[libvirt] Allow custom metadata in domain configuration XML

[Zeeshan Ali (Khattak)]

Hi Eric,

On Fri, Jan 20, 2012 at 11:55 PM, Eric Blake <eblake at redhat.com> wrote:
> On 01/20/2012 01:15 PM, Zeeshan Ali (Khattak) wrote:
>> From 6895c107970ea6daf3d0e7f8be9a1a4e97b2278b Mon Sep 17 00:00:00 2001
>> From: "Zeeshan Ali (Khattak)" <zeeshanak at gnome.org>
>> Date: Fri, 20 Jan 2012 21:50:35 +0200
>> Subject: [PATCH] Allow custom metadata in domain configuration XML
>>
>> Applications can now insert custom nodes and hierarchies into domain
>> cofiguration XML. Although currently not enforced, application are
>> required to use their own namespaces on every custom node they insert.
>
> Looks like an interesting idea, as it gives applications more structure
> than what they would get by overloading the free-form <description>.

Thanks but four people contributed to this idea so I can't take much credit.

> Hmm, you didn't update docs/schemas/domaincommon.rng.

Didn't know there is one. :)

> But how do you
> write a schema that accepts a <metadata> element with arbitrary
> contents?  </me searches the web...>
>
> http://www.oasis-open.org/committees/relax-ng/tutorial.html#IDAFLZR

That might be an issue, I'll look into it.

>> @@ -11833,6 +11841,19 @@ virDomainDefFormatInternal(virDomainDefPtr def,
>>              goto cleanup;
>>      }
>>
>> +    /* Custom metadata comes at the end */
>> +    if (def->metadata) {
>> +        xmlBufferPtr xmlbuf;
>> +
>> +        xmlbuf = xmlBufferCreate();
>> +        if (xmlNodeDump(xmlbuf, def->metadata->doc, def->metadata, 2, 0) < 0) {
>
> Is this the right level of indentation if buf itself already has
> indentation (such as when <domain> is nested inside <domainsnapshot>?
> You may need to use virBufferGetIndent() and use that to alter the
> fourth argument to xmlNodeDump accordingly.

K.

> Unless anyone else objects to this XML addition, I think it is probably
> okay; but I have a couple caveats:
>
> 1. you need to add tests that prove we can parse/regenerate user XML
> (that is, qemuxml2xmltest.c needs a new test case, and I'd also like to
> see one of the snapshot xml tests covering this to ensure indentation
> was taken care of)

Will do!

> 2. we probably need an API to allow the user to change this XML on the
> fly for a running domain.

Do we? I'm not sure about that. At least we (in Boxes context) dont'
need it and I'm lazy. :)

-- 
Regards,

Zeeshan Ali (Khattak)
FSF member#5124