Creating a Windows image and making it ready for OpenShift Virtualization requires  installing and configuring several services and drivers.. This should be repeated each time you have  a new update from Microsoft or Red Hat, which may become error-prone and time consuming.

Lucky, there is a better way. Windows has a feature called unattended installation - similar to a kickstart file for RHEL - that is used as an answer file to the entire installation wizard. You could also add drivers and post scripts to complete the installation.

Windows Unattended XML

There is a windows tool called “Windows System Image Manager” (WSIM) that helps build the Unattended installation. You can find more information on how to use it in Microsoft’s documentation: (https://docs.microsoft.com/en-us/windows-hardware/customize/desktop/wsim/windows-system-image-manager-overview-topics )

Note: Windows Unattended installation may vary between different versions of Windows such as Windows Server 2019 , Windows Server Core 2019 etc. If you are supporting multiple Windows versions, we recommend creating a version of the Unattended XML for each version.

Post Installation Script

After installing the operating system, we need to add a few more services to support the Openshift Virtualization platform. During the Unattended installation we will add auto-login for the Administrator and a Powershell script for the first time logon.

In the post installation script, we will install  the Qemu Guest Agent and some additional Drivers, you can also add your own Service / application if needed.

At the end of the script we are disabling the Auto-Login feature and running sysprep with the shutdown option to complete the installation.

Running the Installation

Prerequisites

  • Red Hat Enterprise Linux

Download the Windows image

In this guide we are using Microsoft Windows 2019 evaluation Server image which can be downloaded from the Microsoft website

https://www.microsoft.com/en-US/evalcenter/evaluate-windows-server-2019?filetype=ISO

  1. Get an answer file and a post-installation script

Using the unattended installation XML and post script to complete the installation, drivers and Services.

Autounattended.xml

post-install.ps1

Install required packages

In some cases you would like to see the installation running, for that you will need to install the ”virt-viewer” package.

For a CI pipeline the UI is not needed.

yum install -y libvirt virt-install virtio-win

systemctl start libvirtd

# for console  access

yum install -y virt-viewer

Prepare Windows Image

In order to run the installation we need to add the unattended file and the postscript to the windows image.

Mount windows ISO

sudo mkdir -p /mnt/windows /mnt/windows2019-unattended

sudo mount WindowsServer2019_en-us.iso /mnt/windows

Copy ISO and files to a temp directory

sudo cp -rp /mnt/windows/* /mnt/windows2019-unattended

sudo cp autounattend.xml /mnt/windows2019-unattended

sudo cp post-install.ps1  /mnt/windows2019-unattended

Create a new bootable ISO from the temp directory

genisoimage -allow-limited-size   -no-emul-boot  \

            -b boot/etfsboot.com   -boot-load-seg 0x07C0 \

            -boot-load-size 8  -lJR -o ~/windows2019-unattended.iso \

             /mnt/windows2019-unattended

 

Run the Installation process

First, we need to create a disk image file

qemu-img create -f qcow2 windows2019.qcow2 12G

Don't forget to add the “qemu” user permission to the working directory

sudo setfacl -m u:qemu:rx $(pwd)

Next, we will run the installation script

NAME=windows2019

VIRTIO_ISO=/usr/share/virtio-win/virtio-win.iso

IMAGE_PATH=~/windows2019-unattended.iso

 

virt-install  --connect qemu:///system \

                  --name $NAME --ram 2048 --vcpus 2 \

                  --network model=virtio \

                  --disk path=$NAME.qcow2,format=qcow2,device=disk,bus=virtio \

                  --cdrom $IMAGE_PATH \

                  --disk path=$VIRTIO_ISO,device=cdrom \

                  --vnc --os-type windows --os-variant win2k19

If you’re running as a non-root user you should add the user to the libvirt group

sudo usermod --append --groups libvirt “username”

Depending on the host, the installation will take about 5 - 20 minutes and the command will exit.

If you are running in a CI pipeline / remote server you can remove the “--connect qemu:///system” option from the command line

Finally we have a disk Image ready to be uploaded to the OpenShift Virtualization. First we will switch to the “openshift-virtualization-os-images” project and then push the image with the “virtctl” command.

virtctl image-upload pvc win2k19 \

        --image-path=windows2019.qcow2 --size=13Gi \

        --namespace openshift-virtualization-os-images

In this command, we are using the “win2k19” as the image name. This name is taken from the image templates mentioned in https://github.com/kubevirt/common-templates.

If you’re running the cluster with self-sign certificate / untrusted certificate you should add the “--insecure” option to ignore the certificate verification.

To use the newly added image just create a new VM from wizard and select the windows2019 image. This will correlate to the image name with used “win2k19”

That’s it! We have a Windows Server 2019 image ready to be used. You can also add your own custom script and installation to the “post-install.ps1” if you want to install Anti-virus or some other application.


Categories

How-tos, OpenShift 4, Windows Containers, Images

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