[one-users] Not setting a default i686 arch in vmm_exec_kvm.conf ? - Was: Re: Mandatory attributes with default value ?

[Olivier Berger]

On Mon, 21 May 2012 23:21:31 +0200, "Ruben S. Montero" <rsmontero at opennebula.org> wrote:
> >
> > Hmmm... so, the intent is to have a same template which could be
> > deployed on hosts using different hypervisors on the same cloud ? I'm
> > not sure I understand the rationale. Could you elaborate a bit more ?
> >
> 
> You may have a cluster with Xen and KVM hypervisors for example a simple
> 
> MEMORY = 128
> CPU = 1
> 
> DISK = [ IMAGE = "Debian" ]
> 
> will do  for both of them, however we may need some OS values for KVM
> like arch, or we may need an specific ramdisk/kernel for a
> para-virtualized Xen.
> 
> Moreover, in a hybrid setup the above template can be complemented with
> 
> EC2 = [ AMI="ami-00bafcb5",
>              KEYPAIR="gsg-keypair",
>              INSTANCETYPE=m1.small]
> 
> where ami-00bafcb5 is your EC2 equivalent for the IMAGE "Debian".
> 
> So we will need different hypervisor values for the template depending
> on the target hypervisor, KVM, Xen or EC2 Cloud
> 

I'm still not sure I do understand the intended use case that you
describe, but AFAICT, things happen this way : if vmm_exec_kvm.conf (KVM
specific) doesn't contain any OS:ARCH, and if the specific target
doesn't either, then an error will be reported upon libvirt deployment
file generation ('No ARCH defined and no default provided.'), which is
indeed the expected behaviour for a mandatory attribute.

Now, if the default vmm_exec_kvm.conf provided by One contains (as
currently is) a default i686 arch, this default value may not suit all
cases, including some failed boots of Linux, as I experienced.

So... my impression is that maybe no such default OS:ARCH should be
initialized in the provided default vmm_exec_kvm.conf, letting the
administrator uncomment a proposed default in the included docs inside
it, if needed. I fear to imagine everyone would use i686 arches VMs on
i686 nodes...
In the most general case, one would then set one explicitely in each VM
templates, and only in particular cases, like the one you described
(same template, multiple hypervisors) or where this can be defined for
all VMs with a default, would and admin 'factorize' the setting with a
default in her vmm_exec_kvm.conf.

Would it make sense ?

Thanks for the investigation of the mandatory settings checking code,
and your opinion.

Best regards,
-- 
Olivier BERGER 
http://www-public.it-sudparis.eu/~berger_o/ - OpenPGP-Id: 2048R/5819D7E8
Ingenieur Recherche - Dept INF
Institut Mines-Telecom, Telecom SudParis, Evry (France)