libvirt can't add host definitions to DHCP without network restart

[Neil Wilson]

libvirt networks need to be shutdown and restarted to add ranges and/or static mappings to the dhcp definition sections. This breaks service for those VM guests currently running.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: libvirt-bin 0.7.5-5ubuntu27
ProcVersionSignature: Ubuntu 2.6.32-22.33-server 2.6.32.11+drm33.2
Uname: Linux 2.6.32-22-server x86_64
Architecture: amd64
Date: Mon May 24 11:46:07 2010
InstallationMedia: Ubuntu-Server 10.04 LTS "Lucid Lynx" - Release amd64 (20100427)
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: libvirt

[C de-Avillez (hggdh2)]

Thank you for adding in the upstream bug reference. I am marking this Confirmed/Medium.

[Id2ndR (id2ndr)]

Try this that has been working for me when I added a name (in /etc/hosts host's file) to the IP used by the guess: $ sudo kill -HUP `pidof dnsmasq`

Howerver I get a different (related trouble): custom host definition is not honor with my configuration (even after rebooting the host). dnsmasq give a adress from the dhcp range to my VM.
Here is my config /etc/libvirt/qemu/networks/default.xml
<network>
  <name>default</name>
  <bridge name="virbr%d" />
  <forward/>
  <ip address="192.168.122.1" netmask="255.255.255.0">
    <dhcp>
      <range start="192.168.122.100" end="192.168.122.239" />
      <host mac="52:54:00:bf:0f:d0" name="test" ip="192.168.122.10" />
    </dhcp>
  </ip>
</network>

sudo grep 52:54:00:bf:0f:d0 /etc/libvirt/qemu/*.xml
/etc/libvirt/qemu/test.xml: <mac address='52:54:00:bf:0f:d0'/>

Do you have any idea that may explain why this doesn't work ?

[Id2ndR (id2ndr)]

Ok in fact I founded why this was not working. I deleted and recreated my VM but there still was an entry corresponding to the old one in /var/lib/libvirt/dnsmasq/default.hostsfile. So I modified the MAC address and now it is working like a charm (after using HUP signal).

[graemev (graeme-launchpad)]

On the chance that it helps. I observed the following behavior:

in virsh

net-edit default
 ... add and entry (call this version 1)
net-destroy default
net-start default

/var/lib/libvirt/network/default.xml is changed but /var/lib/libvirt/dnsmasq/default.hostfile is NOT

net-edit default
 ... edit the MAC address on an unrelated (junk) entry (call this version 2)
net-destroy default
net-start default

Now /var/lib/libvirt/dnsmasq/default.hostfile is changed , but it reflects the file called version 1 above.

Seems to lag one version behind.

[Serge Hallyn (serge-hallyn)]

This should be fixed upstream since before 14.04, so marking fix released. if you still have this problem please comment so we can re-open.

[dino99 (9d9)]

The redhat has been closed