In this document it says that:
Overlay networking for Docker Engine swarm mode comes secure out of the box. You can also encrypt data exchanged between containers on different nodes on the overlay network. To enable encryption, when you create an overlay network pass the --opt encrypted flag:
> $ docker network create --opt encrypted --driver overlay my-multi-host-network
So if all the containers are running on the my-multi-host-network
is all the traffic between the containers encrypted automatically? In other words it's as if all the containers were running SSL and if rest is used to communicate from container A to container B, the REST request (Or requests via any other communication protocol - AMQP, etc) is encrypted?