[libvirt] [PATCH v2 1/2] Qemu/Gluster: Add Gluster protocol as supported network disk formats.

[Paolo Bonzini]

Il 26/10/2012 11:36, Harsh Bora ha scritto:
> On 10/05/2012 05:27 PM, Paolo Bonzini wrote:
>> Il 04/10/2012 15:31, Harsh Prateek Bora ha scritto:
>>> Qemu accepts gluster protocol as supported storage backend beside
>>> others.
>>> This patch allows users to specify disks on gluster backends like this:
>>>
>>>      <disk type='network' device='disk'>
>>>        <driver name='qemu' type='raw'/>
>>>        <source protocol='gluster' name='volume/image'>
>>>          <host name='example.org' port='6000' transport='tcp'/>
>>>        </source>
>>>        <target dev='vda' bus='virtio'/>
>>>      </disk>
>>>
>>> Note: In the <host> element above, transport is an optional attribute.
>>> Valid transport values are tcp, unix or rdma. If none specified, tcp
>>> is assumed.
>>> If transport type is unix, host name specifies path to unix socket.
>>
>> I would rather add a new attribute "socket" than overload the host name.
>>   The host name for Unix sockets is really localhost.
> 
> After looking into the URI infra, I realized, it is better to have the
> new attribute name as 'query' since socket=</path/to/socket> in
> qemu-gluster commandline is nothing but a query in the whole URI
> following by a '?' character.
> 
> Since, the _virURI struct in libvirt also has a member 'query' for the
> query string in a URI, it makes sense to keep the XML attribute as
> generic as that so that it can be used by others for related purpose.

No, each query parameter should map to a separate XML attribute or element.

> Needless to say, users will have to specify sockets as
> <host name='example.org' port='6000' transport='unix'
> query='socket=/path/to/sock' />
> 
> Also, since the libvirt mandates the host element to be provided a name
> and port

Then change the schema.  In RNG it would be like this:

              <zeroOrMore>
                <element name="host">
                  <choice>
                    <group>
                      <optional>
                        <attribute name="transport">
                          <choice>
                            <value>tcp</value>
                            <value>rdma</value>
                          </choice>
                        </attribute>
                      </optional>
                      <attribute name="name">
                        <ref name="dnsName"/>
                      </attribute>
                      <attribute name="port">
                        <ref name="unsignedInt"/>
                      </attribute>
                    </group>
                    <group>
                      <attribute name="transport">
                        <value>unix</value>
                      </attribute>
                      <attribute name="socket">
                        <ref name="absFilePath"/>
                      </attribute>
                    </group>
                  </choice>
                </element>
              </zeroOrMore>


> , but the qemu-gluster commandline doesnt allow server-port for
> the unix transport, it will have to be handled differently, otherwise
> the virURIFormat will add in the server, port info into the URI.

An empty host and port will return gluster+unix:///volname?server=/path
correctly after virURIFormat.

Paolo