[Openstack-operators] [nova][cells] Should flavors in the API DB for cells v2 be soft-deletable?

John Garbutt john at johngarbutt.com
Fri Jan 8 12:43:23 UTC 2016

On 7 January 2016 at 19:59, Matt Riedemann <mriedem at linux.vnet.ibm.com> wrote:
> There is a cells v2 change up for review [1] which creates the flavor tables
> in the API DB.
> I noted that those table definitions include the soft-delete columns
> (deleted and deleted_at), which at the YVR summit and in other threads [2]
> we've said we're not doing anymore for new tables.
> The point raised to keep them soft-deletable is that the flavor API allows
> showing soft-deleted flavors if you know the id [3]. And you can get the
> flavor id for an instance (we always store the flavor info that was used to
> boot the instance).
> The question is, can we break that wrinkle in the API by not allow
> soft-deleting the flavor in the API DB?

On balance, I think this is OK.

> Note that in the normal nova DB, if the admin archives/purges the
> instance_types table, the wrinkle is already broken because the soft-deleted
> flavor is now hard-deleted, but that's maybe not a great justification for
> consciously removing this support in the API DB.

This is what won me over. All be it, reluctantly.

> If we made the flavor soft-deletable in the API DB, one issue is we don't
> have an in-tree entrypoint for cleaning this up (there are no archive/purge
> CLIs for the API DB). We could always add that, but it's not there right
> now.
> Another thing that came up in the cells meeting this week is that if we
> didn't make the flavor soft-deletable, we could still show the flavor
> information for a given instance via the server GET API. However, that would
> be a microversion change to show the full flavor information for the server
> rather than just the flavor id.

This is really only possible because we now store flavor info inside
every instance object.
I think before that, deleting the flavor would make some instance
operations fail.

> Thoughts? I'm cross-posting this to -dev and the -operators list to see what
> kind of user impact there would be if we didn't soft-delete flavors in the
> API DB (so you couldn't look up deleted flavors in the API).

In balance, I think we should not allow soft_delete of flavors in the API DB.

In a related note, and I thinking about a backlog spec looking at a
flavor lifecycle. Thinking about early release, to production, then
phasing out of flavors. I don't think soft delete is needed for that.


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