[Bug 1993149] Re: VMs stay stuck in scheduling when rabbitmq leader unit is down

[Aqsa Malik]

Hi Corey,

Thank you for providing the fix.

I have tried the python3-oslo.messaging package (12.13.0-0ubuntu1.1) in
focal-yoga cloud environment and can confirm that it fixes the issue for
us.

Stopping any rabbitmq-server unit any number of times doesn't impact the cloud in any way and all the VMs are successfully launched.
I also checked all the logs while testing this and can see that it readily failover to another rabbitmq-server unit once a unit goes down.



** Tags removed: verification-yoga-needed
** Tags added: verification-yoga-done

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https://bugs.launchpad.net/bugs/1993149

Title:
  VMs stay stuck in scheduling when rabbitmq leader unit is down

Status in OpenStack RabbitMQ Server Charm:
  Triaged
Status in Ubuntu Cloud Archive:
  Fix Committed
Status in Ubuntu Cloud Archive yoga series:
  Fix Committed
Status in Ubuntu Cloud Archive zed series:
  Fix Committed
Status in oslo.messaging:
  New
Status in python-oslo.messaging package in Ubuntu:
  Fix Committed
Status in python-oslo.messaging source package in Jammy:
  Fix Committed
Status in python-oslo.messaging source package in Kinetic:
  Fix Committed

Bug description:
  When testing rabbitmq-server HA in our OpenStack Yoga cloud
  environment (Rabbitmq Server release 3.9/stable) we faced the
  following issues:

  - When the leader unit is down we are unable to launch any VMs and the
  launched ones stay stuck in the 'BUILD' state.

  - While checking the logs we see that several OpenStack services has
  issues in communicating with the rabbitmq-server

  - After restarting all the services using rabbitmq (like Nova, Cinder,
  Neutron etc) the issue gets resolved and the VMs can be launched
  successfully

  The corresponding logs are available at:
  https://pastebin.ubuntu.com/p/Bk3yktR8tp/

  We also observed the same for rabbitmq-server unit which is first in
  the list of 'nova.conf' file, and after restarting the concerned
  rabbitmq unit we see that scheduling of VMs work fine again.

  As this can be seen from this part of the log as well:
  "Reconnected to AMQP server on 192.168.34.251:5672 via [amqp] client with port 41922."

  ====== Ubuntu SRU Details =======

  [Impact]
  Active/active HA for rabbitmq is broken when a node goes down. 

  [Test Case]
  Deploy openstack with 3 units of rabbitmq in active/active HA.

  [Regression Potential]
  Due to the criticality of this issue, I've decided to revert the upstream change that is causing the problem as a stop-gap until a proper fix is in place. That fix came in via https://bugs.launchpad.net/oslo.messaging/+bug/1935864. As a result we may see performance degradation in polling as described in that bug.

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