packer-kvm

Create VM templates with Packer for usage with Libvirt/KVM virtualization : AlmaLinux 9, Almalinux 10, Rocky 9, Rocky 10, Fedora 40, Noble (Ubuntu 2404), Debian 12 (Bookworm).

Only for education and learning purposes. Do not use it in production.

Packer Concepts

Packer is an open source tool for creating identical machine images for multiple platforms from a single source configuration called a template. (Introduction to Packer, What is Packer?). It uses different plugins as builders, provisioners or post-processors.

While the JSON format template is still supported, certain new features in the Packer core will only be implemented for the newer HCL2 format. Therefore, this project has been updated to HCL2.

Builders are responsible for creating machines and generating images from them for various platforms. For example, there are separate builders for EC2, VMware, VirtualBox, Qemu, etc. Packer comes with many builders by default, and can also be extended to add new builders. (Builders)

Packer can enable an http server to serve kickstart, preseed or cloud-init configuration files at boot.

Provisioners use builtin and third-party software to install and configure the machine image after booting. (Provisioners)

Post-processors run after the image is built by the builder and provisioned by the provisioner(s). (Post-Processors)

Proof of Concept to generate Linux qemu images

This is a Packer "Proof of Concept" with :

• qemu/kvm as image builder (qcow2)
• "shell" and "ansible-local" as provisionners
• "shell-local" as post-processor to generate a gns3a appliance file, checksum and upload to a server

Optionnal :

• run this inside a docker container
• build your own container

Enjoy those images with :

• Libvirt native tools
• Terraform as IaC tool with a third party Libvirtd Provider plugin

The built images are intended to be published on a S3 bucket.

Pre-requisites

The run this project with success, you need a virtualization server and some softwares installed :

• Libvirt/KVM, Packer and aws s3 cli
• Docker (to run the build inside a container)

Use ./setup.sh for a quick setup of Libvirt/KVM, Packer and aws s3 cli but please read before the following manual instructions.

For Docker usage, install it and put your aws S3 credits in your ~/.profile.

Anyway, you can remove the post-processor in your image JSON template to avoid S3 upload attemps.

AWS S3

Configure your S3 credits :

echo "export AWS_ACCESS_KEY=<your AWS_ACCESS_KEY>" >> ~/.profile
echo "export AWS_SECRET_KEY=<your AWS_SECRET_KEY>" >> ~/.profile
source ~/.profile

Libvirt and Packer

Install Livirt/KVM on your server :

if [ -f /etc/debian_version ]; then
apt-get update && apt-get -y upgrade
apt-get -y install qemu-kvm libvirt-dev virtinst virt-viewer libguestfs-tools virt-manager uuid-runtime curl linux-source libosinfo-bin
virsh net-start default
virsh net-autostart default
elif [ -f /etc/redhat-release ]; then
yum -y install epel-release
yum -y upgrade
yum -y group install "Virtualization Host"
yum -y install virt-manager libvirt virt-install qemu-kvm xauth dejavu-lgc-sans-fonts virt-top libguestfs-tools virt-viewer virt-manager curl
ln -s /usr/libexec/qemu-kvm /usr/bin/qemu-system-x86_64
fi

Install the Packer binary :

yum -y install wget unzip || apt update && apt -y install wget unzip
latest=$(curl -L -s https://releases.hashicorp.com/packer | grep 'packer_' | sed 's/^.*<.*\">packer_\(.*\)<\/a>/\1/' | head -1)
wget https://releases.hashicorp.com/packer/${latest}/packer_${latest}_linux_amd64.zip
unzip packer*.zip
chmod +x packer
mv packer /usr/local/bin/

Install the plugins:

packer plugins install github.com/hashicorp/qemu
packer plugins install github.com/hashicorp/ansible

Docker

Get Docker and docker-compose :

curl -fsSL https://get.docker.com -o get-docker.sh && sh get-docker.sh
if [ -f /etc/debian_version ]; then
apt-get update && apt-get -y install python3-pip
elif [ -f /etc/redhat-release ]; then
yum -y install python3-pip
fi
pip3 install docker-compose

Build with Packer

Each HCL file is a template for a distribution :

• almalinux9.pkr.hcl
• almalinux10.pkr.hcl
• centos10.pkr.hcl
• rocky9.pkr.hcl
• rocky10.pkr.hcl
• centos9.pkr.hcl
• fedora40.pkr.hcl
• ubuntu2404.pkr.hcl
• debian12.pkr.hcl

For example :

packer build almalinux9.pkr.hcl

nota bene: those file are generated by the ansible playbook build-packer-templates.yaml.

Build with Docker qemu based image

goffinet/packer-qemu is a Docker image for building qemu images with packer and is available on Docker Hub.

docker run --rm \
  -e PACKER_LOG=1 \
  -e PACKER_LOG_PATH="packer-docker.log" \
  -it \
  --privileged \
  --cap-add=ALL -v /lib/modules:/lib/modules \
  -v `pwd`:/opt/ \
  -e AWS_ACCESS_KEY=$AWS_ACCESS_KEY \
  -e AWS_SECRET_KEY=$AWS_SECRET_KEY \
  -w /opt/ goffinet/packer-qemu build almalinux9.pkr.hcl

The script build.sh do it with the template filename as first argument.

./build.sh almalinux9.pkr.hcl

To build the image localy with the Dockerfile :

docker build -t packer-qemu .

Packing monitoring

Packer use VNC to launch a temporary VM, you can check this window with a VNC client like vinagre.

You can have more details from Packet with the env var configured : PACKER_LOG=1.

Cloud images for qemu/KVM/Libvirt built with Packer

I build images for qemu/KVM with this project and I publish them for use in those other IaC projects: Kcli or Terraform with Libvirt/KVM provider.

• almalinux9.qcow2 [md5sum] [sha256sum]
• almalinux10.qcow2 [md5sum] [sha256sum]
• ubuntu2204.qcow2 (Jammy) [md5sum] [sha256sum]
• rocky9.qcow2 [md5sum] [sha256sum]
• rocky10.qcow2 [md5sum] [sha256sum]
• fedora40.qcow2 [md5sum] [sha256sum]
• ubuntu2404.qcow2 (Noble) [md5sum] [sha256sum]
• debian12.qcow2 (Bookworm) [md5sum] [sha256sum]

You can easily download them to /var/lib/libvirt/images with this script :

curl -s -o /usr/local/bin/download-images.sh https://raw.githubusercontent.com/goffinet/virt-scripts/master/download-images.sh
chmod +x /usr/local/bin/download-images.sh
download-images.sh

How to exploit those built images

How to exploit those built images?

• In the old way with Libvirt and some bash scripts
• In a beter way with a tool like Terraform

This is always beter to know how Libvirt is working. Can you read fundamentals about KVM virtualization in french.

Enjoy with Libvirt

Please use the kcli project.

For example:

image="almalinux10"
# Get kcli tool
curl https://raw.githubusercontent.com/karmab/kcli/main/install.sh | sudo bash
# Get the image
kcli download image -P url=http://download.goffinet.org/kvm/${image}.qcow2 ${image}
# Create a test vm
kcli create vm -i ${image} -P memory=2048 -P numcpus=1 -P disks=[50] ${image}
# Test SSH connexion and delete the test VM
chmod 600 sshkeys/id_rsa
sleep 30 && if [ "$(kcli ssh -u root -i sshkeys/id_rsa ${image} 'echo test')" == "test"  ] ; then echo SUCCESS ; else echo ERROR ; kcli delete vm -y ${image} ; fi

Enjoy with Terraform (with libvirt)

This section should be revised

https://github.com/goffinet/terraform-libvirt

Install Terraform 0.13 with a third party Libvirt provider plugin :

echo "security_driver = \"none\"" >> /etc/libvirt/qemu.conf
systemctl restart libvirtd
sudo yum -y install wget unzip || sudo apt update && sudo apt -y install wget unzip
wget https://releases.hashicorp.com/terraform/0.13.2/terraform_0.13.2_linux_amd64.zip
unzip terraform_0.13.2_linux_amd64.zip
chmod +x terraform
mv terraform /usr/local/bin/
wget https://github.com/dmacvicar/terraform-provider-libvirt/releases/download/v0.6.2/terraform-provider-libvirt-0.6.2+git.1585292411.8cbe9ad0.Ubuntu_18.04.amd64.tar.gz
tar xvf terraform-provider-libvirt-0.6.2+git.1585292411.8cbe9ad0.Ubuntu_18.04.amd64.tar.gz
mkdir -p ~/.local/share/terraform/plugins/registry.terraform.io/dmacvicar/libvirt/0.6.2/linux_amd64
cp -r terraform-provider-libvirt ~/.local/share/terraform/plugins/registry.terraform.io/dmacvicar/libvirt/0.6.2/linux_amd64/

Compose your libvirt infrastructure :

git clone https://github.com/goffinet/terraform-libvirt
cd terraform-libvirt/ubuntu_cloudinit
terraform plan
cd ../count
terraform plan

Customization

To customize post-processing

The scripts/push-image.sh generate somme meta-data and push the generated image to a pre-defined S3 Bucket.

To customize this process, you can change the content as it :

#!/bin/bash

name=$IMAGE_NAME
version=$IMAGE_VERSION
image="${name}${version}"
echo "artifacts/qemu/${image} post-processing ..."

Anyway, you can remove the post-processor in your image JSON template to avoid this script call.

Customize SSH keys

To generate the ssh keys for provisionning and put it in the sshkeys/ folder :

ssh-keygen -q -t rsa -N '' -C 'packer-kvm-default-key' -f sshkeys/id_rsa

To get the default ssh private key :

curl https://raw.githubusercontent.com/goffinet/packer-kvm/master/sshkeys/id_rsa

To get the default ssh public key :

curl https://raw.githubusercontent.com/goffinet/packer-kvm/master/sshkeys/id_rsa.pub

How are these Packer templates produced?

An build-packer-templates.yaml Ansible playbook generates the files for each distribution using a custom build_packer_templates role.

ToDo

• unique model : for efficience, a unique template should be sufficient with a data source with these elements (https://devops.stackexchange.com/q/4312).
• random secret for provisonning (https://www.packer.io/docs/templates/engine#template-variables)
• remove swap post-processing
• add versions of post-processing and images meta-datas
• include Windows templates: see rgl/windows-vagrant

Wath are the variants in those templates?

• the iso_urls and the iso_checksum template parameters
• the ssh_username, ssh_password and ssh_private_key_file template parameters as well as sshkey in kickstart files.
• the boot_command and provisioner commands as template parameters
• the configuration file type : kickstart, preseed or cloud-init

Initials credits

• https://github.com/idi-ops/packer-kvm-centos
• https://github.com/jakobadam/packer-qemu-templates
• https://github.com/leonkyneur/packer-qemu
• https://github.com/kaorimatz/packer-templates
• https://github.com/bramford/packer-debian9
• https://github.com/bpetit/packer-templates
• https://github.com/NeCTAR-RC/nectar-images/