[libvirt-users] Remove Virtual bridge and DNSMASQ

[Laine Stump]

(in before Eric for this :-) Please don't top-post in responses on this
list (or most other technical lists). Posting your responses in the
context of the previous message makes it much easier for followups that
want to respond to points from several messages at once (and also makes
it easier to understand the discussion by reading just one of those
messages).

On 04/24/2015 11:08 AM, mimicafe at gmail.com wrote:
> HI Michal
>
>
> Thank you for explaining. I have this situation in a number of
> production servers where we would always use static IPs for the host
> and VMs. In such  case we have no requirement for NATed network in the
> future. And we we ever do, we can rely on a DHCP server within the LAN
> to provide IPs to the VMs.
>
> I'll look to remove
> both  libivirt-daemon-driver-network, libvirt-daemon-driver-network
> and dnsmasq.

You can't remove libvirt-daemon-driver-network, as
libvirt-daemon-driver-qemu is dependent on it (for very good reasons).
If you try to do this, you will almost surely end up with a crashing
libvirtd.


>
> Any further thought from your side?


>
> On 24 April 2015 at 13:12, Michal Privoznik <mprivozn at redhat.com
> <mailto:mprivozn at redhat.com>> wrote:
>
>     On 24.04.2015 12 <tel:24.04.2015%2012>:45, mimicafe at gmail.com
>     <mailto:mimicafe at gmail.com> wrote:
>     > I am running KVM virtualization with libvirtd (libvirt) 0.10.2 
>     in bridged
>     > network mode, however I still have the default virtual network
>     > bridge/interfaces and dnsmasq on the host. What I am trying to
>     understand
>     > is whether or not dnsmasq and the virtual network (*virbr0,
>     Vnet0 and Vnet1*)
>     > still play any role. If not, can I remove them?
>

You are mixing together a couple differnet (but related) things. virbr0
is a bridge device created for libvirt's "default" virtual network, and
the dnsmasq instance that is running is also run by libvirt for that
network. However, the vnet0 and vnet1 devices are tap devices; one of
these is created for each domain interface, whether you use libvirt's
network or you connect to a host bridge that you've configured yourself
- you can't eliminate those devices.

>
>     Yes, you can safely remove libvirt-daemon-config-network package. It
>     should disable the default network.
>

Actually that won't disable any already-installed default network.
You'll need to do this:

    virsh net-destroy default
    virsh net-undefine default

Once you've done this, the virbr0 device will no longer appear, and
dnsmasq will not be run (although the binary will still be present on
the disk).

>     However, dropping dnsmasq is a bit
>     harder, since libivirt-daemon-driver-network depends on it. We can't
>     know whether you will not someday like a NATed network with a DHCP
>     server, even though now you don't. However,
>     libvirt-daemon-driver-network takes care about all the network types
>     known to libvirt, so you can't really drop it (unless forcibly
>     removing
>     the package and let the libvirt just deal with it, which I'd
>     discourage
>     you from doing anyway).
>

That's not going to work. There are things in the network driver other
than just libvirt's virtual networks, and qemu isn't setup to deal with
the network driver not being present.


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listman.redhat.com/archives/libvirt-users/attachments/20150424/a451eabc/attachment.htm>