When Docker boots a container, it will need to start the container from a Docker image, similar to how it needs to start a virtual machine from a disk image. Nova will need to pull this container from Glance. This means that Glance needs to know how to manage Docker containers. In Mitaka, Glance knows how to handle Docker containers by default. This can be confirmed by looking in the /etc/glance/glance-api.conf file and verifying that docker is listed in the container_formats list. Note that container of container_formats here does not refer to a docker container. It is related to the storage capabilities that Glance has.
Now that it has been confirmed that Glance can manage the Docker container, one must be imported into Glance and made available to boot a container instance. To do this, you use Docker to get images and then import them into Glance so they are available to Nova at spawn time for the instance. Docker needs to be installed...