At the moment cloud-init accepts it's parameter from the attached (or not) ISO on the source VM, this ISO instructs cloud-init to fill the disk with random junk at a certain % of free space. 

If we don't mind we can keep things as is but the same cloud-init parameters can be handled via Python (dynamic) rather than a static fill 50% ISO. 

This ties in to other tasks on this list, for example if we opt to use pre-configured VMs which we just clone we don't need to invest time on this and keep the current ISO.