Open Stack

On Jun 14, 2016 14:42, "Doug Hellmann" <doug at doughellmann.com> wrote:
>
> Excerpts from Matthew Treinish's message of 2016-06-14 15:12:45 -0400:
> > On Tue, Jun 14, 2016 at 02:41:10PM -0400, Doug Hellmann wrote:
> > > Excerpts from Matthew Treinish's message of 2016-06-14 14:21:27 -0400:
> > > > On Tue, Jun 14, 2016 at 10:57:05AM -0700, Chris Hoge wrote:
> > > > > Last year, in response to Nova micro-versioning and extension
updates[1],
> > > > > the QA team added strict API schema checking to Tempest to ensure
that
> > > > > no additional properties were added to Nova API responses[2][3].
In the
> > > > > last year, at least three vendors participating the the OpenStack
Powered
> > > > > Trademark program have been impacted by this change, two of which
> > > > > reported this to the DefCore Working Group mailing list earlier
this year[4].
> > > > >
> > > > > The DefCore Working Group determines guidelines for the OpenStack
Powered
> > > > > program, which includes capabilities with associated functional
tests
> > > > > from Tempest that must be passed, and designated sections with
associated
> > > > > upstream code [5][6]. In determining these guidelines, the
working group
> > > > > attempts to balance the future direction of development with
lagging
> > > > > indicators of deployments and user adoption.
> > > > >
> > > > > After a tremendous amount of consideration, I believe that the
DefCore
> > > > > Working Group needs to implement a temporary waiver for the
strict API
> > > > > checking requirements that were introduced last year, to give
downstream
> > > > > deployers more time to catch up with the strict micro-versioning
> > > > > requirements determined by the Nova/Compute team and enforced by
the
> > > > > Tempest/QA team.
> > > >
> > > > I'm very much opposed to this being done. If we're actually
concerned with
> > > > interoperability and verify that things behave in the same manner
between multiple
> > > > clouds then doing this would be a big step backwards. The
fundamental disconnect
> > > > here is that the vendors who have implemented out of band
extensions or were
> > > > taking advantage of previously available places to inject extra
attributes
> > > > believe that doing so means they're interoperable, which is quite
far from
> > > > reality. **The API is not a place for vendor differentiation.**
> > >
> > > This is a temporary measure to address the fact that a large number
> > > of existing tests changed their behavior, rather than having new
> > > tests added to enforce this new requirement. The result is deployments
> > > that previously passed these tests may no longer pass, and in fact
> > > we have several cases where that's true with deployers who are
> > > trying to maintain their own standard of backwards-compatibility
> > > for their end users.
> >
> > That's not what happened though. The API hasn't changed and the tests
haven't
> > really changed either. We made our enforcement on Nova's APIs a bit
stricter to
> > ensure nothing unexpected appeared. For the most these tests work on
any version
> > of OpenStack. (we only test it in the gate on supported stable
releases, but I
> > don't expect things to have drastically shifted on older releases) It
also
> > doesn't matter which version of the API you run, v2.0 or v2.1.
Literally, the
> > only case it ever fails is when you run something extra, not from the
community,
> > either as an extension (which themselves are going away [1]) or another
service
> > that wraps nova or imitates nova. I'm personally not comfortable saying
those
> > extras are ever part of the OpenStack APIs.
> >
> > > We have basically three options.
> > >
> > > 1. Tell deployers who are trying to do the right for their immediate
> > >    users that they can't use the trademark.
> > >
> > > 2. Flag the related tests or remove them from the DefCore enforcement
> > >    suite entirely.
> > >
> > > 3. Be flexible about giving consumers of Tempest time to meet the
> > >    new requirement by providing a way to disable the checks.
> > >
> > > Option 1 goes against our own backwards compatibility policies.
> >
> > I don't think backwards compatibility policies really apply to what
what define
> > as the set of tests that as a community we are saying a vendor has to
pass to
> > say they're OpenStack. From my perspective as a community we either
take a hard
> > stance on this and say to be considered an interoperable cloud (and to
get the
> > trademark) you have to actually have an interoperable product. We
slowly ratchet
> > up the requirements every 6 months, there isn't any implied backwards
> > compatibility in doing that. You passed in the past but not in the
newer stricter
> > guidelines.
> >
> > Also, even if I did think it applied, we're not talking about a change
which
> > would fall into breaking that. The change was introduced a year and
half ago
> > during kilo and landed a year ago during liberty:
> >
> > https://review.openstack.org/#/c/156130/
> >
> > That's way longer than our normal deprecation period of 3 months and a
release
> > boundary.
> >
> > >
> > > Option 2 gives us no winners and actually reduces the interoperability
> > > guarantees we already have in place.
> > >
> > > Option 3 applies our usual community standard of slowly rolling
> > > forward while maintaining compatibility as broadly as possible.
> >
> > Except in this case there isn't actually any compatibility being
maintained.
> > We're saying that we can't make the requirements for interoperability
testing
> > stricter until all the vendors who were passing in the past are able to
pass
> > the stricter version.
> >
> > >
> > > No one is suggesting that a permanent, or even open-ended, exception
> > > be granted.
> >
> > Sure, I agree an permanent or open-ended exception would be even worse.
But, I
> > still think as a community we need to draw a hard line in the sand
here. Just
> > because this measure is temporary doesn't make it any more palatable.
> >
> > By doing this, even as a temporary measure, we're saying it's ok to
call things
> > an OpenStack API when you add random gorp to the responses. Which is
something we've
> > very clearly said as a community is the exact opposite of the case,
which the
> > testing reflects. I still contend just because some vendors were
running old
> > versions of tempest and old versions of openstack where their
incompatible API
> > changes weren't caught doesn't mean they should be given pass now.
>
> Nobody is saying random gorp is OK, and I'm not sure "line in the
> sand" rhetoric is really constructive. The issue is not with the
> nature of the API policies, it's with the implementation of those
> policies and how they were rolled out.
>
> DefCore defines its rules using named tests in Tempest.  If these
> new enforcement policies had been applied by adding new tests to
> Tempest, then DefCore could have added them using its processes
> over a period of time and we wouldn't have had any issues. That's
> not what happened. Instead, the behavior of a bunch of *existing*
> tests changed. As a result, deployments that have not changed fail
> tests that they used to pass, without any action being taken on the
> deployer's part. We've moved the goal posts on our users in a way
> that was not easily discoverable, because it couldn't be tracked
> through the (admittedly limited) process we have in place for doing
> that tracking.
>
> So, we want a way to get the test results back to their existing
> status, which will then let us roll adoption forward smoothly instead
> of lurching from "pass" to "fail" to "pass".
>
> We should, separately, address the process issues and the limitations
> this situation has exposed.  That may mean changing the way DefCore
> defines its policies, or tracks things, or uses Tempest.  For
> example, in the future, we may want tie versions of Tempest to
> versions of the trademark more closely, so that it's possible for
> someone running the Mitaka version of OpenStack to continue to use
> the Mitaka version of Tempest and not have to upgrade Tempest in
> order to retain their trademark (maybe that's how it already works?).
> We may also need to consider that test implementation details may
> change, and have a review process within DefCore to help expose
> those changes to make them clearer to deployers.
>
> Fixing the process issue may also mean changing the way we implement
> things in Tempest. In this case, adding a flag helps move ahead
> more smoothly. Perhaps we adopt that as a general policy in the
> future when we make underlying behavioral changes like this to
> existing tests.  Perhaps instead we have a policy that we do not
> change the behavior of existing tests in such significant ways, at
> least if they're tagged as being used by DefCore. I don't know --
> those are things we need to discuss.
>

I had a very nice chat with Chris and talked about defcore.  Defcore does a
rolling window type validation. For X period, they validate a very specific
set of capabilities and responses.

Would a snapshot of tempest for the window makes a lot of sense (use a
branch in git parlance so that needed fixes can be applied as they crop up)
be a good solution? This is very much a case where any variation on what is
tested/results of testing within a given defcore window has an impact on
the deployers.

I want to see tempest move forward, I want defcore to continue to utilize
tempest, I don't want to see companies struggle with the trademark status
because something changed outside of the defcore window (I do not expect
tempest to hold changes or provide these greylist provisions in the future
if we have a good alternative).

I personally like the proposal, it specifically addressed the TC desire to
see defcore continue to use tempest, it addresses the immediate issue, has
a fixed window for resolution, and is not proposing this greylisting as a
general pattern to model after in the future.

Just my $0.02.

--Morgan

> Doug
>
> >
> > -Matt Treinish
> >
> > [1]
http://lists.openstack.org/pipermail/openstack-dev/2016-June/097285.html
> > >
> > > Doug
> > >
> > > >
> > > > As a user of several clouds myself I can say that having random
gorp in a
> > > > response makes it much more difficult to use my code against
multiple clouds. I
> > > > have to determine which properties being returned are specific to
that vendor's
> > > > cloud and if I actually need to depend on them for anything it
makes whatever
> > > > code I'm writing incompatible for using against any other cloud.
(unless I
> > > > special case that block for each cloud) Sean Dague wrote a good
post where a lot
> > > > of this was covered a year ago when microversions was starting to
pick up steam:
> > > >
> > > > https://dague.net/2015/06/05/the-nova-api-in-kilo-and-beyond-2
> > > >
> > > > I'd recommend giving it a read, he explains the user first
perspective more
> > > > clearly there.
> > > >
> > > > I believe Tempest in this case is doing the right thing from an
interoperability
> > > > perspective and ensuring that the API is actually the API. Not an
API with extra
> > > > bits a vendor decided to add. I don't think a cloud or product that
does this
> > > > to the api should be considered an interoperable OpenStack cloud
and failing the
> > > > tests is the correct behavior.
> > > >
> > > > -Matt Treinish
> > > >
> > > > >
> > > > > My reasoning behind this is that while the change that enabled
strict
> > > > > checking was discussed publicly in the developer community and
took
> > > > > some time to be implemented, it still landed quickly and broke
several
> > > > > existing deployments overnight. As Tempest has moved forward with
> > > > > bug and UX fixes (some in part to support the interoperability
testing
> > > > > efforts of the DefCore Working Group), using an older versions of
Tempest
> > > > > where this strict checking is not enforced is no longer a viable
solution
> > > > > for downstream deployers. The TC has passed a resolution to advise
> > > > > DefCore to use Tempest as the single source of capability
testing[7],
> > > > > but this naturally introduces tension between the competing goals
of
> > > > > maintaining upstream functional testing and also tracking lagging
> > > > > indicators.
> > > > >
> > > > > My proposal for addressing this problem approaches it at two
levels:
> > > > >
> > > > > * For the short term, I will submit a blueprint and patch to
tempest that
> > > > >   allows configuration of a grey-list of Nova APIs where strict
response
> > > > >   checking on additional properties will be disabled. So, for
example,
> > > > >   if the 'create  servers' API call returned extra properties on
that call,
> > > > >   the strict checking on this line[8] would be disabled at
runtime.
> > > > >   Use of this code path will emit a deprecation warning, and the
> > > > >   code will be scheduled for removal in 2017 directly after the
release
> > > > >   of the 2017.01 guideline. Vendors would be required so submit
the
> > > > >   grey-list of APIs with additional response data that would be
> > > > >   published to their marketplace entry.
> > > > >
> > > > > * Longer term, vendors will be expected to work with upstream to
update
> > > > >   the API for returning additional data that is compatible with
> > > > >   API micro-versioning as defined by the Nova team, and the
waiver would
> > > > >   no longer be allowed after the release of the 2017.01 guideline.
> > > > >
> > > > > For the next half-year, I feel that this approach strengthens
interoperability
> > > > > by accurately capturing the current state of OpenStack
deployments and
> > > > > client tools. Before this change, additional properties on
responses
> > > > > weren't explicitly disallowed, and vendors and deployers took
advantage
> > > > > of this in production. While this is behavior that the Nova and
QA teams
> > > > > want to stop, it will take a bit more time to reach downstream.
Also, as
> > > > > of right now, as far as I know the only client that does strict
response
> > > > > checking for Nova responses is the Tempest client. Currently,
additional
> > > > > properties in responses are ignored and do not break existing
client
> > > > > functionality. There is currently little to no harm done to
downstream
> > > > > users by temporarily allowing additional data to be returned in
responses.
> > > > >
> > > > > Thanks,
> > > > >
> > > > > Chris Hoge
> > > > > Interop Engineer
> > > > > OpenStack Foundation
> > > > >
> > > > > [1]
https://specs.openstack.org/openstack/nova-specs/specs/kilo/implemented/api-microversions.html
> > > > > [2]
http://lists.openstack.org/pipermail/openstack-dev/2015-February/057613.html
> > > > > [3] https://review.openstack.org/#/c/156130
> > > > > [4]
http://lists.openstack.org/pipermail/defcore-committee/2016-January/000986.html
> > > > > [5]
http://git.openstack.org/cgit/openstack/defcore/tree/2015.07.json
> > > > > [6]
http://git.openstack.org/cgit/openstack/defcore/tree/2016.01.json
> > > > > [7]
http://git.openstack.org/cgit/openstack/governance/tree/resolutions/20160504-defcore-test-location.rst
> > > > > [8]
http://git.openstack.org/cgit/openstack/tempest-lib/tree/tempest_lib/api_schema/response/compute/v2_1/servers.py#n39
>
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