The Docker Flow Proxy (http://proxy.dockerflow.com/) project exposes statistics that should be reserved for internal use only. Therefore, it needs to be protected with a username and password. Before Docker v1.13, situations like that one would be handled by allowing users to specify username and password through environment variables. Docker Flow Proxy is no exception and, indeed, has the environment variables (http://proxy.dockerflow.com/config/#environment-variables) STATS_USER and STATS_PASS.
The command that would create the service with custom username and password would be as follows:
docker network create --driver overlay proxy
docker service create --name proxy \
-p 80:80 \
-p 443:443 \
-p 8080:8080 \
-e STATS_USER=my-user \
-e STATS_PASS=my-pass \
--network proxy \
-e MODE=swarm \
vfarcic/docker-flow-proxy
While that would protect the statistics...