[libvirt] [PATCH v3 1/2] network: Introduce network hooks

[Michal Privoznik]

On 11.02.2014 10:54, Daniel P. Berrange wrote:
> On Mon, Feb 10, 2014 at 07:52:34PM +0100, Michal Privoznik wrote:
>
>> @@ -3583,6 +3639,48 @@ validate:
>>           }
>>       }
>>
>> +    /* finally we can call the 'plugged' hook script if any */
>> +    if (virHookPresent(VIR_HOOK_DRIVER_NETWORK)) {
>> +        /* the XML construction is a bit complicated here,
>> +         * as we want to pass both domain XML and network XML */
>> +        virBuffer buf = VIR_BUFFER_INITIALIZER;
>> +        char *xml, *net_xml, *dom_xml;
>> +        int hookret;
>> +
>> +        net_xml = virNetworkDefFormat(netdef, 0);
>> +        dom_xml = virDomainDefFormat(dom, 0);
>> +
>> +        if (!net_xml || !dom_xml) {
>> +            VIR_FREE(net_xml);
>> +            VIR_FREE(dom_xml);
>> +            goto error;
>> +        }
>> +
>> +        virBufferAdd(&buf, net_xml, -1);
>> +        virBufferAdd(&buf, dom_xml, -1);
>
> This isn't very easy for applications to consume. With all the
> other things you can just pass stdin straight to your XML
> parser and process it. When you concatenate 2 XML docs this
> way it becomes much harder, since you have to split the two
> docs which means parsing them without an XML parser. Usually
> you'd want to place the 2 docs within a parent XML doc so the
> overall result is still a single wellformed XML doc.

Okay, but how should the XML look then?
<hookData>
   <network/>
   <domain/>
</hookData>

I'm basically asking about the root element name. Then, if we do this 
for plug & unplug - should we follow the same scheme for network start & 
stop? Without the <domain/>. You know, once we require hook script to 
take network xml from /hookData/network we can do that for other cases 
too, so the XPath to select the network doesn't change. Or is that an 
overkill, because the hook script can easily do:

if [ "$2" == "plugged" -o "$2" == "unplugged" ]; then
   XPATH="/hookData/network"
else
   XPATH="/network"
fi


Michal