py27 unit test failure: ImageMetaProps has a system dependent hash signature.

[Steven Webster]

Description
===========

Running the Nova py27 unit tests on CentOS will result in the following failures:

nova.tests.unit.objects.test_objects.TestObjectVersions.test_versions
nova.tests.unit.notifications.objects.test_notification.TestNotificationObjectVersions.test_versions

With a traceback similar to the following:

Captured traceback:
~~~~~~~~~~~~~~~~~~~
    Traceback (most recent call last):
      File "nova/tests/unit/objects/test_objects.py", line 1216, in test_versions
        'Some objects have changed; please make sure the '
      File "/src/nova/.tox/py27/lib/python2.7/site-packages/testtools/testcase.py", line 411, in assertEqual
        self.assertThat(observed, matcher, message)
      File "/src/nova/.tox/py27/lib/python2.7/site-packages/testtools/testcase.py", line 498, in assertThat
        raise mismatch_error
    testtools.matchers._impl.MismatchError: !=:
    reference = {'ImageMetaProps': '1.18-3e5975251f5843e817de68ac83274c27'}
    actual = {'ImageMetaProps': '1.18-d62a383b8cfa1779cb98014a3bf91581'}
    : Some objects have changed; please make sure the versions have been bumped, and then update their hashes here.

This was introduced as part of the following change:

https://review.openstack.org/#/c/351232/

The ImageSignatureHashType and ImageSignatureKeyType now use cursive's signature_utils to generate a hash. The problem is that these values can be different depending on the underlying capabilities of the system.
For example:

Ubuntu Xenial:

>>> signature_utils.SignatureKeyType.REGISTERED_TYPES.keys()
['RSA-PSS', 'ECC_SECP521R1', 'ECC_SECT409R1', 'ECC_SECT409K1', 'ECC_SECT571R1', 'ECC_SECP384R1', 'ECC_SECT571K1', 'DSA']

CentOS 7.3.1611:

>>> signature_utils.SignatureKeyType.REGISTERED_TYPES.keys()
['RSA-PSS', 'ECC_SECP521R1', 'ECC_SECP384R1', 'DSA']

For this reason, the values can't be reliably compared with the hardcoded hash result in nova/tests/unit/objects/test_objects.py

Steps to reproduce
==================
1. tox -e py27 on a CentOs (7) system. Other systems may suffer the same failures.

Expected result
===============
Unit tests pass

Actual result
=============
Unit tests failed

Environment
===========
1. Latest devstack, stock CentOS 7 VM, latest Nova

Logs & Configs
==============
https://pastebin.com/1rqJaTPs
http://eavesdrop.openstack.org/irclogs/%23openstack-nova/%23openstack-nova.2017-04-11.log.html#t2017-04-11T20:38:56

[Matt Riedemann (mriedem)]

This was the change:

https://review.openstack.org/#/c/351232/16/nova/objects/fields.py@430

We should probably go back to hard-coding the superset of possible expected values rather than rely on cursive building this list based on what the host supports.

[Dane Fichter (dane-fichter)]

Agreed. I'll take care of this today.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/456204

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/456204
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=d015b9804213f7a2dbde0f54256f665098007c6f
Submitter: Jenkins
Branch: master

commit d015b9804213f7a2dbde0f54256f665098007c6f
Author: dane-fichter <email address hidden>
Date: Tue Mar 28 02:43:39 2017 -0700

    Remove backend dependency for key types

    This change moves the ImageMetaProp's SignatureKeyType
    tuple from a dynamically loaded object to a static tuple,
    removing the dependency on the OpenSSL backend, which
    can vary from OS to OS.

    Depends-On: Idbda49587f3b62a0870d10817291205bde0e821e
    Change-Id: Id5191e575191d3beaa24435e98a3852dddcfe3bf
    Closes-Bug: #1681946

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 16.0.0.0b1 development milestone.