[openstack-dev] [cinder] [driver] DB operations

Duncan Thomas duncan.thomas at gmail.com
Fri Dec 19 09:20:55 UTC 2014

So our general advice has historical been 'drivers should not be accessing
the db directly'. I haven't had chance to look at your driver code yet,
I've been on vacation, but my suggestion is that if you absolutely must
store something in the admin metadata rather than somewhere that is covered
by the model update (generally provider location and provider auth) then
writing some helper methods that wrap the context bump and db call would be
better than accessing it directly from the driver.

Duncan Thomas
On Dec 18, 2014 11:41 PM, "Amit Das" <amit.das at cloudbyte.com> wrote:

> Hi Stackers,
> I have been developing a Cinder driver for CloudByte storage and have come
> across some scenarios where the driver needs to do create, read & update
> operations on cinder database (volume_admin_metadata table). This is
> required to establish a mapping between OpenStack IDs with the backend
> storage IDs.
> Now, I have got some review comments w.r.t the usage of DB related
> operations esp. w.r.t raising the context to admin.
> In short, it has been advised not to use "*context.get_admin_context()*".
> https://review.openstack.org/#/c/102511/15/cinder/volume/drivers/cloudbyte/cloudbyte.py
> However, i get errors trying to use the default context as shown below:
> *2014-12-19 12:18:17.880 TRACE oslo.messaging.rpc.dispatcher   File
> "/opt/stack/cinder/cinder/db/sqlalchemy/api.py", line 103, in
> is_admin_context*
> *2014-12-19 12:18:17.880 TRACE oslo.messaging.rpc.dispatcher     return
> context.is_admin*
> *2014-12-19 12:18:17.880 TRACE oslo.messaging.rpc.dispatcher
> AttributeError: 'module' object has no attribute 'is_admin'*
> So what is the proper way to run these DB operations from within a driver ?
> Regards,
> Amit
> *CloudByte Inc.* <http://www.cloudbyte.com/>
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