[openstack-dev] [nova] Flavor extra-spec and image metadata documentation

Daniel P. Berrange berrange at redhat.com
Wed Feb 11 11:15:45 UTC 2015


On Wed, Feb 11, 2015 at 12:03:58PM +0100, Pasquale Porreca wrote:
> Thank you for all answers.
> I know that meta data tags are "free" to use with any key/value, still
> there are some specific values that triggers pieces of code in nova (or
> maybe even in other components). In particular I am working on one of
> these key/value, in my case it should enable the
> 
> <bios rebootTimeout=value/>
> 
> parameter in libvirt. Anyway even if my code is merged, no one will know
> about it (except myself and the reviewers) if it is not documented
> somewhere. A DocImpact flag was added to the commit message, but I still
> don't know how to proper document it. I may create/update existing wiki
> pages, but I would have preferred an official documentation: I was not
> able to find the wiki page proposed by Daniel Berrange, even if I had
> been searching exactly to something similar :(
> It is very good that there is a work to objectify image meta, anyway is
> there any recommendation  how to document it in the meanwhile?

For people submitting patches to nova the expectation is simply that they
add DocImpact and have a commit message that describes the usage of the
new property. The docs team work from this data. There's no current formal
docs that I'd expect you to be editing/updating.

> I would also know if there is any naming convention for image meta and
> flavor extra-spec keys: in my case I used hw_reboot_timeoutand
> hw:reboot_timeout respectively, but it is more a bios than hardware
> feature and they are handled in nova/virt/libvirt/driver.py rather than
> nova/virt/hardware.py so maybe the name choice was not so good.

In terms of image metadata, broadly speaking, we're aiming to standardize
on 3 name prefixes in Nova

 'hw' - stuff that affects guest hardware configuration (this includes
        the BIOS settings, since that's hardware firmware)
 'os' - stuff that affects the guest operating system setup
 'img' - stuff Nova uses related to managing images

So, your choice of 'hw_reboot_timeout' for image and 'hw:reboot_timeout'
for the flavour  is correct.

Regards,
Daniel
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