This seems to be in the released Neutron at Stein, so I'm marking it as
Fix-Released
** Changed in: cloud-archive
Status: New => Invalid
** Changed in: cloud-archive/stein
Status: New => Fix Released
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https://bugs.launchpad.net/bugs/1837635
Title:
HA router state change from "standby" to "master" should be delayed
Status in Ubuntu Cloud Archive:
Invalid
Status in Ubuntu Cloud Archive queens series:
Fix Committed
Status in Ubuntu Cloud Archive rocky series:
Fix Committed
Status in Ubuntu Cloud Archive stein series:
Fix Released
Status in neutron:
Fix Released
Bug description:
Currently, when a HA state change occurs, the agent execute a series
of actions [1]: updates the metadata proxy, updates the prefix
delegation, executed L3 extension "ha_state_change" methods, updates
the radvd status and notifies this to the server.
When, in a system with more than two routers (one in "active" mode and
the others in "standby"), a switch-over is done, the "keepalived"
process [2] in each "standby" server will set the virtual IP in the HA
interface and advert it. In case that other router HA interface has
the same priority (by default in Neutron, the HA instances of the same
router ID will have the same priority, 50) but higher IP [3], the HA
interface of this instance will have the VIPs and routes deleted and
will become "standby" again. E.g.: [4]
In some cases, we have detected that when the master controller is
rebooted, the change from "standby" to "master" of the other two
servers is detected, but the change from "master" to "standby" of the
server with lower IP (as commented before) is not registered by the
server, because the Neutron server is still not accessible (the master
controller was rebooted). This status change, sometimes, is lost. This
is the situation when both "standby" servers become "master" but the
"master"-"standby" transition of one of them is lost.
1) INITIAL STATUS
(overcloud) [stack@undercloud-0 ~]$ neutron l3-agent-list-hosting-router
router
neutron CLI is deprecated and will be removed in the future. Use openstack
CLI instead.
+--------------------------------------+--------------------------+----------------+-------+----------+
| id | host |
admin_state_up | alive | ha_state |
+--------------------------------------+--------------------------+----------------+-------+----------+
| 4056cd8e-e062-4f45-bc83-d3eb51905ff5 | controller-0.localdomain | True
| :-) | standby |
| 527d6a6c-8d2e-4796-bbd0-8b41cf365743 | controller-2.localdomain | True
| :-) | standby |
| edbdfc1c-3505-4891-8d00-f3a6308bb1de | controller-1.localdomain | True
| :-) | active |
+--------------------------------------+--------------------------+----------------+-------+----------+
2) CONTROLLER 1 REBOOTED
neutron CLI is deprecated and will be removed in the future. Use openstack
CLI instead.
+--------------------------------------+--------------------------+----------------+-------+----------+
| id | host |
admin_state_up | alive | ha_state |
+--------------------------------------+--------------------------+----------------+-------+----------+
| 4056cd8e-e062-4f45-bc83-d3eb51905ff5 | controller-0.localdomain | True
| :-) | active |
| 527d6a6c-8d2e-4796-bbd0-8b41cf365743 | controller-2.localdomain | True
| :-) | active |
| edbdfc1c-3505-4891-8d00-f3a6308bb1de | controller-1.localdomain | True
| :-) | standby |
+--------------------------------------+--------------------------+----------------+-------+----------+
The aim of this bug is to make public this problem and propose a patch to
delay the transition from "standby" to "master" to let keepalived, among all
the instances running in the HA servers, to decide which one of them is the
"master" server.
[1]
https://github.com/openstack/neutron/blob/stable/stein/neutron/agent/l3/ha.py#L115-L134
[2] https://www.keepalived.org/
[3] This method is used by keepalived to define which router is predominant
and must be master.
[4] http://paste.openstack.org/show/754760/
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