[Openstack] Glance x-image-meta-type raw vs machine

John Purrier john at openstack.org
Mon Jan 10 16:59:05 UTC 2011

Jay, this makes a lot of sense. For disk formats I would suggest: VHD, VDI, VMDK, RAW, & QCOW2. For the appliance formats: OVF, OVA, & AMI.

Conversion within Glance will need to be able to handle both disk image conversion and appliance format conversion.


-----Original Message-----
From: Jay Pipes [mailto:jaypipes at gmail.com] 
Sent: Monday, January 10, 2011 10:26 AM
To: John Purrier
Cc: Ewan Mellor; openstack at lists.launchpad.net
Subject: Re: [Openstack] Glance x-image-meta-type raw vs machine

And I think we need to come to an agreement on the terms used here...

What is a "type" of virtual image? Do we mean a *disk* image format?
Do we mean a *metadata envelope* type (OVF, AMI, etc)? Do we mean some
"type" of system image or image part (kernel, ramdisk, etc)?

What Glance is serving/registering is really called a *virtual
appliance*, as described in this article:


Change the Image model to have these following fields, instead of the
existing "type" column:

disk_format -- choice between ('VHD', 'VDI', 'VMDK')
appliance_file_format -- choice between ('AMI','OVF')


On Mon, Jan 10, 2011 at 11:11 AM, John Purrier <john at openstack.org> wrote:
> My 2 cents... We need to define a transport-neutral specification that allows us to encapsulate and copy/move a variety of virtual image formats, this should be based on OVF. The envelope can contain both the actual image as well as any required meta-data.
> The image elements specified are very AMI specific, we should generalize to be able to indicate the type of virtual image (i.e. AMI, VHD, etc.). A test for POC can be a service that takes the data in the OVF or what is stored in Glance to convert between formats. If we do this correctly all of the required data will be available at the correct point in the flow.
> Don't know if this is directly applicable to the discussion point below, but it is important that we get the fundamental design/architecture concepts in place moving forward.
> John
> -----Original Message-----
> From: openstack-bounces+john=openstack.org at lists.launchpad.net [mailto:openstack-bounces+john=openstack.org at lists.launchpad.net] On Behalf Of Jay Pipes
> Sent: Monday, January 10, 2011 9:44 AM
> To: Ewan Mellor
> Cc: openstack at lists.launchpad.net
> Subject: Re: [Openstack] Glance x-image-meta-type raw vs machine
> On Sat, Jan 1, 2011 at 7:30 PM, Ewan Mellor <Ewan.Mellor at eu.citrix.com> wrote:
>> What is the intended semantics of the Glance x-image-meta-type header values
>> “raw” vs “machine”?
> When we pulled the Image model from Nova into Glance, there was a
> field "image_type" that was limited to the strings "raw", "machine",
> "kernel", and "ramdisk".
> I'm open to changing this or using something like a "format" field
> (AMI vs OVF, etc..)
> Thoughts?
> -jay
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