[virt-tools-list] [virt-manager] How to have regular bridges in the network source list

[Pavel Hrdina]

On Sat, Apr 15, 2017 at 07:35:53PM +0200, Marc Haber wrote:
> Hi,
> 
> back in 2010, this list had a short thread about regular bridges not
> showing up in the network source list in virt-manager. The gist of the
> thread was "use virt-manager 0.8.4 and you'll see bridges".
> 
> Now, seven years later, I have virt-manager 1.4.0 on the admin machine
> (Debian unstable) and libvirt 2.9 on the server (Debian stable), and I
> still have to select "Specify shared device name" in the network source
> list and enter my bridge name myself, while physical interfaces and
> macvlans show up automagically.
> 
> While I do understand that macvlan is the hot stuff at the moment and
> people want us to use those, there is a gazillion use cases of classical
> bridges, for example when the guest needs to talk to the host or when
> the party providing network access to the host routes additional IP
> addresses to the host IP instead of arping for them on the physical
> network.
> 
> Is there still a technical reason why virt-manager doesn't show regular
> bridge interfaces in the interface dropdown? Can I help with local
> configuration or am I stil stuck with manually entering "br0"?

Hi, it depends how the bridge is configured.  If you create a bridge via
virt-manager/libvirt you will be able to see it in virt-manager.  It should
also appear in virt-manager if you configure the bridge via
/etc/network/interfaces.  However, if you configure the bridge using brctl
util you will not see it in virt-manager.

Some background to this topic, for remote connection virt-manager displays
only what it can get via libvirt on the remote host.  So if you run
"virsh iface-list" on the remote host and there is no "br0", you would not
be able to see it in virt-manager as well.

The reason why libvirt doesn't consider showing bridges defined via brctl
is because they are not persistent and they are probably configured
manually by hand or by some shell script or any other tool which is out
of libvirt scope.

I would recommend to check how the bridge is configured, for example this
configuration works for me:

    auto br0
    iface br0 inet dhcp
      bridge_ports eth0

Pavel

> 
> Greetings
> Marc
> 
> -- 
> -----------------------------------------------------------------------------
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> 
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