Docker Driver Support To Enable Privileged Mode

In order to make a NFS mount (or a mount in general) or to use docker in docker it is needed to start a container in the privileged mode.

docker run -privileged -d centos /bin/bash

The docker drive could support that feature to enable the privileged mode via meta data.

nova boot --meta "Privileged=true" --flavor m1.tiny --image centos:latest

This feature might not make much sense for a public cloud provider since it is a security risk. For that reason I propose to disable the feature by default and provide a configuration property to enable it.