I ran across a similar thing a few months ago named docker-gen[1]. It listens to the docker event stream in the same way Registrator does, but instead of talking to an external service it regenerates a config file from a template and then optionally runs a command. The canonical example is regenerating a host-wide nginx proxy config when containers start and die, and then restarting nginx.
Just goes to show how versatile docker can be by exposing that event stream to arbitrary processes.
Just goes to show how versatile docker can be by exposing that event stream to arbitrary processes.
[1]: https://github.com/jwilder/docker-gen