[openstack-dev] Nova config drive rebuilding

Ian Wells ijw.ubuntu at cack.org.uk
Fri Aug 9 01:09:16 UTC 2013

On 7 August 2013 11:53, John Garbutt <john at johngarbutt.com> wrote:
> 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

This depends on your instance having a route to the metadata server,
which may or may not be the case.  And, of course, it's always an
option, even with the current config disk, to use a combined approach
- you can choose to ignore everything but the network settings from
the config disk if you wish.

I like config disks, I use config disks, but I wouldn't want to make
them something they aren't.  A static filesystem (and, practically
speaking, any FS you've handed over to an instance is static) is not
the way to communicate dynamic data to an instance.  Any attempt to do
so is likely to be awkward - for instance, a config drive that changes
on stop/start is limited, and yet probably also the best you can
manage.  If you want a backchannel to your instance, then you probably
really do want a(nother) network interface.

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