virt-manager fails to create virtual network when ipv6 is disabled

[Matt Brown]

Binary package hint: virt-manager

virt-manager fails to create virtual networks (specifically the bridge device) when ipv6 is not present or disabled (in my case with ipv6.disable=1 on the kernel cmdline to work around some silly NFS bugs).

Steps to Reproduce:
1) Start virt-manager
2) Right click on 'localhost', select "details', go to the 'Virtual Networks' tab
3) Select the 'default' network, click on the 'Play/Run' button

Expected Behaviour:

virt manager should create the bridged interface as defined in the default configuration

Actual Behaviour:

An error dialog with the following message pops up and the interface is not created:

Error starting network: cannot disable /proc/sys/net/ipv6/conf/virbr0/accept_ra: No such file or directory

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/host.py", line 401, in start_network
    net.start()
  File "/usr/share/virt-manager/virtManager/network.py", line 97, in start
    self.net.create()
  File "/usr/lib/python2.6/dist-packages/libvirt.py", line 866, in create
    if ret == -1: raise libvirtError ('virNetworkCreate() failed', net=self)
libvirtError: cannot disable /proc/sys/net/ipv6/conf/virbr0/accept_ra: No such file or directory

Because there is no virtual interface, virt-manager refuses to start any VMs.

matt@krypton:~$ lsb_release -rd
Description: Ubuntu 10.10
Release: 10.10

matt@krypton:~$ apt-cache policy virt-manager
virt-manager:
  Installed: 0.8.4-7ubuntu1.1
  Candidate: 0.8.4-7ubuntu1.1
  Version table:
 *** 0.8.4-7ubuntu1.1 0
        500 http://xenon/ubuntu/ maverick-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     0.8.4-7ubuntu1 0
        500 http://xenon/ubuntu/ maverick/main amd64 Packages

[Serge Hallyn (serge-hallyn)]

Thanks for reporting this bug and helping to make Ubuntu better.

This particular bug has been fixed in upstream libvirt, but is not yet fixed in natty. For lucid and maverick, the easiest fix is to use a debdiff like the below. For Natty, we should see about taking a more recent snapshot of libvirt.