add bp:multi-keystone-api-version-tests

Blueprint to add support for keystone v3 throughout tempest.

Change-Id: Ib9ff5ea56d708db7fd310a4f08dadacfc0b80f54

specs/multi-keystone-api-version-tests.rst

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+::
+
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+===================================================
+ Tempest support for multiple keystone API versions
+===================================================
+
+https://blueprints.launchpad.net/tempest/+spec/multi-keystone-api-version-tests
+
+Decouple tempest from keystone version specifics and run tests with keystone v3
+
+Problem description
+===================
+
+Tempest code is tightly coupled with keystone V2 specific implementations.
+Common classes (such as rest client and tenant isolation), test base classes
+and test themselves all assume the identity service is provided by a keystone
+v2 endpoint.
+Tempest shall be able to run with a keystone V3 identity service, and newer versions
+as they become available.
+
+Proposed change
+===============
+
+A new configuration flag is introduced to specify the auth version to be used.
+A number of refactors are required to achieve this and make sure we don't need
+to change test code again when moving to different keystone API versions.
+
+Authentication are factored out in an authentication provider. Credentials are handled
+via a dedicated class, provided to tests by a credential manager.
+Clients managers receive credentials and are the sole responsible for instantiating
+clients and provide them to tests. At the moment client managers instantiate all
+available clients when created. This is unnecessary, and it leads to issues when not
+all openstack services are available for test. Client managers are thus changed to
+lazy instantiation of clients.
+
+Areas affected by refactor:
+- Rest client: move auth code to an external auth provider
+- Client managers: work with a Credentials class. Lazy load of clients
+- Tests base classes: adapt where needed to modified rest client, client manager and
+  credentials
+- Tests: adapt where needed to modified rest client, client manager and credentials
+
+Alternatives
+------------
+
+We could change all the code in place - without refactoring - adding checks for the
+configured auth version. This would still require touching a considerable chunk
+of tempest code, without the benefit for future keystone versions.
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  Andrea Frittoli <andrea.frittoli@hp.com>
+
+Milestones
+----------
+
+Target Milestone for completion:
+  Juno-1
+
+Work Items
+----------
+
+- Move auth from rest_client to auth provider
+- Provide unit tests for the new auth class
+- Refactor Manager, Credentials class everywhere
+- Client Manager provide client lazy load
+- Tenant isolation support for V3
+- Provide multi auth-version for API tests
+- Provide multi auth-version for scenario tests
+- Provide multi auth-version for CLI tests
+- Provide multi auth-version for 3rd part tests
+- Provide multi auth-version for stress framework
+
+Dependencies
+============
+
+- Python bindings and CLI are not yet all V3 ready. Some of the work in this blueprint
+  will have to be postponed until this is fixed