KEI/VyOS_CloudInit/imageBuildFromISO.md

Image was built using Debian 12, kernel 6.1.0-50-cloud-amd64, Docker version 29.6.1, build 8900f1d

Built date is 12/07/2026

Here, an existing rolling release ISO is modified to include qemu-guest-agent and to be CloudInit capable instead of building the whole QCOW2 image from the ground up.

First download the prerequisites

sudo apt update

sudo apt install -y \
    git \
    make \
    qemu-system-x86 \
    qemu-utils \
    wget \
    gpg \
    lsb-release

Install Packer from HashiCorp’s repository

wget -O - https://apt.releases.hashicorp.com/gpg |
    sudo gpg --dearmor \
        -o /usr/share/keyrings/hashicorp-archive-keyring.gpg

echo \
"deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/hashicorp-archive-keyring.gpg] \
https://apt.releases.hashicorp.com \
$(grep -oP '(?<=UBUNTU_CODENAME=).*' /etc/os-release || lsb_release -cs) main" |
    sudo tee /etc/apt/sources.list.d/hashicorp.list

sudo apt update
sudo apt install -y packer

Verify everything

packer version
qemu-system-x86_64 --version
qemu-img --version

test -e /dev/kvm && echo "KVM available" || echo "KVM unavailable"
egrep -m1 '(vmx|svm)' /proc/cpuinfo

Clone packer-vyos

ISO_SOURCE="./vyos-2026.03-generic-amd64.iso"
VM_NAME="$(basename "$ISO_SOURCE" .iso)"

cp "$ISO_SOURCE" "iso/${VM_NAME}.iso"

Create and verify checksums

cd iso
sha256sum "${VM_NAME}.iso" > SHA256SUM
cd ..

cat iso/SHA256SUM
sha256sum -c iso/SHA256SUM

First, remove the VyOS current repository from the temporary APT source used by Packer

sed -i \
    '\|dev.packages.vyos.net/repositories/current|d' \
    http/debian_12-vyos.list

Now replace the script that normally reinstalls Cloud-Init

cat > scripts/vyos/cloud-init-vyos.sh <<'EOF'
#!/bin/bash

set -euo pipefail
set -x

if [[ "${CLOUD_INIT:-}" != "vyos" ]]; then
    echo "VyOS Cloud-Init preservation not requested; skipping"
    exit 0
fi

# Fail rather than silently replacing the Stream ISO's Cloud-Init package.
if ! dpkg-query -W -f='${Status}\n' cloud-init 2>/dev/null |
    grep -qx 'install ok installed'; then
    echo "ERROR: The installed VyOS image does not contain cloud-init."
    exit 1
fi

# Enable the existing VyOS-patched Cloud-Init installation.
systemctl enable cloud-init.service

# Do not let generic Cloud-Init networking conflict with VyOS interface
# configuration. Interfaces will be configured using vyos_config_commands.
mkdir -p /etc/cloud/cloud.cfg.d

cat > /etc/cloud/cloud.cfg.d/99-disable_network_config.cfg <<'CFG'
network: {config: disabled}
CFG

# Match the image-builder behaviour: do not execute generic config-stage
# modules. VyOS-specific user-data processing remains available.
cat > /etc/cloud/cloud.cfg.d/90-disable_config_stage.cfg <<'CFG'
cloud_config_modules:
CFG

rm -f /etc/network/interfaces.d/50-cloud-init
EOF

chmod +x scripts/vyos/cloud-init-vyos.sh

The repository normally installs vim and net-tools during stage two. They are unnecessary for this image, so make that script a no-op

cat > scripts/vyos/apt-install.sh <<'EOF'
#!/bin/bash

set -euo pipefail

echo "Skipping optional vim and net-tools installation"
EOF

chmod +x scripts/vyos/apt-install.sh

The Makefile checks specifically for local-vyos-1.5.pkrvars.hcl, not merely local.pkrvars.hcl, so create it

cat > local-vyos-1.5.pkrvars.hcl <<EOF
ssh_username = "vyos"
ssh_password = "vyos"

# Exact ISO basename without ".iso"
vm_name = "${VM_NAME}"

# Causes scripts/vyos/platform-qemu.sh to install qemu-guest-agent
platform = "qemu"

# Keep and configure the VyOS-patched Cloud-Init from the Stream ISO
cloud_init = "vyos"

# Allow Proxmox NoCloud and ConfigDrive sources
cloud_init_datasource = "nocloud_configdrive"

# Stream 2026.03 belongs to the Circinus/1.5 generation
vyos_release = "circinus"

# Serial console for Proxmox
grub_serial = 1

# Automated build without VNC
headless = true

# Size in MB: 10 GiB
disk_size = 10240
EOF

Create a minimal .env

cat > .env <<'EOF'
PACKER_LOG=1
PARALLEL_BUILDS=1
SLEEP_BEFORE_SHUTDOWN=0

# Leave these unset so Packer selects available ports.
# VNC_PORT_FIXED=
# HOST_PORT_FIXED=
EOF

Initialize Packer. The target initializes the QEMU plugin for all supported templates

make init

Optional validation

packer validate \
    -var-file=local-vyos-1.5.pkrvars.hcl \
    vyos-image1-1.5.pkr.hcl

packer validate \
    -var-file=local-vyos-1.5.pkrvars.hcl \
    vyos-image2-1.5.pkr.hcl

Build stage one

make build1-1.5