Failover automatic alerts?

[Grossartig]

So with two OPNsense boxes, CARP, pfSense, XMLRPC all set up, is there a good way to have an alert sent to me when box A fails over to box B?

This is a single-WAN setup with two OPNsense boxes and CARP only on LAN (described here: https://forum.opnsense.org/index.php?topic=28315.0). I basically just want to know if box A somehow went down and box B took over. I have a gateway group defined and in a normal scenario, box B routes traffic through box A, unless box A went down and box B becomes master, then box B routes directly through WAN_DHCP.

EDIT: To answer my own question, "Monit" seems to be the answer