[Bug 1602057] [NEW] [SRU] (libvirt) KeyError updating resources for some node, guest.uuid is not in BDM list

[Launchpad Bug Tracker]

You have been subscribed to a public bug by Edward Hope-Morley (hopem):

[Impact]

There currently exists a race condition whereby the compute
resource_tracker periodic task polls extant instances and checks their
BDMs which can occur prior to any mappings having yet been created e.g.
root disk mapping for new instances. This patch ensures that instances
without any BDMs are skipped.

[Test Case]
  * deploy Openstack Mitaka with debug logging enabled (not essential but helps)

  * create an instance

  * delete its BDMs - pastebin.ubuntu.com/24287419/

  * watch /var/log/nova/nova-compute.log on hypervisor hosting instance
and wait for next resource_tracker tick

  * ensure that exception mentioned in LP does not occur (happens after
"Auditing locally available compute resources for node")

[Regression Potential]

The resource tracker information is used by the scheduler when deciding
which compute hosts are able to have an instances scheduled to them. In
this case the resource tracker would be skipping instances that would
contribute to disk overcommit ratios. As such it is possible that that
scheduler will have momentarily skewed information about resource
consumption on that compute host until the next resource_tracker tick.
Since the likelihood of this race condition occurring is hopefully slim
and provided that users have a reasonable frequency for the
resource_tracker, the likelihood of this becoming a long term problem is
low since the issue will always be corrected by a subsequent tick
(although if the compute host in question were saturated that would not
be fixed until an instances was deleted or migrated).

--------

2016-07-12 09:54:36.021 10056 ERROR nova.compute.manager [req-d5d5d486-b488-4429-bbb5-24c9f19ff2c0 - - - - -] Error updating resources for node controller.
2016-07-12 09:54:36.021 10056 ERROR nova.compute.manager Traceback (most recent call last):
2016-07-12 09:54:36.021 10056 ERROR nova.compute.manager   File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 6726, in update_available_resource
2016-07-12 09:54:36.021 10056 ERROR nova.compute.manager     rt.update_available_resource(context)
2016-07-12 09:54:36.021 10056 ERROR nova.compute.manager   File "/usr/lib/python2.7/site-packages/nova/compute/resource_tracker.py", line 500, in update_available_resource
2016-07-12 09:54:36.021 10056 ERROR nova.compute.manager     resources = self.driver.get_available_resource(self.nodename)
2016-07-12 09:54:36.021 10056 ERROR nova.compute.manager   File "/usr/lib/python2.7/site-packages/nova/virt/libvirt/driver.py", line 5728, in get_available_resource
2016-07-12 09:54:36.021 10056 ERROR nova.compute.manager     disk_over_committed = self._get_disk_over_committed_size_total()
2016-07-12 09:54:36.021 10056 ERROR nova.compute.manager   File "/usr/lib/python2.7/site-packages/nova/virt/libvirt/driver.py", line 7397, in _get_disk_over_committed_size_total
2016-07-12 09:54:36.021 10056 ERROR nova.compute.manager     local_instances[guest.uuid], bdms[guest.uuid])
2016-07-12 09:54:36.021 10056 ERROR nova.compute.manager KeyError: '0a5c5743-9555-4dfd-b26e-198449ebeee5'
2016-07-12 09:54:36.021 10056 ERROR nova.compute.manager

** Affects: cloud-archive
     Importance: Undecided
         Status: Fix Released

** Affects: cloud-archive/mitaka
     Importance: Medium
     Assignee: Edward Hope-Morley (hopem)
         Status: Triaged

** Affects: cloud-archive/newton
     Importance: Medium
         Status: Fix Released

** Affects: nova
     Importance: Medium
     Assignee: Dan Smith (danms)
         Status: Fix Released

** Affects: nova/mitaka
     Importance: Undecided
     Assignee: Edward Hope-Morley (hopem)
         Status: Won't Fix

** Affects: nova/newton
     Importance: Medium
     Assignee: Lee Yarwood (lyarwood)
         Status: Fix Committed

** Affects: nova (Ubuntu)
     Importance: Undecided
         Status: Confirmed

** Affects: nova (Ubuntu Xenial)
     Importance: Undecided
     Assignee: Edward Hope-Morley (hopem)
         Status: Confirmed


** Tags: canonical-bootstack libvirt sts sts-sru-needed
-- 
[SRU] (libvirt) KeyError updating resources for some node, guest.uuid is not in BDM list
https://bugs.launchpad.net/bugs/1602057
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