Re: [Libvir] [RFC] Add Container support to libvirt

15 Jan 2008

      Thanks again for the feedback.  I've made the following additional 
recommended changes:
* Changed filesystem tag for consistency
* Changed network spec to match most recent OpenVZ format.  The latest 
OpenVZ format I could find was here:
https://www.redhat.com/archives/libvir-list/2007-August/msg00209.html
Shuveb - does this line up with what OpenVZ is now using?
* Removed cpushare and memory tuning parameters

Updated format:
<domain type='linuxcontainer'>
   <name>Container123</name>
   <uuid>8dfd44b31e76d8d335150a2d98211ea0</uuid>
   <container>
       <filesystem type="mount">
          <source dir="/home/user/lxc_files/etc/"/>
          <target dir="/etc/"/>
       </filesystem>
       <filesystem type="mount">
          <source dir="/home/user/lxc_files/var/"/>
          <target dir="/var/"/>
       </filesystem>
       <application>/usr/sbin/container_init</application>
       <network>
           <ipaddress>192.168.1.110</ipaddress>
           <hostname>browndog</hostname>
           <gateway>192.168.1.1</gateway>
           <nameserver>192.168.1.1</nameserver>
           <netmask>255.255.255.0</netmask>
       </network>
   </container>
   <devices>
       <console tty='/dev/pts/4'/>
   </devices>
</domain>

As always, all comments and questions are welcome.

Daniel P. Berrange wrote:
...
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.
-- 

Best Regards,
Dave Leskovec
IBM Linux Technology Center
Open Virtualization