openstack/glance
Code Issues Proposed changes

Attempt to not set location on non active or queued image

Browse Source 
Currently, an authorized user can set custom location string
to an image that is in any non-deleted status.

If a custom location is set to an image in ``saving`` status, it may
result in a race condition between the data stream that is trying to
save the image data to the backend and the custom location user is
attempting to set on the image record. This will result in a bad
experience for the user who is streaming the image data to Glance as
it is a better experiece to set the location after the image data has
been saved and image is in ``active`` status, in this case.

If a custom location is set to an image in ``deactivated`` status, the
purpose of setting the image to ``deactivated`` is void. This will
result in a worse experience for the security team that is trying to
evaluate the validity of the image data of the deactivated image.
Avoiding setting custom location in this case will ensure data
consistency until image is pulled out of the deactivation process.

This commit introduces the following change in behavior:
  * If an image is in ``saving`` or ``deactivated`` status, the staus of
    that image will be checked while trying to set the custom location
    and a HTTP 409 Conflict status will be retured in response to the
    user.
  * If an image is in ``active`` or ``queued`` status, setting custom
    locations on that image will be allowed so there is no change in
    behavior for this case.
  * If an image is in ``deleted`` or ``pending_delete`` status, a HTTP
    409 Conflict status will be retured, if that image is visible to the
    user (in case of admins). Otherwise, the location cannot be set
    anyway. Setting a location to a ``deleted`` image is fruitless as
    the image cannot be used. Please note ``pending_delete`` is another
    form of the ``deleted`` status and behavior in either case should be
    expected to be same.
  * If an image is in ``killed`` status, a HTTP 409 Conflict status will
    be retured. Nevertheless, it is again fruitless to attempt to set a
    location on such images as they are unusable.
  * This operation still involves the following race conditions:
     * In case where the status of the image is ``saving`` and it
       has just moved to ```active`` status, ideally setting custom
       location should be allowed however, due to lack of atomicity in
       setting image status glance will ignore setting the location and
       a 409 will be returned.
     * In case where the status of the image is ``deactivated`` and it
       has just been moved to ``active`` status, ideally setting
       custom location should be allowed however, due to lack of
       atomicity in setting image status glance will ignore setting
       the location and a 409 will be returned.
     * In case where the status of the image is ``active`` and it has
       just been moved to ``deactivated`` status, due to lack of
       atomicity in setting image status, glance may set another
       location on that image.
     * In case where the status of the image is ``queued`` and it has
       just been moved to ``saving`` status, due to lack of atomicity
       in setting image status, glance may set another location on
       that image.
     * In case where the status of the image is ``queued`` or ``active``
       and location is attempted to be set on it, if the image first
       goes into ``deleted``, ``pending_delete`` or ``killed`` status
       then the user will get a HTTP 409 Conflict status back. This
       occurs again due to lack of atomicity in setting image status.

Please note:
  * We will plan to add further granularity in setting locations to the
    images atomically in subsequent commits.
  * Fow now, though, this commit does resolve the issue of setting
    locations on an image incorrectly (in unexpected circumstances) to a
    significant degree. So, this is good progress in ensuring rightful
    use of the image locations feature.

APIImpact
DocImpact

Co-Authored-By: Mike Fedosin <mfedosin@mirantis.com>
Co-Authored-By: Nikhil Komawar <nik.komawar@gmail.com>

Change-Id: Ie463e2f30db94cde7716c83a94ec2fb0c0658c91
Lite-Spec: https://review.openstack.org/#/c/324780/
Partial-Bug: 1587985
This commit is contained in:
Mike Fedosin 2016-06-01 19:38:48 +03:00 committed by Nikhil Komawar
parent 5be7a50fe0
commit 7c7dd62689
2 changed files with 90 additions and 0 deletions
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5
glance/api/v2/images.py
View File

@ -292,6 +292,11 @@ class ImagesController(object):
"invisible.")
raise webob.exc.HTTPForbidden(explanation=msg)
if image.status not in ('active', 'queued'):
msg = _("It's not allowed to add locations if image status is "
"%s.") % image.status
raise webob.exc.HTTPConflict(explanation=msg)
pos = self._get_locations_op_pos(path_pos,
len(image.locations), True)
if pos is None:

85
glance/tests/unit/v2/test_images_resource.py
View File

@ -1571,6 +1571,91 @@ class TestImagesController(base.IsolatedUnitTest):
self.assertEqual(2, len(output.locations))
self.assertEqual(new_location, output.locations[1])
def test_update_add_locations_status_saving(self):
self.config(show_multiple_locations=True)
self.images = [
_db_fixture('1', owner=TENANT1, checksum=CHKSUM,
name='1',
disk_format='raw',
container_format='bare',
status='saving'),
]
self.db.image_create(None, self.images[0])
new_location = {'url': '%s/fake_location' % BASE_URI, 'metadata': {}}
request = unit_test_utils.get_fake_request()
changes = [{'op': 'add', 'path': ['locations', '-'],
'value': new_location}]
self.assertRaises(webob.exc.HTTPConflict,
self.controller.update, request, '1', changes)
def test_update_add_locations_status_deactivated(self):
self.config(show_multiple_locations=True)
self.images = [
_db_fixture('1', owner=TENANT1, checksum=CHKSUM,
name='1',
disk_format='raw',
container_format='bare',
status='deactivated'),
]
request = unit_test_utils.get_fake_request()
self.db.image_create(request.context, self.images[0])
new_location = {'url': '%s/fake_location' % BASE_URI, 'metadata': {}}
changes = [{'op': 'add', 'path': ['locations', '-'],
'value': new_location}]
self.assertRaises(webob.exc.HTTPConflict,
self.controller.update, request, '1', changes)
def test_update_add_locations_status_deleted(self):
self.config(show_multiple_locations=True)
self.images = [
_db_fixture('1', owner=TENANT1, checksum=CHKSUM,
name='1',
disk_format='raw',
container_format='bare',
status='deleted'),
]
self.db.image_create(None, self.images[0])
new_location = {'url': '%s/fake_location' % BASE_URI, 'metadata': {}}
request = unit_test_utils.get_fake_request()
changes = [{'op': 'add', 'path': ['locations', '-'],
'value': new_location}]
self.assertRaises(webob.exc.HTTPConflict,
self.controller.update, request, '1', changes)
def test_update_add_locations_status_pending_delete(self):
self.config(show_multiple_locations=True)
self.images = [
_db_fixture('1', owner=TENANT1, checksum=CHKSUM,
name='1',
disk_format='raw',
container_format='bare',
status='pending_delete'),
]
self.db.image_create(None, self.images[0])
new_location = {'url': '%s/fake_location' % BASE_URI, 'metadata': {}}
request = unit_test_utils.get_fake_request()
changes = [{'op': 'add', 'path': ['locations', '-'],
'value': new_location}]
self.assertRaises(webob.exc.HTTPConflict,
self.controller.update, request, '1', changes)
def test_update_add_locations_status_killed(self):
self.config(show_multiple_locations=True)
self.images = [
_db_fixture('1', owner=TENANT1, checksum=CHKSUM,
name='1',
disk_format='raw',
container_format='bare',
status='killed'),
]
self.db.image_create(None, self.images[0])
new_location = {'url': '%s/fake_location' % BASE_URI, 'metadata': {}}
request = unit_test_utils.get_fake_request()
changes = [{'op': 'add', 'path': ['locations', '-'],
'value': new_location}]
self.assertRaises(webob.exc.HTTPConflict,
self.controller.update, request, '1', changes)
def test_update_add_locations_insertion(self):
self.config(show_multiple_locations=True)
new_location = {'url': '%s/fake_location' % BASE_URI, 'metadata': {}}