Usage of KVM

• Install KVM Ubuntu 16.04, CentOS 7
• Bridge interface Ubuntu 16.04, CentOS 7
• Install bind Ubuntu 16.04, CentOS 7
• Install dhcp server Ubuntu 16.04, CentOS 7

• Generate /etc/resolv.conf by DHCP server
• GRUB2 and Linux with serial console Ubuntu 16.04, CentOS 7, ArchLinux, Debian 8, Fedora 24
• Install openssh-server
• Install XRDP

Cloning is good for trying Linux. You can run auto scripts with using virt-clone.

$ sudo virt-clone -o ubuntu-16.04 -n ubuntu-16.04-clone \
-f /var/lib/libvirt/images/ubuntu-16.04-clone.img

Remove virtual machine with virsh undefine and rm.

$ virsh undefine ubuntu-16.04-clone
$ rm ubuntu-16.04-clone.img # /var/lib/libvirt/images/ubuntu-16.04-clone.img

If prepared serial console on virtual machine, you can operate virtual machine via console with virsh console.

$ virsh console <vmname>

The virsh can be run via SSH.

$ ssh -q -t <server> virsh console <vmanme>

Use VGA because VNC server cannot use QXL as display.

Use VNC server.

You can find display number of VNC with virsh vncdisplay.

$ sudo virsh vncdisplay <vmname>
:1

$

Running below scripts on OSX will connect to VNC server. Please change SERVER to yours.

#!/bin/sh

SERVER=acer.hiroom2.com
VIRSH="ssh -q -t ${SERVER} sudo virsh"

display=`${VIRSH} vncdisplay ${1} | sed -e 's/://g' -e 's/[ \r\n]//g'`
port=`expr 5900 + ${display}`
open vnc://${SERVER}:${port}

When cloning virtual machine with virt-clone, VNC password is not taken over to new virtual machine. You need to append passwd='password' to virtual machines XML file. Please change 'password' to yours.

$ sudo virt-clone -o <src_vmname> -n <dst_vmname> -f <imgname>
$ sudo sed -i "s/keymap='ja'/keymap='ja' passwd='password'/g" \
/etc/libvirt/qemu/<dst_vmname>.xml
$ sudo systemctl restart libvirtd

virsh list provides list of virtual machine. –name option is useful for scripts.

$ sudo virsh list --name            # Print active domain
$ sudo virsh list --name --inactive # Print inactive domain
$ sudo virsh list --name --all      # Print all domain

For example, all virtual machines are suspended as below.

$ for vm in `sudo virsh list --name --all`; do
  sleep 30;                # wait VM
  sudo virsh suspend ${vm} # Suspend VM
done

Extract MAC address from virsh dumpxml.

#!/bin/sh

VIRSH="sudo virsh"

mac=`${VIRSH} dumpxml ${1} | grep "mac address"`
mac=`echo ${mac} | sed s/\ *\<mac\ address=\'//g | sed s:\'/\>::g`
echo "${mac}"

You might need to reboot host machine for security update or system backup. The libvirt-guests service provides suspend/resume virtual machine when rebooting host machine.

$ sudo systemctl enable libvirt-guests
$ sudo systemctl restart libvirt-guests

In case of CentOS 7 is as below.

$ diff -uprN /etc/sysconfig/libvirt-guests{.org,}
--- /etc/sysconfig/libvirt-guests.org   2016-07-12 21:39:20.801212101 +0900
+++ /etc/sysconfig/libvirt-guests       2016-07-12 21:39:45.574005615 +0900
@@ -9,6 +9,7 @@
 #           guests marked as autostart will still be automatically started by
 #           libvirtd
 #ON_BOOT=start
+ON_BOOT=start

 # Number of seconds to wait between each guest start. Set to 0 to allow
 # parallel startup.
@@ -23,6 +24,7 @@
 #             ON_SHUTDOWN=shutdown, you must also set SHUTDOWN_TIMEOUT to a
 #             value suitable for your guests.
 #ON_SHUTDOWN=suspend
+ON_SHUTDOWN=suspend

 # If set to non-zero, shutdown will suspend guests concurrently. Number of
 # guests on shutdown at any time will not exceed number set in this variable.

In case of Ubuntu 16.04 is as below.

$ diff -uprN /etc/default/libvirt-guests{.org,}
--- /etc/default/libvirt-guests.org     2016-07-12 13:23:54.793891291 +0900
+++ /etc/default/libvirt-guests 2016-07-12 13:27:00.748614276 +0900
@@ -9,6 +9,7 @@
 #           guests marked as autostart will still be automatically started by
 #           libvirtd
 #ON_BOOT=ignore
+ON_BOOT=start

 # Number of seconds to wait between each guest start. Set to 0 to allow
 # parallel startup.
@@ -23,6 +24,7 @@
 #             ON_SHUTDOWN=shutdown, you must also set SHUTDOWN_TIMEOUT to a
 #             value suitable for your guests.
 #ON_SHUTDOWN=shutdown
+ON_SHUTDOWN=suspend

 # If set to non-zero, shutdown will suspend guests concurrently. Number of
 # guests on shutdown at any time will not exceed number set in this variable.