nova-compute will try to re-plug the vif even if it exists for vhostuser port.

Automatically discovered version mitaka in description. If this is incorrect, please update the description to include 'nova version: ...'

There are no currently open reviews on this bug, changing the status back to the previous state and unassigning. If there are active reviews related to this bug, please include links in comments.

What real world scenario would you expect to expose a situation where the neutron environment is turned off and nova-compute is restarted? This seems pretty synthetic, and the fact that it recovers ones the neutron agent restarts seems like most of the environment is working as expected.

This issue is valid for mitaka and newton which are both using OVS dpdkvhostuser port, deleting the port is going to make instance losing connectivity.

After newton we have deprecated usage dpdkvhostuser to use dpdkvhostuserclient. Not sure whether we want fix it upstream so?

Not sure if this is the same issue but you can reproduce this by simply restarting nova-compute. With a DevStack-based deployment, run:

  $ sudo service <email address hidden> restart

This will result in the following ovs-related logs in journalctl:

  $ journalctl -a /usr/sbin/ovs-vswitchd /usr/bin/ovs-vsctl -a --follow
  Mar 05 14:01:12 localhost.localdomain ovs-vsctl[11616]: ovs|00001|vsctl|INFO|Called as ovs-vsctl -- --may-exist add-br br-int -- set Bridge br-int datapath_type=netdev
  Mar 05 14:01:12 localhost.localdomain ovs-vsctl[11617]: ovs|00001|vsctl|INFO|Called as ovs-vsctl --timeout=120 -- --if-exists del-port vhu81f803a2-ac -- add-port br-int vhu81f803a2-ac -- set Interface vhu81f803a2-ac external-ids:iface-id=81f803a2-ac81-4ee8-ba72-93f1e45a546c external-ids:iface-status=active external-ids:attached-mac=fa:16:3e:a8:08:98 external-ids:vm-uuid=67bb2da9-5e5d-48c5-9e98-84fb26bfb362 type=dpdkvhostuserclient options:vhost-server-path=/var/run/openvswitch/vhu81f803a2-ac

IIRC, with dpdkvhostuser interfaces (as opposed to dpdkvhostuserclient), the OVS instance acts as the server. As a result, removing and re-adding the instance results in a loss of connectivity. This doesn't happen with dpdkvhostuserclient because QEMU is the server. As a result, this seems like something we should not be doing.

*However*, there is another issue: we do things this way because of bug #1270973 (and related bug #1268762). This behavior was introduced in https://github.com/openstack/nova/commit/33cc64fb817. I'm not entirely sure that the issue that describes is valid one as it seems like a bug with OVS (otherwise what's the point of the '--may-exist' flag?). However, I need to examine this to figure out what's happening.

As noted in the review [0], the bug that this was working around was fixed in OVS 2.6.0 [1], meaning that commit 33cc64fb817 mentioned above is not only causing issues with some patches but it should also no longer be necessary. IMO, we should likely revert it in it's entirety, which is what [0] is pretty much doing.

[0] https://review.openstack.org/#/c/546588/1
[1] https://github.com/openvswitch/ovs/commit/e21c6643a02c6b446d2fbdfde366ea303b4c2730

The os-vif change https://review.openstack.org/#/c/546588 merged on 2018-03-06.

So, if I understand correctly, we need a os-vif library release and that minimum version included in nova's requirements.txt before we can close this bug for nova.

Reviewed: https://review.openstack.org/550079
Committed: https://git.openstack.org/cgit/openstack/os-vif/commit/?id=3be52b9e650db643827b8b97b28799407f30926f
Submitter: Zuul
Branch: stable/queens

commit 3be52b9e650db643827b8b97b28799407f30926f
Author: Sahid Orentino Ferdjaoui <email address hidden>
Date: Wed Feb 21 14:13:10 2018 +0100

    ovs: do not delete port if already exists

    Change-Id: I0ab28bc38be1f72635afa97c2c4651cd1c2ab336
    Closes-Bug: #1670628
    (cherry picked from commit dadc65c0fae857020f75c8180f159f72cd66c7bd)

This issue was fixed in the openstack/os-vif 1.10.0 release.

This issue was fixed in the openstack/os-vif 1.9.1 release.

Reviewed: https://review.openstack.org/550080
Committed: https://git.openstack.org/cgit/openstack/os-vif/commit/?id=89b0bea3f32260fc1032729e7a75c3250aed8494
Submitter: Zuul
Branch: stable/pike

commit 89b0bea3f32260fc1032729e7a75c3250aed8494
Author: Sahid Orentino Ferdjaoui <email address hidden>
Date: Wed Feb 21 14:13:10 2018 +0100

    ovs: do not delete port if already exists

    Change-Id: I0ab28bc38be1f72635afa97c2c4651cd1c2ab336
    Closes-Bug: #1670628
    (cherry picked from commit dadc65c0fae857020f75c8180f159f72cd66c7bd)
    (cherry picked from commit 3be52b9e650db643827b8b97b28799407f30926f)

This issue was fixed in the openstack/os-vif 1.7.1 release.