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Message #90519
[Bug 1956846] Re: ha router duplicated routes
Reviewed: https://review.opendev.org/c/openstack/neutron/+/865525
Committed: https://opendev.org/openstack/neutron/commit/c813b658d0e5e0c00093f90f849fcf67ddca16cf
Submitter: "Zuul (22348)"
Branch: master
commit c813b658d0e5e0c00093f90f849fcf67ddca16cf
Author: Maximilian Stinsky <maximilian.stinsky@xxxxxx>
Date: Thu Nov 24 11:40:04 2022 +0100
Fix duplicated routes exceptions
Since the train release neutron adds routes with protocol static.
Keepalived also adds the same routes with different protocols depending
on the keepalived version. This can result in duplicated routes inside
network namespaces. On l3 agent restarts those duplicate routes
then prevent the l3 agent from updating its router state
because it runs into 'RTNETLINK answers: File exists expections'
when it tries to execute 'ip route' commands.
This patch adds the same protocol static to each virtual route of
keepalived's configuration so network namespaces do not run into
duplicated routes anymore.
Closes-Bug: #1956846
Change-Id: Ic35b5d4b9110b832c10345c45ec62c0923237cfd
** Changed in: neutron
Status: In Progress => Fix Released
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https://bugs.launchpad.net/bugs/1956846
Title:
ha router duplicated routes
Status in neutron:
Fix Released
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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References
