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

[Karel Zak]

On Fri, Aug 25, 2006 at 11:00:50PM +0100, Daniel P. Berrange wrote:
> On Fri, Aug 25, 2006 at 11:55:22PM +0200, Karel Zak 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 -
> > 
> >   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".
> 
> Well we can't break API - and there's a whole bunch of commands which
> don't start with 'dom' prefix - pause, shutdown, create, resume, vcpuinfo,
> setmem, setmaxmem, to name just a few - apart from nodeinfo & create
> essentially every command performs some kinda of operation on a domain.
> So I think needing to prefix all with 'dom' is a little overkill.

 OK. Agree.

> I agree that 'genxml' is a terrible name I suggest though - domgen is
> nicer - or as below - just allow the args to be passed to regular create
> command instead of an XML file path.

 I think the args for the create command is nice solution, but domgen
 too. We should support both. I will be very happy with something
 like:

  virsh domgen -name Foo -m 256 -hda image.dsk > /etc/xen/Foo.xml

> >  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? ;-)
> 
> A little over-engineering - if we want to let people override contents of
> an XML file - i'd just combine both into one, eg
> 
>     virsh create  -hda /path/file.img  /etc/xen/Foo.xml

 Good idea.

    Karel

-- 
 Karel Zak  <kzak at redhat.com>