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[Bug 1999678] [NEW] Static route can get stuck in the router snat namespace

 

Public bug reported:

I ran into a problem where a static route just gets stuck in the snat namepsace, even when removing all static routes from a distributed router with ha enabled.
Here is a simple demo from my devstack setup:

[root@node0 ~]# openstack network create private
[root@node0 ~]# openstack subnet create private --network private --subnet-range 192.168.10.0/24 --dhcp --gateway 192.168.10.1
[root@node0 ~]# openstack router create r1 --external-gateway public --distributed --ha
[root@node0 ~]# openstack router add subnet r1 private
[root@node0 ~]# openstack router set r1 --route destination=8.8.8.0/24,gateway=192.168.10.100 --route destination=8.8.8.0/24,gateway=192.168.10.200

After multipath route was added, snat-ns routes look like this:

[root@node0 ~]# ip netns exec snat-dcbec74b-2003-4447-8854-524d918260ac ip r
default via 10.136.16.1 dev qg-94c43336-56 proto keepalived
8.8.8.0/24 via 192.168.10.200 dev sg-dcf4a20b-8a proto keepalived
8.8.8.0/24 via 192.168.10.100 dev sg-dcf4a20b-8a proto keepalived
8.8.8.0/24 via 192.168.10.100 dev sg-dcf4a20b-8a proto static
10.136.16.0/20 dev qg-94c43336-56 proto kernel scope link src 10.136.17.171
169.254.0.0/24 dev ha-11b5b7d3-4e proto kernel scope link src 169.254.0.21
169.254.192.0/18 dev ha-11b5b7d3-4e proto kernel scope link src 169.254.195.228
192.168.10.0/24 dev sg-dcf4a20b-8a proto kernel scope link src 192.168.10.228
[root@node0 ~]#

Note that there is only one 'static' route added by neutron and no multipath route.
And two routes with 'proto keepalived' that have been added by keepalived process.
Now delete all routes and check the routes inside snat-ns, the route is still there:

[root@node0 ~]# openstack router set r1 --no-route
[root@node0 ~]# ip netns exec snat-dcbec74b-2003-4447-8854-524d918260ac ip r
default via 10.136.16.1 dev qg-94c43336-56 proto keepalived
8.8.8.0/24 via 192.168.10.100 dev sg-dcf4a20b-8a proto static
10.136.16.0/20 dev qg-94c43336-56 proto kernel scope link src 10.136.17.171
169.254.0.0/24 dev ha-11b5b7d3-4e proto kernel scope link src 169.254.0.21
169.254.192.0/18 dev ha-11b5b7d3-4e proto kernel scope link src 169.254.195.228
192.168.10.0/24 dev sg-dcf4a20b-8a proto kernel scope link src 192.168.10.228
[root@node0 ~]#

** Affects: neutron
     Importance: Undecided
         Status: In Progress

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https://bugs.launchpad.net/bugs/1999678

Title:
  Static route can get stuck in the router snat namespace

Status in neutron:
  In Progress

Bug description:
  I ran into a problem where a static route just gets stuck in the snat namepsace, even when removing all static routes from a distributed router with ha enabled.
  Here is a simple demo from my devstack setup:

  [root@node0 ~]# openstack network create private
  [root@node0 ~]# openstack subnet create private --network private --subnet-range 192.168.10.0/24 --dhcp --gateway 192.168.10.1
  [root@node0 ~]# openstack router create r1 --external-gateway public --distributed --ha
  [root@node0 ~]# openstack router add subnet r1 private
  [root@node0 ~]# openstack router set r1 --route destination=8.8.8.0/24,gateway=192.168.10.100 --route destination=8.8.8.0/24,gateway=192.168.10.200

  After multipath route was added, snat-ns routes look like this:

  [root@node0 ~]# ip netns exec snat-dcbec74b-2003-4447-8854-524d918260ac ip r
  default via 10.136.16.1 dev qg-94c43336-56 proto keepalived
  8.8.8.0/24 via 192.168.10.200 dev sg-dcf4a20b-8a proto keepalived
  8.8.8.0/24 via 192.168.10.100 dev sg-dcf4a20b-8a proto keepalived
  8.8.8.0/24 via 192.168.10.100 dev sg-dcf4a20b-8a proto static
  10.136.16.0/20 dev qg-94c43336-56 proto kernel scope link src 10.136.17.171
  169.254.0.0/24 dev ha-11b5b7d3-4e proto kernel scope link src 169.254.0.21
  169.254.192.0/18 dev ha-11b5b7d3-4e proto kernel scope link src 169.254.195.228
  192.168.10.0/24 dev sg-dcf4a20b-8a proto kernel scope link src 192.168.10.228
  [root@node0 ~]#

  Note that there is only one 'static' route added by neutron and no multipath route.
  And two routes with 'proto keepalived' that have been added by keepalived process.
  Now delete all routes and check the routes inside snat-ns, the route is still there:

  [root@node0 ~]# openstack router set r1 --no-route
  [root@node0 ~]# ip netns exec snat-dcbec74b-2003-4447-8854-524d918260ac ip r
  default via 10.136.16.1 dev qg-94c43336-56 proto keepalived
  8.8.8.0/24 via 192.168.10.100 dev sg-dcf4a20b-8a proto static
  10.136.16.0/20 dev qg-94c43336-56 proto kernel scope link src 10.136.17.171
  169.254.0.0/24 dev ha-11b5b7d3-4e proto kernel scope link src 169.254.0.21
  169.254.192.0/18 dev ha-11b5b7d3-4e proto kernel scope link src 169.254.195.228
  192.168.10.0/24 dev sg-dcf4a20b-8a proto kernel scope link src 192.168.10.228
  [root@node0 ~]#

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