how to convert manual vm to libvirtd management

how to convert manual vm to libvirtd management

[Riccardo Veraldi]

Hello,
I have always created my VM under kvm manually starting them from a .sh 
script:

for example machine called  abbone


# abbone.sh
screen qemu-kvm -nographic -hda ./abbone.img -m 512 -net 
nic,model=e1000,macaddr=00:16:3e:05:00:07 -net tap -name abbone -vnc :0


I use screen so that I am hook to the serial console and it is so easy 
to manager machien via serial console.

But now I havea problem. I vould like to use virsh to manager my virtual 
machines.

now I installed all my VM MANUALLY vithout using virt-install so I do 
not have the proper virtual machine
XML descriptor files in /etc/libvirt/qemu

without a XML description is not possible to start, shutdown, destroy 
virtual machines via virsh or virt-manager tool.

so How can I create an XML file with all the options of the above command ?

actually with the above command a proper tapN interface is created upon 
VM startup via /etc/qemu-ifup script

#!/bin/sh
set -x

switch=sw1

if [ -n "$1" ];then
        /usr/sbin/tunctl -t $1
        /sbin/ip link set $1 up
        sleep 1
        /usr/sbin/brctl addif $switch $1
        exit 0
else
        echo "Error: no interface specified"
        exit 1
fi


thanks


Rick

Re: how to convert manual vm to libvirtd management

[Daniel P. Berrange]

On Thu, Apr 09, 2009 at 07:02:02PM +0200, Riccardo Veraldi wrote:
> Hello,
> I have always created my VM under kvm manually starting them from a .sh 
> script:
> 
> for example machine called  abbone
> 
> 
> # abbone.sh
> screen qemu-kvm -nographic -hda ./abbone.img -m 512 -net 
> nic,model=e1000,macaddr=00:16:3e:05:00:07 -net tap -name abbone -vnc :0
> 
> 
> I use screen so that I am hook to the serial console and it is so easy 
> to manager machien via serial console.
> 
> But now I havea problem. I vould like to use virsh to manager my virtual 
> machines.
> 
> now I installed all my VM MANUALLY vithout using virt-install so I do 
> not have the proper virtual machine
> XML descriptor files in /etc/libvirt/qemu
> 
> without a XML description is not possible to start, shutdown, destroy 
> virtual machines via virsh or virt-manager tool.
> 
> so How can I create an XML file with all the options of the above command ?

There is a referenece for possible XML options here:

  http://libvirt.org/formatdomain.html

And some specific XML examples for QEMU:

  http://libvirt.org/drvqemu.html

> 
> actually with the above command a proper tapN interface is created upon 
> VM startup via /etc/qemu-ifup script

When using libvirt, there's no need for a ifup script, since libvirt
will create the TAP device and add it to the bridge for you.

There is a introduction to networking with libvirt here:

http://wiki.libvirt.org/page/Networking

To help you get started, to replicate your example config here:

 qemu-kvm -nographic -hda ./abbone.img -m 512 -net
  nic,model=e1000,macaddr=00:16:3e:05:00:07 -net tap -name abbone -vnc :0

You would want to create an XML doc that looks like this:

   <domain type='kvm'>
     <name>abbone</name>
     <memory>524288</memory>
     <devices>
        <emulator>/usr/bin/qemu-kvm</emulator>
        <disk type='file' device='disk'>
           <source file='/path/to/abbone.img'/>
           <target dev='hda' bus='ide'/>
        </disk>
        <interface type='bridge'>
           <source bridge='br0'/>
           <mac address='00:16:3e:05:00:07'/>
           <model type='e1000'/>
        </interface>
     </devices>
  </domain>


DOn't forget to change 'br0' to whatever bridge you are using, and
set the correct path to your abbone.img disk image

One thing that's confusing is that you have set '-nographic' and '-vnc'
which doesn't make sense. Either you want graphics or you dont !

If you want VNC graphics, then in the <devices> section of the XML
also add

    <graphics type='vnc' port='5900'/>

Then load the config into libvirt using

      virsh define /path/to/config.xml

And you can start it with

      virsh start


If you have more libvirt questions, you might wish to ask on the libvirt
mailing list

  http://www.redhat.com/mailman/listinfo/libvir-list

Regards,
Daniel
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