[openstack-dev] RFC: Recording/providing ISO image headers in glance

Mac Innes, Kiall kiall at hp.com
Wed Jan 30 11:28:56 UTC 2013

Just throwing this out there, I don't necessarily have an opinion either

What about using the HTTP Range header to ask for the first X bytes of
the image? This certainly isn't as efficient for the client as a
dedicated API endpoint, but would not require explicit support for
individual formats to be implemented.

(I'm assuming there is some sort of fixed maximum length for the ISO header)


On 30/01/13 10:58, Daniel P. Berrange wrote:
> Some apps have a need to be able to obtain ISO filesystem headers from
> images stored in glance. Now obviously they can just download the image
> (or part of it) and run 'isoinfo' on it, but this is really horrifically
> inefficient/wasteful of bandwidth. It would be desirable for glance to
> have explicit support for this in some way.
> I've written a short wiki page describing one approach, which is to
> make glance extract the data upon upload of an ISO and store it in
> some well-defined metadata properties against the image.
>     http://wiki.openstack.org/GlanceISOHeaders
>     https://blueprints.launchpad.net/glance/+spec/iso-image-metadata
> A completely different approach we be to ignore metadata properties
> and add an explicit API to glance which would extract it on-demand,
> but I feel this is a needlessly large amount of work & less convenient
> and flexible than simply using existing metadata properties.
> Regards,
> Daniel

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