Any problems with having an active/active HAProxy setup with Keepalived

Apologies if this has been asked before, but I can't seem to find much on it.

We're going to be using HAProxy to load balance our MariaDB Galera Cluster. All the articles/tutorials I have seen on this use Keepalived (or something similar) for an active/passive HAProxy setup.

Is there any good reason why you shouldn't have an active/active setup?

Each HAProxy node can have a fixed IP and both have a floating IP. Under normal conditions requests are shared between the two HAProxy nodes, if one goes down, the other takes it's floating IP and handles requests under both IPs. When the other comes back up it takes its floating IP and share of load back again.

I'd appreciate your opinions on this.

Luke

Solution 1:

The important considerations not to have an active/active setup with two virtual IP addresses for the same resource is

• how do you distribute requests over the two virtual IP's
• how do you deal with sticky sessions, affinity, persistence and such, i.e. what happens when subsequent requests start off going to virtual IP1 and then go to virtual IP2 and do you need those to go the same back-end server.
• what happens when the virtual IP-addresses fails over to the other host?