Not to hijack the thread, just wondering anyone has experience with zero-downtime deployment of multi-container app with cross-container communication?
Vagrant is a great technology, but I recommend taking a look at Docker compose (https://docs.docker.com/compose/) previously known as FIG. One of the great advantages of compose is that combine it with Swarm (https://github.com/docker/swarm) and you have a very robust distributed deployment system. Docker-machine is the direct competitor to vagrant, but to be honest, I don't use it. I spin up my docker containers via some build in service API's we already built for proprietary reasons.
If you want to get really robust, you can also look at Kubernetes (and their zero-downtime deployment) and Mesos. These both add a huge amount of complexity t the deployment, but also grant a robust distributed system for managing downtime and deployment. Redhat also has Openshift.
What I'm looking for is a robust and systematic zero-downtime approach to update some of the containers (say in a loadBalancer → web servers → db architecture).