Open Stack

On Thu, Jun 8, 2017 at 7:58 AM, Matt Riedemann <mriedemos at gmail.com> wrote:

> Nova stores the output of the Cinder os-initialize_connection info API in
> the Nova block_device_mappings table, and uses that later for making volume
> connections.
>
> This data can get out of whack or need to be refreshed, like if your ceph
> server IP changes, or you need to recycle some secret uuid for your ceph
> cluster.
>
> I think the only ways to do this on the nova side today are via volume
> detach/re-attach, reboot, migrations, etc - all of which, except live
> migration, are disruptive to the running guest.
>
> I've kicked around the idea of adding some sort of admin API interface for
> refreshing the BDM.connection_info on-demand if needed by an operator. Does
> anyone see value in this? Are operators doing stuff like this already, but
> maybe via direct DB updates?
>
> We could have something in the compute API which calls down to the compute
> for an instance and has it refresh the connection_info from Cinder and
> updates the BDM table in the nova DB. It could be an admin action API, or
> part of the os-server-external-events API, like what we have for the
> 'network-changed' event sent from Neutron which nova uses to refresh the
> network info cache.
>
> Other ideas or feedback here?
>
> --
>
> Thanks,
>
> Matt
>
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​The attachment_update call could do this for you, might need some slight
tweaks because I tried to make sure that we weren't having attachment
records be modified things that lived forever and were dynamic.  This
particular case seems like a descent fit though, issue the call; cinder
queries the backend to get any updated connection info and sends it back.
I'd leave it to Nova to figure out if said info has been updated or not.
Just iterate through the attachment_ids in the bdm and update/refresh each
one maybe?
​
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