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[all][interop][cinder][qa] API changes with/without microversion and Tempest verification of API interoperability


On 9/16/19 6:02 AM, Ghanshyam Mann wrote:
> ---- On Mon, 16 Sep 2019 18:53:58 +0900 Ghanshyam Mann <gmann at ghanshyammann.com> wrote ----
>   > Hello Everyone,
>   >
>   > As per discussion over ML, Tempest started the JSON schema strict validation for Volume  APIs response [1].
>   > Because it may affect the interop certification, it was explained to the Interop team as well as in the Board of Director meeting[2].
>   >
>   > In Train, Tempest started implementing the validation and found an API change where the new field was added in API response without versioning[3] (Cinder has API microversion mechanism). IMO, that was not the correct way to change the API and as per API-WG guidelines[4] any field added/modified/removed in API should be with microverison(means old versions/user should not be affected by that change) and must for API interoperability.
>   >
>   > With JSON schema validation, Tempest verifies the API interoperability recommended behaviour by API-WG.  But as per IRC conversion with cinder team, we have different opinion on API interoperability and how API should be changed under microversion mechanism.  I would like to have a conclusion on this so that Tempest can verify or leave the Volume API for strict validation.
> 
> I found the same flow chart what Sean created in Nova about "when to bump microverison" in Cinder also which clearly say any addition to response need new microversion.
> - https://docs.openstack.org/cinder/latest/contributor/api_microversion_dev.html
> 
> -gmann
> 

I don't believe that it is clear that a microversion bump was required 
for the "groups" response showing up in a GET quota-sets response, and 
here's why:

This API has, since at least Havana, returned dynamic fields based on 
quotas that are assigned to volume types.  i.e.:

$ cinder --debug quota-show b73b1b7e82a247038cd01a441ec5a806
DEBUG:keystoneauth:RESP BODY: {"quota_set": {"per_volume_gigabytes": -1, 
"volumes_ceph": -1, "groups": 10, "gigabytes": 1000, "backup_gigabytes": 
1000, "snapshots": 10, "volumes_enc": -1, "snapshots_enc": -1, 
"snapshots_ceph": -1, "gigabytes_ceph": -1, "volumes": 10, 
"gigabytes_enc": -1, "backups": 10, "id": 
"b73b1b7e82a247038cd01a441ec5a806"}}

"gigabytes_ceph" is in that response because there's a "ceph" volume 
type defined, same for "gigabytes_enc", etc.

This puts this API alongside something more like listing volume types -- 
you get a list of what's defined on the deployment, not a pre-baked list 
of defined fields.

Complaints about the fact that "groups" being added without a 
microversion imply that these other dynamic fields shouldn't be in this 
response either -- but this is how this API works.

There's a lot of talk here about interoperability problems... what are 
those problems, exactly?  If we ignore Ocata and just look at Train -- 
why is this API not problematic for interoperability there, when 
requests on different clouds would return different data, depending on 
how types are configured?

It's not clear to me that rectifying the microversion concerns around 
the "groups" field is helpful without also understanding this piece, 
because if the concern is that different clouds return different fields 
for this API -- that will still happen.  We need more detail to 
understand how to address this, and what the problem is that we are 
trying to solve exactly.

(Other than the problem that Tempest currently fails on Ocata.  My 
inclination is still that the Tempest tests could just be wrong.)


>   >
>   > [1] http://lists.openstack.org/pipermail/openstack-discuss/2018-November/000358.html
>   > [2]
>   > - http://lists.openstack.org/pipermail/openstack-discuss/2019-March/003652.html
>   > - http://lists.openstack.org/pipermail/openstack-discuss/2019-March/003655.html
>   > [3] https://bugs.launchpad.net/tempest/+bug/1843762   https://review.opendev.org/#/c/439461/
>   > [4] https://specs.openstack.org/openstack/api-wg/guidelines/api_interoperability.html
>   >
>   > -gmann
>   >
> 
>