If you use MaxScale to route queries from various servers to some MariaDB server(s), when viewing the processlist on the MariaDB server, you will see MaxScale’s host for any “host” information related to that connection or its queries.

When tracking down problematic queries, it can be helpful to know what originating host of that query.

MaxScale’s proxy protocol to the rescue.

The proxy protocol was introduced in MaxScale 2.2 and MariaDB 10.3.

To enable it, it is quite simple (essentially just 2 changes).

1. In MariaDB, you need to set the variable proxy_protocol_networks in your my.cnf file (you can specify comma-separated IP addresses and/or subnetworks, as well as localhost and ::1):

proxy-protocol-networks=::1, 192.168.0.0/16, localhost

This one, which I will use as-is, is the example from the …