[help] Is it possible to do dynamic routing based on if a HTTP application is responding?

HI,

I am currently looking at the possibility of trying to implement some form of dynamic routing if an application is not responding without the need of some load balancers or reverse proxy server, and hoping for some input if this is possible.

What I want to achieve is we have a set of applications running on a web cluster in our main DC. At each of our branch sites we have a small number of servers, which I we would like to move the application from the DC to run locally at each site. Each site setup is simple, we have 3 networks – client, server and MPLS transited network. These networks reside on an ASA firewall and the clients/server default gateway is the ASA. All traffic is then routed via the MPLS to head office.

The issue is, we want to avoid changing any URLs and do not have the possibility do geo DNS records which makes this harder. Now what I was thinking was creating a 4th subnet which hosts the web application at each site with a generic IP range (which is used at each site) . we advertise this generic range into the MPLS network and update DNS to the new web server IP range.

Web server at site A <- 192.168.111.0/24 -> ASA <- MPLS router -> MPLS Cloud <- MPLS -> ASA <- 192.168.111.0/24 - > Web server at site B

This would mostly work as if the ASA interface the web servers are connect is discounted, the ASA would route traffic to the MPLS network which will know it can get to 192.168.11.0 at site B aswell. The issue is we want to be able to stop advertise 192.168.11.0/24 at a site if the web application stop responding to http gets. Looking at the ASA this does not seem possible, however it seems like ISR routers support IPSLA on HTTP gets (which can be used on a track on a static route). This seems like it might work, but would mean purchasing additional equipment.

Do people have any other suggestions?

Thanks