docker-compose 1.11.0 will be released soon with support for secrets, probably using the same system.
Exactly. The new version of compose supports defining docker secrets inside of the compose file.
But the question is whether secrets can be used outside swarm. It doesn't look so at first glance.
secrets only work with Swarm services. New compose (1.11) uses a new format version ( v3.1) that allows you to add secrets for services and deploy using docker client ( no need for docker-compose). I don't think there's any plans atm to support secrets for non-swarm containers :(