[Libvir] Autostarting guests and networks

[Daniel Veillard]

On 2/17/07, Daniel P. Berrange <berrange at redhat.com> wrote:

> On Fri, Feb 16, 2007 at 02:51:07PM +0000, Mark McLoughlin wrote:
> > Hey,
> >       We need some way to have libvirtd automatically start guests and
> > networks.
> >
> >       We had said we should have autostart directories containing config
> > files of guests/networks which should be autostarted. One problem I see
> > with that is that we'd need a new API to define autostart configs.
> >
> >       So, I suggest we add an "autostart" flag to the toplevel element
> of the
> > configs.
> >
> >       We could discuss this one at length and I, for one, don't like
> using
> > the XML format as an API like this, but ... comments?
>
> I'm not sure that adding a flag to the XML is neccessarily the correct
> way to do this. The XML is intended to be a description of the VM's
> virtual hardware / resources. Whether a domain autostarts or not is really
> administrator defined policy which doesn't match up with intended use of
> the XML. Similar reason we don't put VCPU pinning information in the XML,
> because its local machine / administrator defined policy rather than a
> part of the VM hardware description.
>
> I think I'd probably be more inclined to add a formal API for querying
> whether a domain autostarts, and a second for setting the autostart
> flag on/off.


Agreed let's not mix policies and data. However I assume the API would allow
to define directories for autostarted configs. I guess having predefined
dirs for
such data is a common concept. And trying to hard code it like /etc/xen is
really not the best. IIRC we already have a config file now for some
daemons,
can we have such directories entries in the config file ? I guess it would
give
the flexibility required for most uses while keeping a relatively sane API
and
avoiding putting the policy in the data themselve.


> The old Xend just stuffs VM configs into a special directory to autostart,
> so we can detect that by looking for appropriate symlins, and change it
> by adding/removing the symlinks. The newer Xen 3.0.4 or later has a formal
> API for setting/querying autostart I believe, but can't remember the
> details
> just at the minute.


Do we need to match the new Xend mechanism ?

Daniel
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