture also enables developers to extend MySQL Router for custom use cases.
For additional details about InnoDB cluster, see InnoDB Cluster.
For client applications to handle failover, they need to be aware of the InnoDB cluster's topology and know the role of each MySQL instance - whether it is primary or secondary. While it is possible for applications to implement that logic, MySQL Router provides this functionality for you. MySQL Router includes the InnoDB cluster metadata cache plugin, which enables MySQL Router to automatically configure itself based on the cluster's topology. This process is referred to as bootstrapping.
When boostrapped against an InnoDB cluster, MySQL Router acts as a proxy to the multiple MySQL instances which make up the cluster. MySQL Router maps application client requests to one of the instances in the cluster. Different ports are provided for different purposes, such as read-write or read-only sessions, using either MySQL protocol or X Protocol. If the cluster changes, for example due to a fail over, MySQL Router automatically handles changes to the roles of servers. Client applications continue to use the same MySQL Router port, while the destination server instance in the InnoDB cluster might have changed. All of this leads to a highly available MySQL database which is easy to configure.
The recommended deployment model for MySQL Router is bootstrapped against an InnoDB cluster, with Router running on the same host as the application.
Using a bootstrapped MySQL Router against an InnoDB cluster is the only recommended way of configuring Group Replication and MySQL Router.
The steps for deploying Router with an InnoDB cluster after the cluster is configured are:
Install MySQL Router.
For details, see the Installation section.
Bootstrap for an InnoDB cluster, and test.
Router can be automatically configured by calling it with
--bootstrap. During bootstrap, Router connects to the cluster, fetches its metadata, and configures itself for use. For details, see Chapter 3, Deploying MySQL Router.
Set up Router for automatic startup.
To make Router automatically start when the host reboots, you need to configure your system to start Router. This process is similar to how the MySQL server is configured to start automatically. For additional details, see Section 5.1, “Starting MySQL Router”.
For example, after creating a MySQL InnoDB cluster, you might configure Router using:
shell> mysqlrouter --bootstrap localhost:3310 --directory /opt/myrouter --user snoopy
This example bootstraps MySQL Router to an existing InnoDB cluster where:
localhost:3310is the PRIMARY with a metadata server
Creates a self-contained installation with all generated directories and files at
Only the host's system user named
snoopywill have access to
Files and directories are generated under
log/, and a fully functional MySQL Router configuration file named
related configuration options for information to modify how the
bootstrap process is configured. For example, passing in
Unix domain socket connections instead of the TCP/IP connections
which are enabled by default.
InnoDB clusters can run in a single-primary mode where one
server instance is writeable, or a multi-primary mode where
multiple servers are writeable. When bootstrapping, the ports and
sockets configured by MySQL Router are affected by the mode which the
cluster is running in. You can check the mode which a cluster is
running in by
MySQL server configuration option.
This document refers to default bootstrapping behavior. Other MySQL Router configuration options might affect this behavior, and generated configuration values can be modified after bootstrapping.
ON(the default): Both Read-Write (primary) and Read-Only (secondary) ports are configured.
OFF: Only Read-Write (primary) ports are configured.
all connections to ports 6446 and 64460 go to the single primary,
and all connections to ports 6447 and 64470 go to the secondaries
using the round-robin mode schedule.
shell> mysqlrouter --bootstrap localhost:3310 Classic MySQL protocol connections to cluster 'myCluster': - Read/Write Connections: localhost:6446 - Read/Only Connections: localhost:6447 X protocol connections to cluster 'myCluster': - Read/Write Connections: localhost:64460 - Read/Only Connections: localhost:64470
all connections to ports 6446 and 64460 go to the primaries using
the round-robin mode schedule.
shell> mysqlrouter --bootstrap localhost:3310 Classic MySQL protocol connections to cluster 'myCluster': - Read/Write Connections: localhost:6446 X protocol connections to cluster 'myCluster': - Read/Write Connections: localhost:64460