(dotCloud employee here) We are very much aware of HAProxy, love it, and would have been very happy to use it. For the majority of use cases we would probably

(dotCloud employee here) We are very much aware of HAProxy, love it, and would have been very happy to use it. For the majority of use cases we would probably recommend it over Hipache, simply because it's more proven. However, our particular use case involves a) a very large number of vhosts, and b) a highly dynamic topology where backends are added and removed very frequently. In this setup, instrumenting a cluster of HAProxy (or nginx) boxes basically means re-generating and reloading multi-megabyte configuration files across dozens of machines, several times per second. It's what we did before Hipache, and it was painful. Compared to that, implementing active health checks was a small price to pay.