nova network on multihost does not delete bridges during deletion of networks

[Marian Horban]

The teardown_unused_network_gateway parameter=true parameters is used by VlanManager in nova-network to remove bridge and vlan interfaces when the network is deleted. With CentOS 6.5 these interfaces are not delete bridge. In the log there are right lines:

2014-12-12 14:50:33.957 4606 DEBUG nova.openstack.common.processutils [req-8f33392b-db62-462c-a6b5-8008b7ea5412 ] Running cmd (subprocess): sudo nova-rootwrap /etc/nova/rootwrap.conf ip link delete br204 execute /usr/lib/python2.6/site-packages/nova/openstack/common/processutils.py:154
2014-12-12 14:50:32.881 4606 DEBUG nova.network.linux_net [req-3ec984c3-fbab-45c2-9002-057a6e3306a2 None] Net device removed: 'br204' delete_net_dev /usr/lib/python2.6/site-packages/nova/network/linux_net.py:1361

But actually the bridge interface still exists:

154: br204: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN
    link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
    inet 10.42.1.3/24 brd 10.42.1.255 scope global br204
    inet 10.42.2.3/24 brd 10.42.2.255 scope global br204
    inet6 fe80::109d:f0ff:feb2:9d64/64 scope link
       valid_lft forever preferred_lft forever

The command fails in the shell:

[root@node-77 ~]# ip link delete br204
RTNETLINK answers: Operation not supported
[root@node-77 ~]# echo $?
2

This bug is not a nova-network issue, but rather a problem with linux kernel: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=680094 , but can be fixed in nova-network by replacing "ip link delete" command with "ip link set <dev> down && brctl delbr <dev>" commands

[Marian Horban (mhorban)]

Test script for reproducing bug in attachment.
Before using script env variables $COMPUTE_HOST(IP address of compute node) and $COMPUTE_USER(OS user of compute node) must be exported.

[Jay Pipes (jaypipes)]

Setting to High because this leaves bridges around after deletion of instances...

[Davanum Srinivas (DIMS) (dims-v)]

Looks like the review for this bug is:
https://review.openstack.org/#/c/157471/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/157471
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=1c1a7974ff2acde5d35a1f7a6d9767cd38869752
Submitter: Jenkins
Branch: master

commit 1c1a7974ff2acde5d35a1f7a6d9767cd38869752
Author: Marian Horban <email address hidden>
Date: Thu Feb 19 13:06:11 2015 -0500

    Ensure bridge deleted with brctl delbr

    A linux kernel bug (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=680094)
    causes `ip link delete` to fail to remove a bridge created
    with brctl. Using `brctl delbr` ensures that the bridge is
    properly destroyed.

    Closes-Bug: #1424756
    Change-Id: I18241f5fa989b177ea54e1347827cee6b629b253