[Ovirt-devel] Some networking and provisioning questions

[Daniel P. Berrange]

On Mon, Mar 16, 2009 at 01:46:16PM -0700, David Lutterkort wrote:
> On Mon, 2009-03-16 at 20:15 +0000, Daniel P. Berrange wrote:
> > > I'm inclined to go with solution 1, but I'm willing to be convinced
> > > otherwise.
> > 
> > Out of those options I agree option 1 is most desirable. Either let it
> > boot the ISO image, or do a direct kernel+initrd boot of the selected
> > OS. 
> 
> I think offering a kernel+initrd boot for VM's solves this nicely -
> ultimately, that's what PXE is used for almost always.
> 
> > I would add one further option - in addition - not instead of this.
> > Namely, ability to clone a pre-existing OS template. eg a hosting
> > provider may have done generic installs of Fedora, RHEL, Windows, etc.
> 
> I would be _very_ careful with this option; for OS's where you can
> install cleanly from metadata (e.g. kernel,intird and kickstart) that's
> much preferable to provisioning from an image. In the image case, you
> have to modify various bits of the image that persist information about
> the hardware, e.g. /etc/udev/rules.d/70-persistent-net.rules. It is also
> much easier to keep a small set of yum repos updated rather than needing
> to respin images every time there's a critical security fix.

I was basically using 'template' to mean the situation where a end users
new VM is provisioned on their behalf from some "canned" definition. Whether
that means a fresh unattended install from kickstart file, or cloning a
disk image from a previous kickstart'd master, its more or less the same
thing. The ISP defines the kickstart, and the first thing the user sees
is the running, installed VM, with no 'installer' step they have to worry
about.

> > Provisioning a new VM would just clone this template, and boot it and
> > now the end-user can log straight in an customize. No 'installation'
> > step as far as the end user is concerned.
> 
> That's strictly a UI issue - you can present both install from image and
> install from kickstart in the same way. Whether the additional
> capabilities of a kickstart install are exposed to the user or not is
> similarly a UI question.

Ah well this depends what you mean when saying 'install'. It can mean

 - The user / owner of the VM boots their VM into the installer
   and interacts with it
 - The ISP admin provisions a brand new VM using a scripted installer
   (eg kickstart)

I was refering to the former. The latter is really just another form of
templating. Indeed in the latter case, then it would be reasonable to
do PXE again, because you already have the setup where you have 2 different
XML configs during provisioning. eg, boot with kernel+initrd first to run
the installer, and then define the persistent config with boot of first
harddisk.  Since you've got 2 steps, then its easy enough to have just one
NIC and connect it to a PXE network the first time for the automated
kickstart install, and then define the persistent config with it pointing
to the public Internet.

Daniel
-- 
|: Red Hat, Engineering, London   -o-   http://people.redhat.com/berrange/ :|
|: http://libvirt.org  -o-  http://virt-manager.org  -o-  http://ovirt.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: GnuPG: 7D3B9505  -o-  F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|