Ironic conductor Hash ring reset needs to be independent of sync_local_state periodic task

[Meghal Gosalia]

Currently, hash ring reset is done as part of sync_local_state periodic task [1].
But, for certain use cases, cloud admin will not be interested in running the sync_local_state periodic task and take over of active nodes by new conductor [2].
But, if sync_local_state is disabled, we will lose out on hash ring reset as well.
That will stop the dynamic redistribution of ironic nodes mapping to conductor [3] and will affect other periodic power sync jobs as well.

So, it would be good if hash ring rest is done as part of the mapping call itself and not tied to sync_local_state.

[1] - https://github.com/openstack/ironic/blob/master/ironic/conductor/manager.py#L1408
[2] - https://github.com/openstack/ironic/blob/master/ironic/conductor/manager.py#L1432
[3] - https://github.com/openstack/ironic/blob/master/ironic/conductor/manager.py#L1443

[Jim Rollenhagen (jim-rollenhagen)]

Talked about this in IRC some; we think the best solution is probably:

* Remove the reset from sync_local_state
* Keep track of when the ring was last refreshed
* In the code that checks if the ring is set, also check the age and rebuild if older than $config

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/235806

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/235806
Committed: https://git.openstack.org/cgit/openstack/ironic/commit/?id=fb1a67fe6bc919002e9a33aaf73a973fc48b7828
Submitter: Jenkins
Branch: master

commit fb1a67fe6bc919002e9a33aaf73a973fc48b7828
Author: Zhenguo Niu <email address hidden>
Date: Fri Oct 16 17:18:12 2015 +0800

    Move hash_ring refresh logic out of sync_local_state

    As sync_local_state periodic task can be disabled, which will lose
    out on hash ring refresh, so the refresh logic should be independent
    of it. this patch adds a updated_at to HashRingManager to track of
    when the ring was last refreshed, and when checks the ring is set,
    also check the age and rebuild if older than the new config option
    hash_ring_reset_interval which is default to 180s.

    Change-Id: Ie46dbf93b920543f99e11774a29878aaf27c3400
    Closes-Bug: #1506657

[Doug Hellmann (doug-hellmann)]

This issue was fixed in the openstack/ironic 4.3.0 release.