nova/releasenotes
Julia Kreger 67be896e0f [ironic] Minimize window for a resource provider to be lost
This patch is based upon a downstream patch which came up in discussion
amongst the ironic community when some operators began discussing a case
where resource providers had disappeared from a running deployment with
several thousand baremetal nodes.

Discussion amongst operators and developers ensued and we were able
to determine that this was still an issue in the current upstream code
and that time difference between collecting data and then reconciling
the records was a source of the issue. Per Arun, they have been running
this change downstream and had not seen any reoccurances of the issue
since the patch was applied.

This patch was originally authored by Arun S A G, and below is his
original commit mesage.

An instance could be launched and scheduled to a compute node between
get_uuids_by_host() call and _get_node_list() call. If that happens
the ironic node.instance_uuid may not be None but the instance_uuid
will be missing from the instance list returned by get_uuids_by_host()
method. This is possible because _get_node_list() takes several minutes to return
in large baremetal clusters and a lot can happen in that time.

This causes the compute node to be orphaned and associated resource
provider to be deleted from placement. Once the resource provider is
deleted it is never created again until the service restarts. Since
resource provider is deleted subsequent boots/rebuilds to the same
host will fail.

This behaviour is visibile in VMbooter nodes because it constantly
launches and deletes instances there by increasing the likelihood
of this race condition happening in large ironic clusters.

To reduce the chance of this race condition we call _get_node_list()
first followed by get_uuids_by_host() method.

Change-Id: I55bde8dd33154e17bbdb3c4b0e7a83a20e8487e8
Co-Authored-By: Arun S A G <saga@yahoo-inc.com>
Related-Bug: #1841481
(cherry picked from commit f84d5917c6)
(cherry picked from commit 0c36bd28eb)
2022-08-17 13:30:20 -07:00
..
notes [ironic] Minimize window for a resource provider to be lost 2022-08-17 13:30:20 -07:00
source Imported Translations from Zanata 2020-04-28 08:35:34 +00:00