openstack/nova
Code Issues Proposed changes

Merge "Docs and functional test for max_local_block_devices"

Browse Source
This commit is contained in:
Zuul 2019-08-29 13:44:38 +00:00 committed by Gerrit Code Review
commit 21df56a37a
3 changed files with 41 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
doc/source/user/block-device-mapping.rst
View File

@ -220,3 +220,21 @@ mapping is valid before accepting a boot request.
.. [3] This is a feature that the EC2 API offers as well and has been in Nova
for a long time, although it has been broken in several releases. More info
can be found on `this bug <https://launchpad.net/bugs/1370250>`
FAQs
----
1. Is it possible to configure nova to automatically use cinder to back all
root disks with volumes?
No, there is nothing automatic within nova that converts a
non-boot-from-volume request to convert the image to a root volume.
Several ideas have been discussed over time which are captured in the
spec for `volume-backed flavors`_. However, if you wish to force users
to always create volume-backed servers, you can configure the API service
by setting :oslo.config:option:`max_local_block_devices` to 0. This will
result in any non-boot-from-volume server create request to fail with a
400 response.
.. _volume-backed flavors: https://review.opendev.org/511965/

13
nova/conf/compute.py
View File

@ -82,21 +82,20 @@ Possible values:
Maximum number of devices that will result in a local image being
created on the hypervisor node.
A negative number means unlimited. Setting max_local_block_devices
A negative number means unlimited. Setting ``max_local_block_devices``
to 0 means that any request that attempts to create a local disk
will fail. This option is meant to limit the number of local discs
(so root local disc that is the result of --image being used, and
any other ephemeral and swap disks). 0 does not mean that images
will be automatically converted to volumes and boot instances from
volumes - it just means that all requests that attempt to create a
local disk will fail.
(so root local disc that is the result of ``imageRef`` being used when
creating a server, and any other ephemeral and swap disks). 0 does not
mean that images will be automatically converted to volumes and boot
instances from volumes - it just means that all requests that attempt
to create a local disk will fail.
Possible values:
* 0: Creating a local disk is not allowed.
* Negative number: Allows unlimited number of local discs.
* Positive number: Allows only these many number of local discs.
(Default value is 3).
"""),
cfg.ListOpt('compute_monitors',
default=[],

17
nova/tests/functional/test_boot_from_volume.py
View File

@ -10,9 +10,12 @@
# License for the specific language governing permissions and limitations
# under the License.
import six
from nova import context
from nova import objects
from nova.tests import fixtures as nova_fixtures
from nova.tests.functional.api import client as api_client
from nova.tests.functional import integrated_helpers
from nova.tests.functional import test_servers
@ -145,3 +148,17 @@ class BootFromVolumeTest(integrated_helpers.InstanceHelperMixin,
self._verify_instance_flavor_not_zero(server_id)
# Check that request spec has not been saved with 0 root_gb
self._verify_request_spec_flavor_not_zero(server_id)
def test_max_local_block_devices_0_force_bfv(self):
"""Tests that when the API is configured with max_local_block_devices=0
a user cannot boot from image, they must boot from volume.
"""
self.flags(max_local_block_devices=0)
server = self._build_minimal_create_server_request(
self.admin_api, 'test_max_local_block_devices_0_force_bfv')
ex = self.assertRaises(api_client.OpenStackApiException,
self.admin_api.post_server,
{'server': server})
self.assertEqual(400, ex.response.status_code)
self.assertIn('You specified more local devices than the limit allows',
six.text_type(ex))