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. 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 __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev