For scenarios where I felt etcd/gconf/consul is overkill I wrote goconfd (https://github.com/niko/goconfd). Features:

* reads config from a json file * GET requests with deep links into the json tree * POST request with template as body and deep links (using the go template engine, too) * long polling (response has to be triggered explicitly by a PUT request)

I also made a simple docker container running HAProxy - configured by goconfd - to orchestrate docker containers.