Comment 29 for bug 1739646

Reviewed: https://review.openstack.org/563719
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=8392c7f2656ae624877e3df539681c0a8f8b4926
Submitter: Zuul
Branch: stable/ocata

commit 8392c7f2656ae624877e3df539681c0a8f8b4926
Author: Matt Riedemann <email address hidden>
Date: Fri Apr 13 13:44:33 2018 -0400

    Add policy rule to block image-backed servers with 0 root disk flavor

    This adds a new policy rule which defaults to behave in a
    backward compatible way, but will allow operators to enforce
    that servers created with a zero disk flavor must also be
    volume-backed servers.

    Allowing users to upload their own images and create image-backed
    servers on local disk with zero root disk size flavors can be
    potentially hazardous if the size of the image is unexpectedly
    large, since it can consume the local disk (or shared storage pool).

    It should be noted that disabling the new policy rule will
    result in a non-backward compatible API behavior change and no
    microversion is being introduced for this because enforcement via
    a new microversion would not close the security gap on any previous
    microversions.

    Related compute API reference and user documentation is updated
    to mention the policy rule along with a release note since
    this is tied to a security bug, which will be backported to stable
    branches.

    Conflicts:
          api-ref/source/parameters.yaml
          doc/source/admin/flavors2.rst
          nova/policies/servers.py
          nova/tests/functional/wsgi/test_servers.py

    NOTE(mriedem): The api-ref/source/parameters.yaml conflict is due
    to If646149efb7eec8c90bf7d07c39ff4c495349941 not being in Pike.
    The doc/source/admin/flavors2.rst conflict is due to the doc
    not being in Ocata - it was migrated from the central admin-guide
    in Ifa0039e270e54ea2fb58ab18ce6724e5e8e061a1.
    The nova/policies/servers.py conflict is due to two changes in Pike:
    I17b6ca6e17c777ae7d337bf70ec4774ffe5187a8 and
    I050c4f5f19aa79a682e076cc3e47eba597f272dd. The DocumentedRuleDefault
    class was added to oslo.policy starting in 1.21.1 in Pike which is
    newer than what stable/ocata supports in global-requirements so we
    can't use it in this backport.
    The nova/tests/functional/wsgi/test_servers.py conflict is due to
    Ifcaaf285c8f98a1d0e8bbbc87b2f57fbce057346 and
    I294c54e5a22dd6e5b226a4b00e7cd116813f0704 not being in Ocata.

    Change-Id: Id67e1285a0522474844de130c9263e11868f67fb
    Closes-Bug: #1739646
    (cherry picked from commit 763fd62464e9a0753e061171cc1fd826055bbc01)
    (cherry picked from commit 7bcd581c78bb5916bf4b52e213322e7b56283572)
    (cherry picked from commit 0bf75621bbd25d4ce8a3588f112cf714891556eb)