Use virt-install to fully automate the install for Devuan with preseed

I recently discovered how to use a Debian preseed file while building a VM in kvm. After hand-crafting my Devuan preseed file, here it is in all my customized and I’m sure duplicate-filled and bogus-answer-encrusted glory.

How I use this

I define a variable, and plug it into the important parts.

vm=d2-04a ; time sudo virt-install -n "${vm}" --memory 2048 \
   --vcpus=1 --os-variant=debiantesting -v \
   --disk path=/var/lib/libvirt/images/"${vm}".qcow2,size=20 \
   -l /mnt/public/Support/SetupsBig/Linux/devuan_ascii_2.0.0-beta_amd64_DVD.iso \
   --initrd-inject=/mnt/public/Support/Platforms/devuan/preseed/preseed.cfg \
   --extra-args "hostname=${vm} NOTIFYEMAIL=bgstack15@gmail.com interface=auto" \
   --debug --network type=bridge,source=br0 --noautoconsole

Some thoughts

For some reason I was unable to get the preseed to work with the non-beta Ascii iso. When I started the preseed vm activity, I already had the beta disc so I was using it first before I downloaded the release disc, which didn’t even work. So I reverted to the beta disc. Please share any results, working or otherwise, you have when trying this with the release disc.
I do some tricky stuff in here with grub and the ceres release. Apparently consolekit messes with some of the files grub wants to lay down in /boot (having to do with locales), so I had to create this complex solution. I don’t even care that it’s “grub-legacy.” It seems a little simpler for a simpler time, and also works, so why bother doing anything different?

The preseed file

# File: /mnt/public/Support/Platforms/devuan/devuan-preseed1.txt
# Locations:
#    /mnt/public/Support/Platforms/devuan/devuan-preseed1.txt
# Author: bgstack15
# Startdate: 2019-06-25
# Title: Kickstart for CentOS 7 for ipa.smith122.com
# Purpose: To provide an easy installation for VMs and other systems in the Mersey network
# History:
#    2017-06 I learned how to use kickstart files for the RHCSA EX-200 exam
#    2017-08-08 Added notifyemail to --extra-args
#    2017-10-29 major revision to use local repository
#    2019-06-25 fork from centos7-ks.cfg
# Usage with virt-install:
#    vm=d2-04a ; time sudo virt-install -n "${vm}" --memory 2048 --vcpus=1 --os-variant=debiantesting -v --disk path=/var/lib/libvirt/images/"${vm}".qcow2,size=20 -l /mnt/public/Support/SetupsBig/Linux/devuan_ascii_2.0.0-beta_amd64_DVD.iso --initrd-inject=/mnt/public/Support/Platforms/devuan/preseed/preseed.cfg --extra-args "hostname=${vm} NOTIFYEMAIL=bgstack15@gmail.com interface=auto" --debug --network type=bridge,source=br0 --noautoconsole
#    vm=d2-04a; sudo virsh destroy "${vm}"; sudo virsh undefine --remove-all-storage "${vm}";
# Reference:
#    https://sysadmin.compxtreme.ro/automatically-set-the-hostname-during-kickstart-installation/
#    /mnt/public/Support/Platforms/CentOS7/install-vm.txt
#    https://serverfault.com/questions/481244/preseed-command-string-fail-with-newline-character-using-virt-install-initrd-inj
#    https://www.debian.org/releases/stable/i386/apbs01.html.en
#    https://github.com/jameswthorne/preseeds/blob/master/debian-7-wheezy-unattended.seed
#    syntax for --location https://www.queryxchange.com/q/1_908324/virt-install-preseed-not-working/
#    example preseed https://www.debian.org/releases/stable/example-preseed.txt
#    skip next dvd question https://unix.stackexchange.com/questions/409212/preseed-directive-to-skip-another-cd-dvd-scanning
#    grub problem caused by consolekit:amd64 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=915947#10
#    https://stackoverflow.com/questions/39861614/how-to-fully-automate-unattended-virt-install
#    https://www.debian.org/releases/stable/i386/apbs03.html.en
#    https://dev1galaxy.org/viewtopic.php?id=1853
#    https://www.cyberciti.biz/faq/howto-setup-serial-console-on-debian-linux/
# Improve:
#    discover how to send email, using postfix or sendmail. Don't care which, but exclude exim4.
#    echo "$( hostname ) has IP $( ip -4 -o a s eth0 | awk '{print $4}' | sed -r -e 's/\/.*$//' )" | 
#    add the kernel lines: console=ttyS0 console=tty1. Get this to work; tried manually but perhaps devuan doesn't use console the same way?

d-i debian-installer/country string US
d-i debian-installer/keymap select us
d-i debian-installer/language string en
d-i debian-installer/locale string en_US
d-i localechooser/supported-locales string en_US.UTF-8

d-i keyboard-configuration/layoutcode string us
d-i keyboard-configuration/variantcode string
d-i keyboard-configuration/xkb-keymap select us

d-i netcfg/disable_autoconfig boolean false
d-i netcfg/get_domain string ipa.smith122.com
d-i netcfg/wireless_wep string
# disable asking for non-free firmware, because this is a vm and has none
d-i hw-detect/load_firmware boolean false

#d-i apt-setup/enable-source-repositories boolean false
# ORIGINAL d-i apt-setup/services-select multiselect security updates, release updates, backported software
d-i apt-setup/contrib boolean true
d-i apt-setup/disable-cdrom-entries boolean true
d-i apt-setup/non-free boolean true
d-i apt-setup/use_mirror boolean true
d-i mirror/country string manual
d-i mirror/http/directory string /devuan
d-i mirror/http/hostname string deb.devuan.org
d-i mirror/http/proxy string
d-i mirror/protocol string http
d-i mirror/suite string testing

d-i apt-setup/cdrom/set-failed boolean false
d-i apt-setup/cdrom/set-first boolean false
d-i apt-setup/cdrom/set-next boolean false

# my repos and ceres
d-i apt-setup/local0/comment string smith122deb
d-i apt-setup/local0/key string http://albion320.no-ip.biz/smith122/repo/deb/smith122deb.gpg
d-i apt-setup/local0/repository string http://albion320.no-ip.biz/smith122/repo/deb/ /
d-i apt-setup/local1/comment string devuan-deb
d-i apt-setup/local1/key string http://albion320.no-ip.biz/smith122/repo/deb/smith122deb.gpg
d-i apt-setup/local1/repository string http://albion320.no-ip.biz/smith122/repo/devuan-deb/ /
d-i apt-setup/local2/comment string ceres
d-i apt-setup/local2/key string https://pkgmaster.devuan.org/merged/dists/ceres/Release.gpg
d-i apt-setup/local2/repository string http://pkgmaster.devuan.org/merged ceres main contrib non-free
# if for some reason I really need to turn off the gpg key check:
#d-i debian-installer/allow_unauthenticated boolean false

tasksel tasksel/first multiselect standard, ssh-server

# adapted from /mnt/public/Support/Platforms/devuan/devuan.txt, main fluxbox desktop, but for a vm
# no xscreensaver, for a vm.
d-i pkgsel/include string \
   alsamixergui alttab apt-transport-https bgconf bgscripts bgscripts-core \
   cifs-utils curl fluxbox freeipa-client git grub lightdm lightdm-gtk-greeter \
   mlocate net-tools nfs-common ntpdate oddjob-mkhomedir=0.1-1 openssh-server \
   p7zip palemoon palemoon-ublock-origin parted qemu-guest-agent rsync scite \
   screen spice-vdagent strace sudo tcpdump vim vlc volumeicon-alsa waterfox \
   xfce4-terminal xfe xserver-xorg-video-qxl

d-i pkgsel/upgrade select none

popularity-contest popularity-contest/participate boolean true

d-i clock-setup/ntp boolean true
d-i clock-setup/ntp-server string dns1.ipa.smith122.com
d-i time/zone string America/New_York

# skip grub during main part, because we will do it in late_command
d-i grub-installer/skip boolean true
# these next 2 are experimental
d-i grub-installer/skip-again boolean true
d-i grub-installer/skip-confirm boolean true
d-i grub-installer/confirm_skip boolean true
d-i nobootloader/confirmation_common boolean true

d-i lilo-installer/skip boolean true
#d-i grub-installer/with_other_os boolean true
#d-i grub-installer/only_debian boolean true
#d-i grub-installer/grub2_instead_of_grub_legacy boolean true
#d-i grub-installer/bootdev string /dev/vda
#d-i grub-installer/choose_bootdev select /dev/vda
#grub-installer grub-installer/force-efi-extra-removable boolean false

d-i passwd/root-password password f0rg3tkickstart&
d-i passwd/root-password-again password f0rg3tkickstart&

d-i partman-auto/choose_recipe select home
d-i partman-auto-crypto/erase_disks boolean false
d-i partman-auto/disk string /dev/vda
d-i partman-auto/init_automatically_partition select biggest_free
d-i partman-auto/method string lvm
d-i partman/choose_label string gpt
d-i partman/choose_partition select finish
d-i partman/confirm boolean true
d-i partman/confirm_nooverwrite boolean true
d-i partman/confirm_write_new_label boolean true
d-i partman/default_label string gpt
#d-i partman-lvm/confirm boolean true
d-i partman-lvm/confirm_nooverwrite boolean true
d-i partman-md/confirm_nooverwrite boolean true
#d-i partman/mount_style select uuid
d-i partman-partitioning/confirm_write_new_label boolean true

# Uncomment this to add multiarch configuration for i386
#d-i apt-setup/multiarch string i386

d-i passwd/make-user boolean true
d-i passwd/user-fullname string bgstack15
d-i passwd/username string bgstack15
d-i passwd/user-password-crypted password $6$85aKM2DkiD5g9r3D$zkbcVES1Bzu.b5dBJxklSggEJzswZBlVAyc9LUUIzMA2OLRH2PD2ZWE9Q40Wtw/3OOxDM2nF031hfD4s5LGuG1
d-i passwd/user-default-groups string audio cdrom video

d-i finish-install/reboot_in_progress note
d-i cdrom-detect/eject boolean true

# additional application stuff just in case it works and is useful
# LDAP server URI:
d-i shared/ldapns/ldap-server	string	ldapi:///ipa.smith122.com

d-i openssh-server/password-authentication	boolean	true
d-i openssh-server/permit-root-login	boolean	false

# Remove consolekit from ceres, which disrupts /boot/grub/local/*mo files, that grub-install wants.
d-i preseed/late_command string in-target apt-get purge -q -y -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" consolekit exim4\* ; \
   apt-get install -q -y -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" postfix ; \
   in-target grub-install /dev/vda ; in-target update-grub ; \
   in-target wget http://albion320.no-ip.biz/smith122/certs/ca-ipa.smith122.com.crt -O /usr/local/share/ca-certificates/ca-ipa.smith122.com.crt && update-ca-certificates || : ; \
   in-target su bgstack15 -c "sudo /usr/bin/bgconf.py" 1>/root/clone.log 2>&1 ; \
   in-target sed -i -r -e '/^kernel/s/(\s*console=.{1,7}[0-9])*\s*$/ console=tty0 console=ttyS0/;' /boot/grub/menu.lst ; \
   in-target sed -i -r -e '$aT0:23:respawn:/sbin/getty -L ttyS0 9600 vt100' /etc/inittab

Use virt-install to fully automate the install for CentOS/Fedora with kickstart

Here is my kickstart file for CentOS 7. I deploy VMs into my kvm environment with a oneliner, using this kickstart file.

How I use this

I define a variable, and plug it into the important parts.

vm=c7-04a ; time sudo virt-install -n "${vm}" --memory 2048 \
   --vcpus=1 --os-variant=centos7.0 --accelerate -v \
   --disk path=/var/lib/libvirt/images/"${vm}".qcow2,size=20 \
   -l /mnt/public/Support/SetupsBig/Linux/CentOS-7-x86_64-Minimal-1810.iso \
   --initrd-inject=/mnt/public/Support/Platforms/CentOS7/centos7-ks.cfg \
   --extra-args "ks=file:/centos7-ks.cfg SERVERNAME=${vm} NOTIFYEMAIL=bgstack15@gmail.com" \
   --debug --network type=bridge,source=br0 --noautoconsole

Some thoughts

I had to download the 1810 release of the iso, because there was something wrong with the repos or perhaps files in the previous isos, with how they interacted with either the virtual environment or the network or something. But the CentOS-7-x86_64-minimal-1810.iso was important.
I found the SERVERNAME trick on the Internet. You can iterate over /proc/cmdline and react to values you find there, in the %pre or %post scripts.
You will see that I use my own local repositories for the regular CentOS repos, and I add my own internal one (smith122/repo/rpm). Obviously you should find a suitable set of repos for your own.
You will also see that I attempt to download my CA certificates at various points. I’m pretty sure the %pre effort fails, because the system is not on the network yet.

Dependencies

The kickstart file

# File: /mnt/public/Support/Platforms/CentOS7/centos7-ks.cfg
# Locations:
#    /mnt/public/Support/Platforms/CentOS7/centos7-ks.cfg
# Author: bgstack15
# Startdate: 2017-06-02
# Title: Kickstart for CentOS 7 for ipa.smith122.com
# Purpose: To provide an easy installation for VMs and other systems in the Mersey network
# History:
#    2017-06 I learned how to use kickstart files for the RHCSA EX-200 exam
#    2017-08-08 Added notifyemail to --extra-args
#    2017-10-29 major revision to use local repository
#
#
#
#
# Usage with virt-install:
#    vm=c7-04a ; time sudo virt-install -n "${vm}" --memory 2048 --vcpus=1 --os-variant=centos7.0 --accelerate -v --disk path=/var/lib/libvirt/images/"${vm}".qcow2,size=20 -l /mnt/public/Support/SetupsBig/Linux/CentOS-7-x86_64-Minimal-1810.iso --initrd-inject=/mnt/public/Support/Platforms/CentOS7/centos7-ks.cfg --extra-args "ks=file:/centos7-ks.cfg SERVERNAME=${vm} NOTIFYEMAIL=bgstack15@gmail.com" --debug --network type=bridge,source=br0 --noautoconsole
#    vm=c7-04a; sudo virsh destroy "${vm}"; sudo virsh undefine --remove-all-storage "${vm}";
# Reference:
#    https://sysadmin.compxtreme.ro/automatically-set-the-hostname-during-kickstart-installation/
#    /mnt/public/Support/Platforms/CentOS7/install-vm.txt

#platform=x86, AMD64, or Intel EM64T
#version=DEVEL
# Install OS instead of upgrade
install
# Keyboard layouts
keyboard 'us'
# Root password
rootpw --plaintext SOMETHINGSTRONGHERE
# my user
user --groups=wheel --name=bgstack15-local --password=$6$.gh0u7vg2HDPJPX/$g4Y1l.q76fs7i0UK8t6h83bDIo2YnGGj/1DGeUzzbMTd0pBh4of6jNYWxxws/937sUiPgETqPsYFI5XNrkAle. --iscrypted --gecos="bgstack15-local"

# System language
lang en_US.UTF-8
# Firewall configuration
firewall --enabled --ssh
# Reboot after installation
reboot
# Network information
#attempting to put it in the included ks file that accepts hostname from the virsh command.
#network  --bootproto=dhcp --device=eth0 --ipv6=auto --activate
%include /tmp/network.ks
# System timezone
timezone America/New_York --utc
# System authorization information
auth  --useshadow  --passalgo=sha512
# Use network installation instead of CDROM installation media
url --url="http://www.ipa.smith122.com/mirror/centos/7/os/x86_64/"

# Use text mode install
text
# SELinux configuration
selinux --enforcing
# Do not configure the X Window System
skipx

# Use all local repositories
# Online repos
repo --name=smith122rpm --baseurl=https://www.ipa.smith122.com/smith122/repo/rpm/
repo --name=base --baseurl=https://www.ipa.smith122.com/mirror/centos/$releasever/os/$basearch/
repo --name=updates --baseurl=https://www.ipa.smith122.com/mirror/centos/$releasever/updates/$basearch/
repo --name=extras --baseurl=https://www.ipa.smith122.com/mirror/centos/$releasever/extras/$basearch/
repo --name=epel --baseurl=https://www.ipa.smith122.com/mirror/fedora/epel/$releasever/$basearch

# Offline repos
#
#
#
#
#

firstboot --disabled

# System bootloader configuration
bootloader --location=mbr
# Partition clearing information
clearpart --all --initlabel
# Disk partitioning information
autopart --type=lvm

%pre
echo "network  --bootproto=dhcp --device=eth0 --ipv6=auto --activate --hostname renameme.ipa.smith122.com" > /tmp/network.ks
for x in $( cat /proc/cmdline );
do
   case $x in
      SERVERNAME*)
         eval $x
         echo "network  --bootproto=dhcp --device=eth0 --ipv6=auto --activate --hostname ${SERVERNAME}.ipa.smith122.com" > /tmp/network.ks
         ;;
      NOTIFYEMAIL*)
         eval $x
         echo "${NOTIFYEMAIL}" > /mnt/sysroot/root/notifyemail.txt
         ;;
   esac
done
cp -p /run/install/repo/ca-ipa.smith122.com.crt /etc/pki/ca-trust/source/anchors/ 2>/dev/null || :
wget http://www.ipa.smith122.com/smith122/certs/ca-ipa.smith122.com.crt -O /etc/pki/ca-trust/source/anchors/ca-ipa.smith122-wget.com.crt || :
update-ca-trust || :
%end

%post
(
   # Set temporary hostname
   #hostnamectl set-hostname renameme.ipa.smith122.com;

   # Get local mirror root ca certificate
   wget http://www.ipa.smith122.com/smith122/certs/ca-ipa.smith122.com.crt -O /etc/pki/ca-trust/source/anchors/ca-ipa.smith122.com.crt && update-ca-trust

   # Get local mirror repositories
   wget https://www.ipa.smith122.com/smith122/repo/rpm/smith122rpm.repo -O /etc/yum.repos.d/smith122rpm.repo;
   wget http://www.ipa.smith122.com/smith122/repo/rpm/smith122rpm.mirrorlist -O /etc/yum.repos.d/smith122rpm.mirrorlist
   distro=centos7 ; wget https://www.ipa.smith122.com/smith122/repo/mirror/smith122-bundle-${distro}.repo -O /etc/yum.repos.d/smith122-bundle-${distro}.repo && grep -oP "(? /boot/grub2/grub.cfg

   # postfix is already started by default on centos7
   # Send IP address to myself
   thisip="$( ifconfig 2>/dev/null | awk '/Bcast|broadcast/{print $2}' | tr -cd '[^0-9\.\n]' | head -n1 )"
   {
      echo "${SERVER} has IP ${thisip}."
      echo "system finished kickstart at $( date "+%Y-%m-%d %T" )";
   } | /usr/share/bgscripts/send.sh -f "root@$( hostname --fqdn )" \
      -h -s "${SERVER} is ${thisip}" $( cat /root/notifyemail.txt 2>/dev/null )

   # No changes to graphical boot
   #

   # fix the mkhomedir problem
   systemctl enable oddjobd.service && systemctl start oddjobd.service

   # Personal customizations
   mkdir -p /mnt/bgstack15 /mnt/public
   su bgstack15-local -c "sudo /usr/share/bgconf/bgconf.py"

) >> /root/install.log 2>&1
%end

%packages
@core
@^minimal
autossh
bc
bgconf
bgscripts-core
bind-utils
cifs-utils
cryptsetup
dosfstools
epel-release
expect
firewalld
git
iotop
ipa-client
-iwl*-firmware
mailx
man
mlocate
net-tools
nfs-utils
ntp
p7zip
parted
policycoreutils-python
rpm-build
rsync
screen
strace
sysstat
tcpdump
telnet
vim
wget
yum-utils
%end

Access vm in libvirt/qemu/kvm on serial console from hypervisor

You can access the serial port console of a virtual machine running in qemu, if you have configured the guest kernel correctly.

Configure the guest

# add serial console
sed -i -r -e '/^GRUB_CMDLINE_LINUX=/{s/(\s*)\"$/ console=ttyS0 console=tty1\"/;}' /etc/default/grub
grub2-mkconfig > /boot/grub2/grub.cfg

I have these steps in my kickstart %post scriptlet, so all my VMs get this setting. These steps modify grub to tell the kernel to open a listening console on the first serial console (ttyS0) and also the regular virtual terminal tty1. It is important to denote both, so the spice client sees the tty1, and that virsh on the command line can get to the serial console.

Accessing the guest from the hypervisor

sudo virsh console $GUESTNAME

Once the guest OS has booted, just run this command and you’re connected to the serial console. You have to log in like a true console session, and then you’re in!

Multiple monitors on Windows guest in KVM

Introduction

It is easy to set up a virtual machine with the virt-manager GUI.

To add a second monitor (or more) is also pretty easy, once you know how to do it. However, to view a second monitor simultaneously with the first, you will need to use the tool remote-viewer.

In virt-manager, select “Show virtual hardware details.”
Screenshot of virt-manager open to a virtual machine, "Show virtual hardware details" page.
Add a new video card. A basic QXL type should be sufficient.

It is possible to connect to the guest’s displays over the network, if you configure it to be possible. For example, you use your desktop Virtual Machine Manager to connect to a server’s libvirt via a connection string like qemu+ssh://root@vm1.ipa.example.com/system.

On that virtual machine’s “Display spice” virtual hardware, modify the address tag to “All interfaces.” Also note the the port number given to this guest. In my screenshot you can see mine is port 5907.
Screenshot showing vm settings for display spice

You will want to open up the firewall on the vm host. I suggest just using the vdsm definition, which is for the oVirt project and includes TCP ports 5900-6923.

sudo firewall-cmd --permanent --add-service=vdsm; sudo firewall-cmd --reload

You will need to shut down (not reboot) the guest if it is running at the time, for it to be able to use the new virtual hardware or pretty much any new setting.

Once the virtual machine is running again, use “Remote Viewer” in the GUI, or run from the command line.

remote-viewer spice://vm1.ipa.example.com:5907

Improvements

Learn how to do this in the cli, including maybe at the virt-install statement. Or at least how to retro-fit an existing domain.

References

  1. search “kvm spice guest windows multiple monitors”
  2. Shamelessly ripped off from https://solus-project.com/forums/viewtopic.php?f=11&t=8663
  3. spice guest tools https://www.spice-space.org/download.html

Create, attach, detach disk to vm in kvm on command line

In kvm, let’s say you want to create a new disk and attach it to a virtual machine. You could use Virtual Machine Manager. But for the command line, here is a quick way how to do it.

Create a disk

Create a qcow2 disk that is fully allocated. When I tried with disks that were not fully allocated, the vm would only see the 200K or so and would not let me write a partition table large enough to do anything.

time qemu-img create -f qcow2 /var/lib/libvirt/images/vmname-vdb.qcow2 22000M -o preallocation=full

Attach a disk

You can omit the flags as needed, if you don’t want to update the virtual machine’s definition, or –config. And some of these are probably redundant, but they did not throw errors for me and I wanted the change to be immediate and persistent upon vm reboot, so I leave them all in.

virsh attach-disk --domain vmname /var/lib/libvirt/images/vmname-vdb.qcow2 --target vdb --persistent --config --live

Detach a disk

Same thing as the attaching, only you don’t include the –target flag.

virsh detach-disk --domain vmname /var/lib/libvirt/images/vmname-vdb.qcow2 --persistent --config --live

References

Weblinks

Man pages

  1. qemu-img

Fix Korora xfce spice display pausing

For the Fedora spin Korora with the xfce desktop running in a kvm virtual machine, the display might pause for 2 seconds every so often. The system is running, but sometimes the display just freezes.

To fix this issue, run the xfce “Window Manager Tweaks.” On the “Compositor tab” uncheck “Synchronize drawing to the vertical blank.”

Thanks to Jim at the Korora Project for this one!

Mount an lvm logical volume from a qcow2 file

Mounting qcow2 files to host filesystem

Converting to raw and mounting

kpartx does not work very well with qcow2 files. You can convert the qcow2 file to a raw file:

oldfile=file.qcow2
newfile=file.raw
qemu-img convert "${oldfile}" "${newfile}"

You can now find the partitions and map them:

kpartx -av "${newfile}"
mount /dev/loop2p2 /mnt/foo

Modifying a virtual machine to use the new image file

You can modify a virtual machine definition to use this new file:

virsh dumpxml ${domain} > domain.xml
vi domain.xml # Lines “source file=/path/file.raw” and “driver name=qemu type=raw"
virsh create domain.xml

Mounting lvm logical volumes from the image file

Update lvm with the currently attached disks.

pvscan; lvscan; lvdisplay

Now you can mount /dev/mapper/cl_centos7–02a_root to a mount point.

References

Weblinks

  1. Converting qcow2 file to raw to make it work with kpartx https://www.certdepot.net/rhel7-access-virtual-machines-console/#comment-41448
  2. An alternate way to mount a qcow2 file http://ask.xmodulo.com/mount-qcow2-disk-image-linux.html

Man pages

  1. virsh

Virsh get total cpu allocations

tl;dr

virsh list | awk '{print $1}' | grep -oIE "[0-9]*" | while read word; do virsh dominfo ${word} | grep "CPU.s"; done | awk 'BEGIN {a=0;} {a=a+$2;} END {print a;}'

The explanation

If you want to get the total allocation of vCPUs to all the guests on a kvm host, you can use this one-liner.
virsh list gets the list of running domains (virtual machines).
The awk and grep get only the domain id numbers (could do it by domain name if you wish).
virsh dominfo gets the cpu allocation for each listed domain, by iterating over the list.
The final awk statements counts the numbers.

Get total physical CPUs available

virsh nodeinfo
CPU model:           x86_64
CPU(s):              24
CPU frequency:       1899 MHz
CPU socket(s):       1
Core(s) per socket:  6
Thread(s) per core:  2
NUMA cell(s):        2
Memory size:         198310648 KiB

Installing Korora 25 xfce in qemu/kvm

Overview

I wanted to install a Linux virtual machine on my Linux laptop. Already installed was virtual machine manager. For the time being, my host OS is Fedora 25 KDE and what I wanted to run in the vm is Korora 25 xfce. All this because I don’t know how to have two different versions of Teamviewer run at the same time.

Process

I downloaded the K25 xfce iso and then started the “Create a new virtual machine” wizard. The process was simple enough (minus scraping out enough disk space on my host). I ran into an issue with interacting with the virtual machine, though. During the install, I had to switch my display to VNC server type.

And even then, my mouse location was not aligned the cursor during the entire process. It’s a good thing Anaconda works with keyboard input! I was actually quite impressed because I’ve had trouble with keyboard input in anaconda for CentOS 7. But for Korora 25 it was fine.

Once I installed and rebooted, I switched the display back to “Spice server” and then everything worked smoothly: keyboard and mouse. Maybe I missed some guest additions package or something, because my screen doesn’t resize automatically with the window of the display. But selecting a different screen resolution in the xfce display utility worked just fine!