On Thu, Sep 25, 2014 at 09:19:03AM -0500, Matt Riedemann wrote:
> On 9/25/2014 8:26 AM, Pasquale Porreca wrote:
> >The problem to use a different tag than UUID is that it won't be
> >possible (for what I know) to include this tag in the Bootstrap Protocol
> >messages exchanged during the pre-boot phase.
> >
> >Our original idea was to use the Client-identifier (option 61) or Vendor
> >class identifier (option 60) of the dhcp request to achieve our target,
> >but these fields cannot be controlled in libvirt template and so they
> >cannot be set in OpenStack either. Instead the UUID is set it the
> >libvirt template by OpenStack and it is included in the messages
> >exchanged in the pre-boot phase (option 97) by the instance trying to
> >boot from network.
> >
> >Reference:
> >http://www.iana.org/assignments/bootp-dhcp-parameters/bootp-dhcp-parameters.xhtml


> If it's a matter of getting the instance tag information down to the libvirt
> driver on boot that shouldn't be a problem, there are others asking for
> similar things, i.e. I want to tag my instances at create time and store
> that tag metadata in some namespace in the libvirt domain xml so I can have
> an application outside of openstack consuming those domain xml's and reading
> that custom namespace information.

Perhaps I'm misunderstanding something, but isn't the DHCP client that
needs to send the tag running in the guest OS ? Libvirt is involved wrt
UUID, because UUID is populated in the guest's virtual BIOS and then
extracted by the guest OS and from there used by the DHCP client. If
we're talking about making a different tag/identifier available for
the DHCP client, then this is probably not going to involve libvirt
unless it also gets pushed up via the virtual BIOS. IOW, couldn't you
just pass whatever tag is needed to the guest OS via the configdrive
or metadata service.

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