Open Stack

On Wed, Jan 30, 2013 at 02:13:29PM +0000, Daniel P. Berrange wrote:
> I have a need to be able to provide custom kernel command line args per
> VM instance at boot time. For example, if glance is storing a kernel and
> initrd pair associated with the Fedora installer, it is neccessary to
> also provide a command line arg to tell the installer where to download
> a kickstart automation script from, or where the install tree is located.
> While some of this data could be stored in glance as metadata properties
> against the 'kernel' image, some it is inherantly data that changes per
> VM instance spawned. Thus I need some way to provide it at 'nova boot'
> time.
> 
>   https://blueprints.launchpad.net/nova/+spec/custom-kernel-args
>   http://wiki.openstack.org/LibvirtCustomKernelArgs
> 
> Two approaches come to mind for me
> 
>  - Add an explicit 'kernel-args' parameter to the 'nova boot' command
>    and corresponding REST/RPC APIs
> 
>  - Add a generic 'properties' dict parameter to the 'nova boot' command
>    and corresponding REST/RPC APIs, and define a standard property
>    name 'kernel-args'.
> 
> I'm figuring the latter would be preferrable since it gives us an
> extensible framework for instance metadata.  NB, this is separate
> from metadata that you can alrady provide to feed through to the
> cloud-init services via config-drive / metadata service. It is
> metadata intended for interpretation by Nova itself, where as the
> existing metadata is for interpretation by the guest OS.

Does anyone else have an opinion on the design of this proposal ?

Daniel
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