[Openstack-operators] [openstack-dev] [nova] The createBackup API

melanie witt melwittt at gmail.com
Wed Apr 4 19:04:01 UTC 2018


Operator feedback wanted: do you have users that pass rotation parameter 
'0' to the createBackup API in order to delete backups? Do you have 
users using the createBackup API in general?

On Fri, 30 Mar 2018 10:44:40 +0800, Alex Xu wrote:
> There is spec proposal to fix a bug of createBackup API with 
> microversion. (https://review.openstack.org/#/c/511825/)
> When rotation parameter is '0', the createBackup API just do a snapshot, 
> and then delete all the snapshots. That is meaningless behavier.

Agreed that '0' is meaningless in the context of 'createBackup' but as a 
side-effect, it allows users to purge old backups on-demand.

> But there is thing hope to get wider suggestion. Since we said before 
> all the nova API should be primitive, the API shouldn't be another wrap 
> of another API.
> So the createBackup sounds like just using the createImage API to create 
> a snapshot, and upload the snapshot into the glance with index number in 
> the image name, and rotation the image in after each snapshot.
> So it should be something can be done by the client scrips to do same 
> thing with createImage API.
> We have two options here:
> #1. fix the bug with a microversion. And we aren't sure any people 
> really use '0' in the real life. But we use microversion to fix that 
> bug, not sure it is worth.

I think this is the key point -- are there users who have been using '0' 
to the createBackup API in order to delete backups? If so, then I would 
be inclined to go ahead and fix the issue in our API with a microversion 
(disallow '0' for createBackup and then add a deleteBackups server action).

My rationale is that if people are actively using it, let's just fix it 
since it's nearly already there. The only problem with how it currently 
works is that '0' needlessly creates a backup that it will turn around 
and delete. The fix would be small and straightforward as it would just 
add schema validation for '0' on createBackup and then the new 
deleteBackups action would be an alias for deleting things (we already 
have the delete logic happening for '0').

> #2. deprecate the backup API with a microversion, leave the bug along. 
> Document that how the user can do that in the client script.
> Looking for your comments.

If there isn't broader use of the API, then I'd be in favor of 
deprecating it.


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