haproxy wrapper scripts when real servers change state ?

[Guillaume Demillecamps]

Hello all,

I was wondering if you'd have some idea on how to set up this. I host  
multiple services, internet facing. I have had multiple ISP's for  
redundancy in the past, but I always ended up with some issue. Let's  
say I have one service with an IP address from ISP #1 and one IP  
address from ISP #2. Assume my ISP #1 starts failing. DNS queries will  
still return records with the failing IP address.

Could we use haproxy to have some wrapper script, so that when  
monitoring the gateway of the ISP (or any other external IP address  
that supposedly is always up, routed always through the same ISP), if  
the service is down, DNS records are updated to stop publishing the  
defunct A record ? The DNS I'm using is PowerDNS, with postgresql  
backend, so, very easily, a record could be amended with some shell  
script.

I'm asking this because I know of some Cisco product that can provide  
that service (very expensively). But I would love to see this  
achievable with haproxy instead.

Thank you !