[Bug 1668410] Re: [SRU] Infinite loop trying to delete deleted HA router

[Corey Bryant]

Hi Hua,

Thanks for the patch. I've uploaded the package to the xenial review
queue and it is awaiting SRU review:
https://launchpad.net/ubuntu/xenial/+queue?queue_state=1&queue_text=

Corey

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Title:
  [SRU] Infinite loop trying to delete deleted HA router

Status in Ubuntu Cloud Archive:
  Invalid
Status in Ubuntu Cloud Archive mitaka series:
  Triaged
Status in neutron:
  In Progress
Status in OpenStack Security Advisory:
  Won't Fix
Status in neutron package in Ubuntu:
  Invalid
Status in neutron source package in Xenial:
  Triaged

Bug description:
  [Descriptoin]

  When deleting a router the logfile is filled up. See full log -
  http://paste.ubuntu.com/25429257/

  I can see the error 'Error while deleting router
  c0dab368-5ac8-4996-88c9-f5d345a774a6' occured 3343386 times from
  _safe_router_removed() [1]:

  $ grep -r 'Error while deleting router c0dab368-5ac8-4996-88c9-f5d345a774a6' |wc -l
  3343386

  This _safe_router_removed() is invoked by L488 [2], if
  _safe_router_removed() goes wrong it will return False, then
  self._resync_router(update) [3] will make the code
  _safe_router_removed be run again and again. So we saw so many errors
  'Error while deleting router XXXXX'.

  [1] https://github.com/openstack/neutron/blob/mitaka-eol/neutron/agent/l3/agent.py#L361
  [2] https://github.com/openstack/neutron/blob/mitaka-eol/neutron/agent/l3/agent.py#L488
  [3] https://github.com/openstack/neutron/blob/mitaka-eol/neutron/agent/l3/agent.py#L457

  [Test Case]

  That's because race condition between neutron server and L3 agent,
  after neutron server deletes HA interfaces the L3 agent may sync a HA
  router without HA interface info (just need to trigger L708[1] after
  deleting HA interfaces and before deleting HA router). If we delete HA
  router at this time, this problem will happen. So test case we design
  is as below:

  1, First update fixed package, and restart neutron-server by 'sudo
  service neutron-server restart'

  2, Create ha_router

  neutron router-create harouter --ha=True

  3, Delete ports associated with ha_router before deleting ha_router

  neutron router-port-list harouter |grep 'HA port' |awk '{print $2}' |xargs -l neutron port-delete
  neutron router-port-list harouter

  4, Update ha_router to trigger l3-agent to update ha_router info
  without ha_port into self.router_info

  neutron router-update harouter --description=test

  5, Delete ha_router this time

  neutron router-delete harouter

  [1] https://github.com/openstack/neutron/blob/mitaka-
  eol/neutron/db/l3_hamode_db.py#L708

  [Regression Potential]

  The fixed patch [1] for neutron-server will no longer return ha_router
  which is missing ha_ports, so L488 will no longer have chance to call
  _safe_router_removed() for a ha_router, so the problem has been
  fundamentally fixed by this patch and no regression potential.

  Besides, this fixed patch has been in mitaka-eol branch now, and
  neutron-server mitaka package is based on neutron-8.4.0, so we need to
  backport it to xenial and mitaka.

  $ git tag --contains 8c77ee6b20dd38cc0246e854711cb91cffe3a069
  mitaka-eol

  [1] https://review.openstack.org/#/c/440799/2/neutron/db/l3_hamode_db.py
  [2] https://github.com/openstack/neutron/blob/mitaka-eol/neutron/agent/l3/agent.py#L488

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