scheduler report client sends allocations with value of zero, violating min_unit

[Chris Dent]

When a VM boots using non-local disk, it tries to send an allocation of 'DISK_GB': 0. This violates the default min_unit of 1 and causes an error that looks like this:

[req-858cbed4-c113-45e8-94e3-1d8ee64f9de0 488c2b05a66b441199f4c1dca7accd5b 3fa5b55ecc154427b636119f0920d252 - default default] Bad inventory
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/nova/api/openstack/placement/handlers/allocation.py", line 253, in set_allocations
    allocations.create_all()
  File "/usr/lib/python2.7/site-packages/oslo_versionedobjects/base.py", line 226, in wrapper
    return fn(self, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/nova/objects/resource_provider.py", line 1050, in create_all
    self._set_allocations(self._context, self.objects)
  File "/usr/lib/python2.7/site-packages/oslo_db/sqlalchemy/enginefacade.py", line 894, in wrapper
    return fn(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/nova/objects/resource_provider.py", line 1011, in _set_allocations
    before_gens = _check_capacity_exceeded(conn, allocs)
  File "/usr/lib/python2.7/site-packages/nova/objects/resource_provider.py", line 921, in _check_capacity_exceeded
    resource_provider=rp_uuid)
InvalidAllocationConstraintsViolated: Unable to create allocation for 'DISK_GB' on resource provider 'f9398126-d0e8-4cf8-ae45-9103a88aa13d'. The requested amount would violate inventory constraints.

The causing code is at https://github.com/openstack/nova/blob/474c2ef28234dacc658e9a78762cac66ef7fe334/nova/scheduler/client/report.py#L105

The correct fix is probably that whenever the value of any resource class is zero, don't send that resource class in the dict.

[Sylvain Bauza (sylvain-bauza)]

Yeah I think that would be the best approach for fixing that bug.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/407180

[Matt Riedemann (mriedem)]

Marking this high as it's causing issues in the ceph jobs:

http://logs.openstack.org/14/414214/12/check/gate-tempest-dsvm-full-devstack-plugin-ceph-ubuntu-xenial/511c30e/logs/screen-n-cpu.txt.gz#_2017-01-03_23_17_44_657

2017-01-03 23:17:44.657 4254 DEBUG nova.scheduler.client.report [req-eced32b1-1b58-446a-bf57-02280b9f2b4d tempest-TenantUsagesTestJSON-1895317078 tempest-TenantUsagesTestJSON-1895317078] [instance: f83871cb-c77e-4c99-833f-186db97b38b1] Sending allocation for instance {'allocations': [{'resource_provider': {'uuid': 'f8ce7899-0b48-4294-8df2-057ac325f4d2'}, 'resources': {'MEMORY_MB': 64, 'VCPU': 1, 'DISK_GB': 0}}]} _allocate_for_instance /opt/stack/new/nova/nova/scheduler/client/report.py:505
2017-01-03 23:17:44.750 4254 WARNING nova.scheduler.client.report [req-eced32b1-1b58-446a-bf57-02280b9f2b4d tempest-TenantUsagesTestJSON-1895317078 tempest-TenantUsagesTestJSON-1895317078] Unable to submit allocation for instance f83871cb-c77e-4c99-833f-186db97b38b1 (409 409 Conflict

There was a conflict when trying to complete your request.

 Unable to allocate inventory: Unable to create allocation for 'DISK_GB' on resource provider 'f8ce7899-0b48-4294-8df2-057ac325f4d2'. The requested amount would violate inventory constraints. )

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/newton
Review: https://review.openstack.org/416764

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/407180
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=200666ad19e44fb76aab29ed664767885b259822
Submitter: Jenkins
Branch: master

commit 200666ad19e44fb76aab29ed664767885b259822
Author: EdLeafe <email address hidden>
Date: Mon Dec 5 16:15:53 2016 +0000

    Do not post allocations that are zero

    When posting allocations for VMs with a non-local disk, the code was
    sending an allocation of DISK_GB = 0, which violated the min_unit
    resource constraint. Since it is pointless to enter an allocation of
    zero units, this patch removes any items in the generated allocations
    dict if the value is zero.

    Closes-Bug: #1647316

    Change-Id: I59eff4310e67ceb74086f5ade1a637f8cccec7ed

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 15.0.0.0b3 development milestone.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/416764
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=5a184889916360194fdbbdfeaf1ba1c3d75fc8f5
Submitter: Jenkins
Branch: stable/newton

commit 5a184889916360194fdbbdfeaf1ba1c3d75fc8f5
Author: EdLeafe <email address hidden>
Date: Mon Dec 5 16:15:53 2016 +0000

    Do not post allocations that are zero

    When posting allocations for VMs with a non-local disk, the code was
    sending an allocation of DISK_GB = 0, which violated the min_unit
    resource constraint. Since it is pointless to enter an allocation of
    zero units, this patch removes any items in the generated allocations
    dict if the value is zero.

    Closes-Bug: #1647316

    Change-Id: I59eff4310e67ceb74086f5ade1a637f8cccec7ed
    (cherry picked from commit 200666ad19e44fb76aab29ed664767885b259822)

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 14.0.5 release.