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

[Daniel P. Berrange]

On Fri, Aug 25, 2006 at 02:57:25PM -0400, Daniel Veillard wrote:
> 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 -
> > 
> > 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 :-)
> 
>   Okay, but this is dependant on the virtualization used, e.g. test and
> xen XML will provide different output. But with the environment variable
> patch this can be hidden from the command line.

Yeah, if you don't set the env var, I'd expect the --connect parameter to
be used in any case so we can easily generate appropriate XML

>   Either way is fine, actually the code is gonna be 90% the same, and both
> ways sounds useful in slightly different contexts, why not both ?

Sure :-)

Dan.
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