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[Keepalived <1956846@xxxxxxxxxxxxxxxxxx>]

Rudolfo,

When I was looking at the keepalived code in Neutron, I noticed a
reference to keepalived bugs [1]. If there are any bugs in keepalived
that are detrimental to Neutron, it would be helpful if they could be
reported at https://github.com/acassen/keepalived/issues so that we can
endeavour to fix them.

What is described at [1] is very strange, and the workaround seems quite
problematic to me. I am not aware what keepalived bugs are being
referred to, and I am not aware of a problem if the "primary VIP" is
changed on a reload, but if there is a problem we will fix it. It seems
quite strange to me, and problematic, that Neutron should make up and
configure an additional address, which could very easily be used by
another device on the network, and then allow keepalived to configure
that address on the system, potentially thereby causing a duplicate
address on the network.

Can we work together to try and sort out what is happening here, since
it doesn't feel right to me. I will happily work to resolve any bugs
identified in keepalived.


[1]https://github.com/openstack/neutron/blob/master/neutron/agent/linux/keepalived.py#L273-L278

** Changed in: neutron
       Status: Invalid => Incomplete

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https://bugs.launchpad.net/bugs/1956846

Title:
  ha router duplicated routes

Status in neutron:
  Incomplete

Bug description:
  In our openstack stein installation (neutron 14.4.2) we upgraded keepalived from 1.3.9 to 2.2.4.
  After that when restarting the neutron-l3-agent we saw that the router state of routers with external gatways were not able to update anymore. So we ended up with only standby routers even though keepalived is working fine and we can see one keepalived in master state.

  After debugging a bit we found the following traceback:
  ```
  Traceback (most recent call last):
    File "/usr/lib/python3/dist-packages/eventlet/hubs/hub.py", line 461, in fire_timers
      timer()
    File "/usr/lib/python3/dist-packages/eventlet/hubs/timer.py", line 59, in __call__
      cb(*args, **kw)
    File "/usr/lib/python3/dist-packages/neutron/agent/l3/ha.py", line 166, in _enqueue_state_change
      ri.set_external_gw_port_link_status(link_up=True, set_gw=True)
    File "/usr/lib/python3/dist-packages/neutron/agent/l3/ha_router.py", line 547, in set_external_gw_port_link_status
      ns_name, preserve_ips)
    File "/usr/lib/python3/dist-packages/neutron/agent/l3/router_info.py", line 750, in _external_gateway_settings
      clean_connections=True)
    File "/usr/lib/python3/dist-packages/neutron/agent/linux/interface.py", line 179, in init_router_port
      preserve_ips)
    File "/usr/lib/python3/dist-packages/neutron/agent/linux/interface.py", line 203, in set_onlink_routes
      device.route.add_onlink_route(route)
    File "/usr/lib/python3/dist-packages/neutron/agent/linux/ip_lib.py", line 662, in add_onlink_route
      self.add_route(cidr, scope='link')
    File "/usr/lib/python3/dist-packages/neutron/agent/linux/ip_lib.py", line 712, in add_route
      self._run_as_root_detect_device_not_found([ip_version], args)
    File "/usr/lib/python3/dist-packages/neutron/agent/linux/ip_lib.py", line 615, in _run_as_root_detect_device_not_found
      raise exceptions.DeviceNotFoundError(device_name=self.name)
    File "/usr/lib/python3/dist-packages/oslo_utils/excutils.py", line 220, in __exit__
      self.force_reraise()
    File "/usr/lib/python3/dist-packages/oslo_utils/excutils.py", line 196, in force_reraise
      six.reraise(self.type_, self.value, self.tb)
    File "/usr/local/lib/python3.6/dist-packages/six.py", line 719, in reraise
      raise value
    File "/usr/lib/python3/dist-packages/neutron/agent/linux/ip_lib.py", line 610, in _run_as_root_detect_device_not_found
      return self._as_root(options, tuple(args))
    File "/usr/lib/python3/dist-packages/neutron/agent/linux/ip_lib.py", line 407, in _as_root
      use_root_namespace=use_root_namespace)
    File "/usr/lib/python3/dist-packages/neutron/agent/linux/ip_lib.py", line 121, in _as_root
      namespace=namespace)
    File "/usr/lib/python3/dist-packages/neutron/agent/linux/ip_lib.py", line 129, in _execute
      log_fail_as_error=self.log_fail_as_error)
    File "/usr/lib/python3/dist-packages/neutron/agent/linux/utils.py", line 147, in execute
      returncode=returncode)
  neutron_lib.exceptions.ProcessExecutionError: Exit code: 2; Stdin: ; Stdout: ; Stderr: RTNETLINK answers: File exists
  ```

  This traceback is triggered because the routers got duplicated routes, here an example router:
  ```
  ip netns exec qrouter-76f69b0d-c9ac-4a98-851a-f74b23b2de49 ip r
  default via x.x.244.67 dev qg-6c2ee5e0-ad proto 18
  default via x.x.244.67 dev qg-6c2ee5e0-ad
  10.0.0.0/24 dev qr-15d63a29-8e proto kernel scope link src 10.0.0.10
  169.254.0.0/24 dev ha-f64d319f-ed proto kernel scope link src 169.254.0.13
  169.254.192.0/18 dev ha-f64d319f-ed proto kernel scope link src 169.254.197.12
  x.x.244.64/26 dev qg-6c2ee5e0-ad proto kernel scope link src x.x.244.116
  x.x.244.128/25 dev qg-6c2ee5e0-ad proto 18 scope link
  x.x.244.128/25 dev qg-6c2ee5e0-ad scope link
  ```

  First I thought that we hit a keepalived bug which I filed here:
  https://github.com/acassen/keepalived/issues/2076

  
  What I got to understand from the communication with pqarmitage from the issue is that keepalived is setting `proto 18/keepalived` in newer versions and I think that this breaks with neutron.

  
  So what I assume is happening here is the following.
  On a "fresh" router or a failover the qg- interface of the router is down, therefore keepalived is not able to set the virtual routes. neutron then creates the gateway routes through the set_external_gw_port_link_status function (https://opendev.org/openstack/neutron/src/tag/14.4.2/neutron/agent/l3/ha_router.py#L528) after it brings up the qg- interface. When I now restart the neutron-l3-agent it reloads keepalived which triggers keepalived to recreate the virtual_routes which it was not able to create when the qg- interface was down and because of the new functionality it creates the same route but with the addition of `proto 18` and we end up with duplicated routes. After that neutron fails on the `ip route replace` command with the RTNETLINK answers: File exists error.

  Here is a router example of getting into this state:
  backup router:
  ```
  ip netns exec qrouter-76f69b0d-c9ac-4a98-851a-f74b23b2de49 ip a
  1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
      link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
      inet 127.0.0.1/8 scope host lo
         valid_lft forever preferred_lft forever
      inet6 ::1/128 scope host
         valid_lft forever preferred_lft forever
  1755: ha-f64d319f-ed: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
      link/ether fa:16:3e:56:3f:59 brd ff:ff:ff:ff:ff:ff
      inet 169.254.197.12/18 brd 169.254.255.255 scope global ha-f64d319f-ed
         valid_lft forever preferred_lft forever
      inet6 fe80::f816:3eff:fe56:3f59/64 scope link
         valid_lft forever preferred_lft forever
  1756: qr-15d63a29-8e: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
      link/ether fa:16:3e:a9:cc:49 brd ff:ff:ff:ff:ff:ff
  1757: qg-6c2ee5e0-ad: <BROADCAST,MULTICAST> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
      link/ether fa:16:3e:d2:6c:c7 brd ff:ff:ff:ff:ff:ff

  ip netns exec qrouter-76f69b0d-c9ac-4a98-851a-f74b23b2de49 ip r
  169.254.192.0/18 dev ha-f64d319f-ed proto kernel scope link src 169.254.197.12
  ```

  After a failover to the backup node where I assume neutron is setting the gateway routes:
  ```
  ip netns exec qrouter-76f69b0d-c9ac-4a98-851a-f74b23b2de49 ip a
  1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
      link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
      inet 127.0.0.1/8 scope host lo
         valid_lft forever preferred_lft forever
      inet6 ::1/128 scope host
         valid_lft forever preferred_lft forever
  1755: ha-f64d319f-ed: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
      link/ether fa:16:3e:56:3f:59 brd ff:ff:ff:ff:ff:ff
      inet 169.254.197.12/18 brd 169.254.255.255 scope global ha-f64d319f-ed
         valid_lft forever preferred_lft forever
      inet 169.254.0.13/24 scope global ha-f64d319f-ed
         valid_lft forever preferred_lft forever
      inet6 fe80::f816:3eff:fe56:3f59/64 scope link
         valid_lft forever preferred_lft forever
  1756: qr-15d63a29-8e: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
      link/ether fa:16:3e:a9:cc:49 brd ff:ff:ff:ff:ff:ff
      inet 10.0.0.10/24 scope global qr-15d63a29-8e
         valid_lft forever preferred_lft forever
      inet6 fe80::f816:3eff:fea9:cc49/64 scope link nodad
         valid_lft forever preferred_lft forever
  1757: qg-6c2ee5e0-ad: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
      link/ether fa:16:3e:d2:6c:c7 brd ff:ff:ff:ff:ff:ff
      inet x.x.244.116/26 scope global qg-6c2ee5e0-ad
         valid_lft forever preferred_lft forever
      inet6 x.x:1003::22b/64 scope global nodad
         valid_lft forever preferred_lft forever
      inet6 fe80::f816:3eff:fed2:6cc7/64 scope link nodad
         valid_lft forever preferred_lft forever

  
  ip netns exec qrouter-76f69b0d-c9ac-4a98-851a-f74b23b2de49 ip r
  default via x.x.244.67 dev qg-6c2ee5e0-ad
  10.0.0.0/24 dev qr-15d63a29-8e proto kernel scope link src 10.0.0.10
  169.254.0.0/24 dev ha-f64d319f-ed proto kernel scope link src 169.254.0.13
  169.254.192.0/18 dev ha-f64d319f-ed proto kernel scope link src 169.254.197.12
  x.x.244.64/26 dev qg-6c2ee5e0-ad proto kernel scope link src x.x.244.116
  x.x.244.128/25 dev qg-6c2ee5e0-ad scope link
  ```

  And then after a neutron-l3-agent restart which triggers a keepalived reload:
  ```
  ip netns exec qrouter-76f69b0d-c9ac-4a98-851a-f74b23b2de49 ip r
  default via x.x.244.67 dev qg-6c2ee5e0-ad proto 18
  default via x.x.244.67 dev qg-6c2ee5e0-ad
  10.0.0.0/24 dev qr-15d63a29-8e proto kernel scope link src 10.0.0.10
  169.254.0.0/24 dev ha-f64d319f-ed proto kernel scope link src 169.254.0.13
  169.254.192.0/18 dev ha-f64d319f-ed proto kernel scope link src 169.254.197.12
  x.x.244.64/26 dev qg-6c2ee5e0-ad proto kernel scope link src x.x.244.116
  x.x.244.128/25 dev qg-6c2ee5e0-ad proto 18 scope link
  x.x.244.128/25 dev qg-6c2ee5e0-ad scope link

  ```

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