[Libvir] [RFC] Add Container support to libvirt

[Daniel P. Berrange]

On Tue, Jan 15, 2008 at 12:26:43AM -0800, Dave Leskovec wrote:
> Greetings,
> 
> Following up on the XML format for the Linux Container support I 
> proposed...  I've made the following recommended changes:
> * Changed mount tags
> * Changed nameserver tag to be consistent with gateway
> * Moved cpushare and memory tags outside container tag
> 
> This is the updated format:
> <domain type='linuxcontainer'>
>   <name>Container123</name>
>   <uuid>8dfd44b31e76d8d335150a2d98211ea0</uuid>
>   <container>
>       <filesystem>
>           <mount>
>               <source dir="/home/user/lxc_files/etc/"/>
>               <target dir="/etc/"/>
>           </mount>
>           <mount>
>               <source dir="/home/user/lxc_files/var/"/>
>               <target dir="/var/"/>
>           </mount>
>       </filesystem>

Comparing this to the Linux-VServer XML that Daniel posted, you're both
pretty much representing the same concepts so we need to make a decision
about which format to use for  filesystem mounts.

OpenVZ also provides a /domain/container/filesystem tag, though it
uses a concept of filesystem templates auto-cloned per container
rather than explicit mounts. I think I'd like to see

       <filesystem type="mount">
               <source dir="/home/user/lxc_files/etc/"/>
               <target dir="/etc/"/>
       </filesystem>

For the existing OpenVZ XML, we can augment their <filesystem> tag with
an attribute  type="template".

>       <application>/usr/sbin/container_init</application>
>       <network hostname='browndog'>
>           <ip address="192.168.1.110" netmask="255.255.255.0"/>
>               <gateway address="192.168.1.1"/>
>               <nameserver address="192.168.1.1"/nameserver>
>           </ip>
>       </network>

Again this is pretty similar to needs of VServer / OpenVZ. In the existing
OpenVZ XML, the gateway and nameserver tags are immediately within the
<network> tag, rather than nested inside the <ip> tag. Aside from that it
looks to be a consistent set of information.

>   </container>
>   <cpushare>40</cpushare>

As Daniel points out, we've thus far explicitly excluded tuning info from
the XML. Not that I have any suggestion on where else to put it at this
time. This is a minor thing though, easily implemented once we come to a
decision.

>   <memory>65536</memory>
>   <devices>
>       <console tty='/dev/pts/4'/>
>   </devices>
> </domain>
> 
> Does this look ok now?  All comments and questions are welcome.

Pretty close.

Dan.
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