Proposal: Disk Images

[fw2568]

Disk Image proposal

Eryph should know several ways to provide image drives.

Image Sources

Currently the following sources should be implemented:

• local image data storage
  A file path or network path under which image files are stored.
• Eryph-Hub Download
  Download images from eryph-hub and cache them in local image store

Image reference in configuration

Images should be referenced by a organization, identifier and a version.

organization
Name of the image owner organization.

id
A string with the image unique name

version
A string with the image version. Each source may have a different version scheme.

A image could be specified on VM and on disk level. On disk level there is also an optional name string value to reference a disk from the image by name.

Image reference on Hypervisor

It will be necessary to download images to a path accessable by each hypervisor.
So there has to be a shared storage where all hypervisor could reference the image path. A downloaded image disks has to be readonly until all referencing VMs have been destroyed.

This reference should be tracked by the disks in VMs and image and their parent/child relationship.
Therefore the state store and inventory process will have to be extended to keep track of all disks (where they are stored, parents, childs and if they are attached to a machine or image.

AB#603