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interop/working_materials/additional_properties_waiver.rst
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Additional Properties Waiver

THE ADDITIONAL PROPERTIES WAIVER IS NO LONGER ALLOWED AS OF THE 2018.01 GUIDELINE.

In mid-2015, the OpenStack QA team implemented strict response checking as an implementation detail and enforcement of Nova microversions. Microversions, in development since the Kilo release of OpenStack, were designed to allow for backwards compatible additions to the API, giving both client and server the option to request and receive responses within a known range of capabilities. In support of the interoperability goals of microversions and compatbility between OpenStack clouds, the QA team introduced strict API response checking of Nova calls as part of tempest-lib.

Prior to this change, clouds running the Nova 2.0 API could take advantage of a mechanism to add extensions to the Nova endpoint, and some also sent additional data back in their Nova responses. These clouds passed interoperability testing when the OpenStack Powered program was launched. After strict response checking was added to Tempest, these clouds failed interop testing.

To address this issue, and the challenges vendors have in updating their products to match upstream API changes, this proposal offers a means for vendors to pass the interoperability tests while proving compatibility for required capabilities.

There is a natural tension between the forward motion of upstream development and the product requirements of downstream deployments. This proposal attempts to reconcile that tension by extending the time that vendors will be required to remove additional properties and replace those features with alternatives. Possible resolutions for downstream products include, but are not limited to:

  1. Removal of all additional properties.
  2. Contributing micro-version changes upstream to capture additional properties.
  3. Using custom HTTP headers to request additional properties, to be used by custom clients or tools.
  4. Deploying additional endpoints that return unmodified responses.
  5. Remaining on the Nova v/2.0 API, which has been removed from the Newton release of OpenStack

This waiver program will cover the 2015.07, 2016.01, and 2016.08 interoperability guidelines, and give downstream vendors a year to work internally and within the ecosystem to update their products before re-verifying their products.

It's important to note that the Nova team has for two years been broadcasting their intentions[1][2][3], offering microversions as an interoperable way to add new data, and has removed the 2.0 API and extensions code from the Newton release. Although no known clients implement strict response checking (except for the Tempest client), it is clearly the direction that upsteam OpenStack developers have signaled.

Details of Waiver

  1. Products appyling for the OpenStack Powered Trademark in 2016 may request the waiver by submitting subunit data from their Tempest run that can be analyzed by the find_additional_properties.py script from the Interop WG's git repository. This script will identify tests that failed because of additional properties. The vendor will then need to modify tempest-lib[4] to remove additional checks on the impacted APIs. Development is beginning within the refstack-client project[5] to automate generation of a patch for tempest-lib.
  2. Products that use additional properties in Nova API responses will be clearly identified in the OpenStack Marketplace, with the product listing showing which APIs have included additional response data. Products using additional data will be restricted to the Nova 2.0 API.
  3. Beginning with the 2017.01 release of the Interoperability Guideline, this waiver program will no longer be in force, unless 'additional properties' is listed as an acceptable implementation using the Nova 2.0 API in the forthcoming capabilities list. All other new products must pass upstream testing.
  4. Aside from additional properties, no products may change the json API response in any other way.

[1] http://lists.openstack.org/pipermail/openstack-dev/2015-February/057613.html [2] https://specs.openstack.org/openstack/nova-specs/specs/kilo/implemented/api-microversions.html [3] http://lists.openstack.org/pipermail/openstack-dev/2015-March/059576.html [4] https://github.com/openstack/tempest/tree/master/tempest/lib/api_schema/response/compute [5] http://opendev.org/openstack/refstack-client/