docker-workbench-proxy is a customised nginx-proxy container which is used as the built-in reserse proxy for Docker Workbench.
Docker Workbench Proxy can be run manually in a docker-workbench VM using;
docker-machine ssh <machine-name>
docker run -d --restart=always --name=docker_workbench_proxy -p 80:80 -v '/var/run/docker.sock:/tmp/docker.sock:ro' justincarter/docker-workbench-proxy