[openstack-dev] Nova config drive rebuilding

John Garbutt john at johngarbutt.com
Wed Aug 7 09:53:28 UTC 2013

I have been looking at ConfigDrive and wondering if we should update it.

ConfigDrive is only really useful if you can't/don't use DHCP.

I have thought about a (slightly messy) alternative:
* use ConfigDrive only for basic networking config on the first nic
(i.e. just enough to get to the metadata service)
* get all other data from the metadata service, once the first nic is up

Updating things like ssh-keys, etc, probably needs some sort of in
guest agent that polls for metadata changes, rather than just doing
updates on boot. We are trying to work towards deprecating the XenAPI
agent that does that sort of thing, but it could be used as a base for
a more cross hypervisor agent, if that proves to be useful direction.
It is certainly something for less dev-ops-ey/cattle VMs and more
towards the pet VM.


On 7 August 2013 10:16, Robert Collins <robertc at robertcollins.net> wrote:
> On 7 August 2013 19:41, Scott Moser <smoser at ubuntu.com> wrote:
>> Its never ok to update an 'instance-mounted' , and realistically you have
>> no way of knowing the difference between 'instance-mounted' and
>> 'instance-attached'. I'd say on reboot and shutdown you can update it, but
>> thats really hardly useful as a mechanism to get an instance new
>> information.
> I agree; by instance-mounted I was being loose in my language. I meant
> identifying when we can be sure the instance doesn't have the block
> device in use.
>> My general impression was that as we got neutron functional there was a
>> moving back towards acceptance of the metadata service.
>> The dynamic nature of a web service is *so* useful.
> Indeed :)
> -Rob
> --
> Robert Collins <rbtcollins at hp.com>
> Distinguished Technologist
> HP Converged Cloud
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