[openstack-dev] [qa][cinder][ceph] should Tempest tests the backend specific feature?

Andrea Frittoli andrea.frittoli at gmail.com
Wed May 3 13:14:18 UTC 2017


On Tue, May 2, 2017 at 4:56 PM Sean McGinnis <sean.mcginnis at gmx.com> wrote:

> On Tue, May 02, 2017 at 03:36:20PM +0200, Jordan Pittier wrote:
> > On Tue, May 2, 2017 at 7:42 AM, Ghanshyam Mann <ghanshyammann at gmail.com>
> > wrote:
> >
> > > In Cinder, there are many features/APIs which are backend specific and
> > > will return 405 or 501 if same is not implemented on any backend [1].
> > > If such tests are implemented in Tempest, then it will break some gate
> > > where that backend job is voting. like ceph job in glance_store gate.
> > >
> > > There been many such cases recently where ceph jobs were broken due to
> > > such tests and recently it is for force-delete backup feature[2].
> > > Reverting force-delete tests in [3]. To resolve such cases at some
> > > extend, Jon is going to add a white/black list of tests which can run
> > > on ceph job [4] depends on what all feature ceph implemented. But this
> > > does not resolve it completely due to many reason like
> > > 1. External use of Tempest become difficult where user needs to know
> > > what all tests to skip for which backend
> > > 2. Tempest tests become too specific to backend.
> > >
> > > Now there are few options to resolve this:
> > > 1. Tempest should not tests such API/feature which are backend
> > > specific like mentioned by api-ref like[1].
> > >
> > So basically, if one of the 50 Cinder driver doesn't support a feature,
> we
> > should never test that feature ? What about the 49 other drivers ? If a
> > feature exists and can be tested in the Gate (with whatever default
> > config/driver is shipped) then I think we should test it.
> >
> 50? Over 100 as of Ocata.
>
> Well, is tempest's purpose in life to provide complete gate test coverage,
> or is tempest's purpose in life to give operators a tool to validate that
> their deployment is working as expected?
>

Neither.

Tempest is used for several different purposes, but I would say it was never
meant to ensure 100% coverage of the API. It is used by many operators to
validate their deployments, even if that part is better achieved via the
"scenario" tests, as opposed to the "API" tests.

Main use cases for Tempest are:
- integration (cross-service) testing in the gate
- help to ensure API backward compatibility / stability
- home for interoperability tests


> In attempting to do things in the past, I've received push back based on
> the argument that it was the latter. For this reason, in-tree tempest tests
> were added to Cinder to give us a way to get better test coverage for our
> own sake.
>

There are several use cases for in-tree tests.
Some examples:

Test that provide very little cross-service validation (e.g. most API
negative
tests) do not need to be in Tempest. Running a full cloud is expensive
resource and time-wise, and it's not the best test environment to run a
large
combination of negative test cases.

Many tests cannot be driven via API. It's very hard for instance to test
any transient resource state via API, since there's not enough control via
the API.

Scheduler tests are not best implemented via API as well, since they often
require
several nodes and resources when executed in a full cloud environment.


> Now that this is all in place, I think it's working well and I would like
> to see it continue that way. IMO, tempest proper should not have anything
> that isn't universally applicable to real world deployments. Not just for
> things like Ceph, but things like the manage/unmanage backend specific
> tests that were added and broke a large majority of third party CI.
>

Is there a policy in Cinder that a backend must implement a certain set of
APIs? If so we could think of testing only that set of APIs in Tempest, so
that
any app developer knows that he/she can rely on that minimum set of APIs.

If the list of APIs is not constrained on cinder side, the next driver
could come
along that does not support an API, and then we would have to stop testing
it
in Tempest - which is not an option.

Another point is that API that rely on services other than nova are best
tested
in Tempest, so that the tests run in the gate of other services as well -
or at
least the cinder functional test job should run against the other services
as well.


>
> Backend specific things should not be part of tempest in my opinion. We
> should cover those things through in-tree tempest plugins and our own
> testing.
> >
> > > 2. Tempest test can be disabled/skip based on backend. - This is not
> > > good idea as it increase config options and overhead of setting those.
> > >
> > Using regex and blacklist, any 3rd party CI can skip any test based on
> the
> > test ID. Without introducing a config flag. See:
> >
> https://github.com/openstack-infra/project-config/blob/1cea31f402b6b0cccc47cde203c12184b5392c90/jenkins/jobs/devstack-gate.yaml#L1871
> >
> >
> > > 3. Tempest test can verify behavior with if else condition as per
> > > backend. This is bad idea and lose the test strength.
> > >
> > Yeah, that's bad.
> >
> > >
> > > IMO options 1 is better options. More feedback are welcome.
> >
> >
> > > ..1 https://developer.openstack.org/api-ref/block-storage/v3/?
> > > expanded=force-delete-a-backup-detail#force-delete-a-backup
> > > ..2 https://bugs.launchpad.net/glance/+bug/1687538
> > > ..3 https://review.openstack.org/#/c/461625/
> > > ..4 http://lists.openstack.org/pipermail/openstack-dev/2017-
> > > April/115229.html
> > >
> > > -gmann
>
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