vm-images/README.md

vm-images

Shared, locally cached virtual-machine installation media and base images. Downloaded ISO, QCOW2, IMG, VHD, and VHDX files are intentionally excluded from Git.

Download images

Download every supported image:

./download-images.sh

Download or check selected targets:

./download-images.sh debian13
./download-images.sh almalinux10
./download-images.sh fedora44
./download-images.sh ubuntu2604
./download-images.sh virtio-win

The Windows installation ISO is not downloaded because Microsoft's temporary download URLs expire. Place it manually in install-iso/; the script finds it automatically by matching Win, 11, the architecture (x64, or arm64 on arm64 hosts) and .iso in that order (*Win*11*x64*.iso or *Win*11*arm64*.iso, case-insensitive). If several files match, the highest version-sorted name is used. Check which file was picked with ./download-images.sh --print-path windows11 --iso.

To get a fresh temporary URL, nodejs/get-windows-iso-url.js drives Microsoft's download page with headless Chromium (needs Node.js and an installed Chromium, for example from Playwright):

cd nodejs
npm ci                                            # once, installs playwright-core
node get-windows-iso-url.js                       # print the URL for the host architecture
node get-windows-iso-url.js --arch arm64          # choose the architecture explicitly

The script only prints the URL. ./download-images.sh windows11 downloads that URL into install-iso/ like the other images (aria2c, resumable) for the image architecture (VM_IMAGE_ARCH=arm64 for arm64), and skips it when a matching ISO is already there. The all target does not include it.

The URL expires after about 24 hours and may be bound to the IP that requested it, so download from the machine that ran the script. Run it with --help for the language and path options.

Query image paths

The path interface prints one absolute path without downloading anything:

./download-images.sh --print-path debian13
./download-images.sh --print-path almalinux10
./download-images.sh --print-path fedora44
./download-images.sh --print-path ubuntu2604
./download-images.sh --print-path virtio-win
./download-images.sh --print-path windows11
./download-images.sh --print-path windows11 --iso

The Windows target prints the QCOW2 path by default. Add --iso to print its manually supplied installation ISO path. The QCOW2 is named after the detected ISO (for example Win11_25H2_English_x64_v2.iso → base-qcow2/Win11_25H2_English_x64_v2.qcow2); if no ISO is present, an existing *Win*11*x64*.qcow2 (*Win*11*arm64*.qcow2 on arm64) in base-qcow2/ is used instead.

Download URLs can be overridden with DEBIAN_IMAGE_URL, ALMA_IMAGE_URL, FEDORA_IMAGE_URL, UBUNTU_IMAGE_URL, VIRTIO_WIN_ISO_URL, and OPENSSH_WIN_ZIP_URL. Each may list several mirrors of the same file, separated by whitespace; the Fedora image defaults to the TUNA, BFSU and NJU mirrors, and the Ubuntu image to the TUNA, NJU and official cloud-images.ubuntu.com mirrors.

When aria2 is installed (aria2c), an image is downloaded from all of its mirrors at once, with a single connection to each mirror. Without it, curl (or wget) tries the mirrors in order. A partial download is only resumed with the same downloader and mirror list; otherwise it starts over. The Fedora and Ubuntu checksums can be overridden with FEDORA_IMAGE_SHA256 and UBUNTU_IMAGE_SHA256 when using a custom image.

The openssh-win target downloads the Win32-OpenSSH zip matching the architecture into tools-iso/: OpenSSH-Win64.zip on amd64 hosts and OpenSSH-ARM64.zip on arm64 hosts.

Windows installation disk image

QEMU's emulated USB CD-ROM reads the Windows ISO at only a few MB/s on macOS. build-windows-install-disk.sh builds a bootable FAT32 disk image from the ISO (install.wim is split into install.swm parts because of the 4 GB FAT32 file limit); attached as an NVMe disk it is read about 15 times faster.

# macOS (Homebrew), once
brew install wimlib dosfstools gptfdisk mtools
# Debian, once (p7zip-full or udisks2 only for non-root use)
sudo apt install wimtools dosfstools gdisk mtools p7zip-full

./build-windows-install-disk.sh [--force] install-iso/Windows11_..._arm64_....iso

The output defaults to the ISO path with .img in place of .iso. The image is built without root. The ISO has to be read as UDF (its ISO 9660 side only holds a README): macOS uses hdiutil, Linux uses mount -t udf as root, otherwise udisksctl, otherwise 7z extracts it into a temporary directory (which needs the free space of the whole ISO). The *.img file is ignored by Git.

Windows base image

A VM disk can be created as a QCOW2 overlay on a Windows base image, so a new VM does not run Windows Setup again. build-windows-base.sh makes that base image (by default at the path ./download-images.sh --print-path windows11 prints): it installs Windows unattended from the ISO in install-iso/ (it does everything itself: answer file in windows11/seed/, QEMU hardware in windows11/qemu/; this directory has no dependency on any other repository). The answer file boots into audit mode (no account and no credentials are needed), adds the VirtIO drivers from the virtio-win ISO (downloaded if missing) to the driver store and runs sysprep /generalize there as its last step; the script waits for the guest to power off and stores the disk read-only. The image is clean and generic, like a cloud image: nothing but Windows and the VirtIO drivers, with no account, no SSH, no settings, no other hardware-specific drivers and no machine identity. Each VM is configured on its first boot: Windows reads Unattend.xml from the root of an attached CD-ROM during its specialize and OOBE passes (a VM launcher can mount such a seed ISO when it creates a VM disk). It needs qemu, qemu-img, an ISO tool (xorriso, genisoimage or mkisofs) and socat or nc; there is no SSH to the guest.

./build-windows-base.sh [--force] [--compress] [--from-img] [--headless] [OUTPUT.qcow2]

It refuses to replace an existing base image without --force, because the overlays of existing VMs still point at that file. Build to another OUTPUT (for example with a version in its name) and point your VM launcher at it. The installation runs in a scratch directory /var/tmp/build-windows-base.* (set BASE_BUILD_TMPDIR to use another parent; about 25 GB are needed).