HAProxy doesn't support reloading the configuration, it needs to be restarted in a special way. That doesn't play well when HAProxy is managed by upstart or something like that. Most of the solutions I found were tightly coupled to upstart which I don't like. I created a script which wraps HAProxy and which in turn can be used by upstart like any other executable.
My hope is that this becomes a thing ppl like me find easily and saves them hours of research.
This wrapper accepts SIGHUB and reloads HAProxy properly. Anything that kills the wrapper also kills HAProxy. It shall not surprise you!
haproxywrapper /path/to/pid /path/to/config