Today I loaded up one of my haproxy instances on amazon ec2 and I decided it was a good idea to take a quick peak at the haproxy.log to be sure it booted it correctly etc… I saw a ton of entries (several per second) being added to the log that looked something like this:
Jul 21 09:44:19 localhost haproxy: 127.0.0.1:55422 [21/Jul/2011:09:44:19.707] webserver webserver/
-1/-1/-1/-1/0 400 0 - - SC-- 1998/0/0/0/0 0/0 " "
I ran a quick check on the config file to be sure it was all good and sure enough the address for the webserver returned the error “Invalid server name: ‘webserver.example.com'”. Obviously that server no longer reponds, in this case it was a server that we no longer were using and my config on this machine was out of date, I updated the config, (re-ran the check) and restarted. Good to go.