Comment 5 for bug 1515463

root.tar.xz images are available for all series and all architectures and are indeed on cloud-images.ubuntu.com

I've not checked them all myself but after the CPC team told me they added them to their generated images, I did confirm (through LXD which uses them) that at least precise, trusty, vivid, wily and xenial are all available and working on x86 and armhf.