[Libvir] RFC: A more convenient 'virsh create' command

Karel Zak kzak at redhat.com
Fri Aug 25 21:55:22 UTC 2006

On Fri, Aug 25, 2006 at 05:46:28PM +0100, Daniel P. Berrange wrote:
> The current implementation of 'virsh create' takes an XML file as its only
> parameter & creates a domain from this. This is great if you have a suitable
> XML file already, but if you are just trying to automate some simple tasks
> from the shell then the need to use XML is a little cumbersome. Thus I was
> thinking perhaps we could have an alternate way to define a new VM (keep
> the current XML based way too of course)
> QEMU for example makes it very easy to launch a new VM:
>    qemu -m 256 -hda /path/to/image.dsk -hdc /path/to/boot.iso 
> Taking inspiration from this syntax we could allow:
>    virsh start -m 256 -hda /path/to/image.dsk -hdc /path/to/boot.iso -name Foo
> Internally, the 'start' command would simply transform these command
> line args into the neccessary libvirt XML and then call the normal
> create functions.
> Another way would be have a 'genxml' command, which accepted these list
> of devices / config properties & then printed out appropriate XMl. This
> could be piped to the regular 'virsh create' command
>   virsh genxml -m 256 -hda /path/to/image.dsk -hdc /path/to/boot.iso \
>    -name Foo  | virsh create -

  What use better command name instead "genxml"? For example "domgen".
  (we have dominfo, domstate, ...). 

  Same odd commad name is "dumpxml"...  XML of what? It should be
  renamed to "domdump".

> This isn't so critical for Xen, because people are already used to writing
> config files before creating the domain, but when we get a QEMU backend
> i think such a convenient method for defining new VMs will be neccessary
> to encourage users to use virsh instead of manually calling 'qemu'. Even
> for Xen users it would make shell script easier though :-)

 I can imagine more commands like:

     virsh> bufread /etc/xen/Foo.xml
     virsh> bufedit Foo -hdc /path/file.img 
     virsh> create --frombuf Foo

 I think it could be nice for playful admins and developers. Or is
 over engineering? ;-)


 Karel Zak  <kzak at redhat.com>

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