Configuring dhcp static ip assignment to kvm host vms

Libvirtd by default uses dnsmasq to provide ip address for kvm host vms automatically when libvirtd daemon is started.

virtual network switch can be provided ip address from dhcp, it uses dnsmasq server.

use the below bash one liner to print all the kvm mac address and respective host name

#virsh list --all | awk '{print $2}' | grep -v Name | xargs -I {} virsh dumpxml {} | grep -i '<mac address' > /tmp/mac && virsh list --all | awk '{print $2}' | grep -v " "| grep -v Name | xargs -n1 > /tmp/hosts && pr -m -t /tmp/mac /tmp/hosts

52:54:00:d8:a0:f4        centosext
52:54:00:2d:07:d3        centosext1
52:54:00:17:1a:99        centosext2
52:54:00:7b:f9:f3        centosext3
52:54:00:df:5f:2f        centosext4
52:54:00:d8:a0:f4        centosext5
52:54:00:82:18:49        chefnode1
52:54:00:8d:10:87        chefnode2
52:54:00:c6:41:eb        chefnode3
52:54:00:7a:73:a0        chefnode4
52:54:00:e1:1b:06        cipher_default

finding the kvm bridge name

#virsh net-list
 Name                 State      Autostart     Persistent
----------------------------------------------------------
 default              active     yes           yes
 vagrant-libvirt      active     no            yes

lets edit the default network used by libvirt.

#virsh net-edit default
<network>
  <name>default</name>
  <uuid>cdaebe20-c72d-4434-932e-58e00de5e837</uuid>
  <forward mode='nat'/>
  <bridge name='virbr0' stp='on' delay='0'/>
  <mac address='52:54:00:d9:5b:b9'/>
  <ip address='192.168.122.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.122.2' end='192.168.122.254'/>
    </dhcp>
  </ip>
</network>

The location of the xml configuration file will be located at /etc/libvirt/qemu/networks/default.xml

To reserve ip address on mac add entries similar to

<network>
  <name>default</name>
  <uuid>cdaebe20-c72d-4434-932e-58e00de5e837</uuid>
  <forward mode='nat'/>
  <bridge name='virbr0' stp='on' delay='0'/>
  <mac address='52:54:00:d9:5b:b9'/>
  <ip address='192.168.122.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.122.2' end='192.168.122.254'/>
      <host mac='52:54:00:d8:a0:f4' name='centosext' ip='192.168.122.11'/>
      <host mac='52:54:00:2d:07:d3' name='centosext1' ip='192.168.122.22'/>
      <host mac='52:54:00:17:1a:99' name='centosext2' ip='192.168.122.33'/>
      <host mac='52:54:00:7b:f9:f3' name='centosext3' ip='192.168.122.44'/>
      <host mac='52:54:00:df:5f:2f' name='centosext4' ip='192.168.122.55'/>
      <host mac='52:54:00:d8:a0:f4' name='centosext5' ip='192.168.122.66'/>
      <host mac='52:54:00:82:18:49' name='chefnode1' ip='192.168.122.77'/>
      <host mac='52:54:00:8d:10:87' name='chefnode2' ip='192.168.122.88'/>
      <host mac='52:54:00:c6:41:eb' name='chefnode3' ip='192.168.122.99'/>
      <host mac='52:54:00:7a:73:a0' name='chefnode4' ip='192.168.122.100'/>
    </dhcp>
  </ip>
</network>

Lets restart the network interface.

# virsh net-destroy default
Network default destroyed

#virsh net-start default
Network default started

# virsh net-info default
Name:           default
UUID:           cdaebe20-c72d-4434-932e-58e00de5e837
Active:         yes
Persistent:     yes
Autostart:      yes
Bridge:         virbr0