Have a look to [pierreozoux/confd](https://registry.hub.docker.com/u/pierreozoux/confd/) to have automatic configuration of HAproxy backed by `etcd` or `consul`.
Have a look to [indiepaas/confd](https://registry.hub.docker.com/u/indiepaas/confd/) to have automatic configuration of HAproxy backed by `etcd` or `consul`.