How does Fabio handle being a single point of failure?
This might be naiveté on my part, but I would assume you run multiple Fabio instances and treat it like you would any other LB.
Do you mean something else by your question?
Yes I meant something different. Generally with a load balancer the load balancer hosts that VIP(s) that your public facing DNS A records resolve to. In order to avoid a single point of failure you employ things like keepalived or ECMP/BGP etc.
The general setup seems to be that you have a public facing LB which just forwards all incoming traffic to any available fabio instance which handles the dynamic routing. fabio does not solve the public VIP problem for you.
Disclaimer: I'm the author.
You can run Fabio alongside the Consul agent on each node in your cluster and point all your apps to localhost:9999. That way you don't have to manage a central cluster of Fabio instances and if a node dies you just lose the Fabio instance on that host, which was only being used by that host.