Embedded Docker (HELP)

We are using docker on an appliance. The way we install images on this appliance is by building the images on a build host, exporting the images to a tgz file with the docker save command, and including that tgz file in our embedded rootfs. When the appliance boots up, it installs the tgz files using the docker load command. This works, and appears to be the normal and supported way to do this as I have found by perusing the discussions.

But, it’s got drawbacks.

  1. We end up installing a .tgz in the appliance’s rootfs that is only used to install the images. It is otherwise unused and is redundant.

  2. Since we are a secure system, the only secure storage we have to install the image is in the rootfs. But, we want to make the rootfs read only so we want the images pre-installed.

  3. loading the image during boot slows up boot.

What I really, really, want to do is pre-install /var/lib/docker into the rootfs. I have tried taking /var/lib/docker from our build host and install it on the appliance. But, the docker daemon will hang. Is there a way to get this to work? I’m not running the exact same version of docker on the build host and on the appliance. Is this the issue or is the issue more fundamental.