Is there a way to force heartbeat to add new ip addresses to the system without a full restart?

Solution 1:

The problem was that I didn't wait long enough after executing "heartbeat -r" (the command that is executed in the init.d script when you run "service heartbeat reload".) After a few minutes, the IP showed up on the interface as expected.

Solution 2:

You don't need to reload Heartbeat at all. Simply add the new IPaddr resource to your haresources file, something like this

IPaddr::xx.xx.xx.xx

and then start it

/etc/ha.d/resource.d/IPaddr xx.xx.xx.xx start

Of course, you should make sure to issue the IPaddr start on the active node. You should now be able to send and receive traffic on the just added IP address.