erplibre/script/qemu

QEMU/KVM — Linux VM deployment (Ubuntu / Debian / Fedora)

deploy_qemu.py deploys a Linux VM (libvirt/KVM) from an official cloud image, using qemu-img + cloud-init + virt-install. Pick the distribution with --distro (ubuntu default, debian, fedora) and the release with --version; run --list-images to see the full catalogue with minimum specs. It:

1. Downloads the cloud image by itself (cached, no double download).
2. Converts it to a dedicated qcow2 working disk and resizes it.
3. Generates user-data / meta-data and builds the seed.iso (cloud-init).
4. Runs virt-install importing the disk + the seed as a CD-ROM.
5. Waits for the DHCP lease and prints the SSH command.

Prerequisites

• A host with KVM available (bare-metal or nested virtualization enabled).
• sudo rights (the deployment writes to /var/lib/libvirt/images and drives libvirt).

Installation

The script auto-installs the missing pieces it needs: on first run it detects your package manager (apt / dnf / pacman / zypper / brew), lists the missing components (the client tools, plus the libvirt daemon and the QEMU system emulator), asks for confirmation, installs them with sudo, then enables and starts libvirtd. Use -y to accept automatically or --no-install-deps to disable this behaviour.

To install everything manually on Ubuntu/Debian (recommended full KVM stack):

sudo apt install qemu-utils virtinst libvirt-clients cloud-image-utils \
    libvirt-daemon-system qemu-system-x86
sudo systemctl enable --now libvirtd
sudo usermod -aG libvirt,kvm "$USER"   # re-login / reconnectez-vous

libvirt-daemon-system provides the libvirtd daemon (and the /var/run/libvirt/libvirt-sock socket) and qemu-system-x86 the emulator — without them virt-install fails with "Failed to connect socket to '/var/run/libvirt/libvirt-sock'". The script installs and starts them for you; this manual command is only needed if you prefer to prepare the host yourself or run with --no-install-deps.

Usage

Simplest form — the image is downloaded automatically (path derived from --version, cached in /var/lib/libvirt/images/iso):

sudo ./script/qemu/deploy_qemu.py --name test-vm --version 24.04 \
    --ssh-key ~/.ssh/id_ed25519.pub

Download (and verify) an image without creating a VM:

sudo ./script/qemu/deploy_qemu.py --download-only --version 24.04 --verify

Deploy with an interactive password instead of an SSH key:

sudo ./script/qemu/deploy_qemu.py --name test-vm --version 24.04 --ask-password

Larger VM (8 GB RAM, 8 vCPU, 120 GB disk), overwriting an existing disk:

sudo ./script/qemu/deploy_qemu.py --name test-vm --version 24.04 \
    --memory 8192 --vcpus 8 --disk-size 120G --ask-password --force

Preview what would happen, without doing anything (no sudo, no download):

./script/qemu/deploy_qemu.py --name test-vm --version 24.04 --dry-run

Non-interactive deployment (accept dependency install automatically):

sudo ./script/qemu/deploy_qemu.py --name test-vm --version 24.04 \
    --ssh-key ~/.ssh/id_ed25519.pub -y

Catalog, per architecture (deploy_qemu.py is the source of truth):

Distro	Versions	amd64	arm64	s390x
ubuntu	24.04 (default), 25.10, 26.04	✔	✔	✔
debian	11, 12 (default), 13	✔	✔	—
fedora	41, 42 (default), 43, 44	✔	✔	43 only
almalinux	9 (default), 10	✔	✔	✔
rocky	9, 10 (default)	✔	✔	✔
opensuse	16.0 (default), tumbleweed	✔	✔	✔
arch	latest	✔	—	—
proxmox	9	✔	✔	—

Fedora builds s390x only for the current release, and on a separate tree (fedora-secondary) — hence the single version there.

proxmox is Proxmox VE, and it deserves a word: it publishes no cloud image — its ISO is an installer that formats the disk. So the deployment does what upstream itself documents for every other case, Proxmox VE on Debian: it downloads the Debian trixie cloud image (the very same file, so a Debian 13 and a Proxmox deployment share one download) and the pve packages turn it into a hypervisor — Proxmox kernel, web UI on :8006.

The version number is Proxmox's, not Debian's: PVE 9 = trixie. arm64 has been official since PVE 9 (the upstream trixie Release announces amd64 arm64, and the arm64 index really serves proxmox-ve). s390x is absent and will stay so by this route: the repository has no binary-s390x index at all — the catalog says it before the deployment rather than failing at the first apt.

opensuse covers two distinct products, not two versions of one. Leap 16.0 is numbered and stable (SLE base) and is the default. tumbleweed is the rolling one, kept as a bellwether for breakage to come: its snapshot drift is real, and it demands a full zypper dup before anything can be installed.

Both ship a qpdf above the pikepdf threshold, so the half-hour qpdf build never runs there — which matters under s390x emulation.

Provide an explicit image path as a positional argument to override the automatic download location.

Ubuntu 20.04 and 22.04 were dropped on every architecture: pikepdf needs qpdf 12.2, whose build requires C++20, and focal ships GCC 9 — it does not even publish g++-10 for s390x. Python 3.8, node 10, cargo 0.67 and OpenSSL 1.1.1 each had a workaround; the pile of them did not.

After deployment

virsh list --all
virsh console test-vm                    # Ctrl+] to quit / pour quitter
virsh domifaddr test-vm --source lease   # find the IP / trouver l'IP
ssh erplibre@<IP>

The default user is erplibre (change it with --user).

Via the TODO menu

The script is integrated into the interactive assistant. Run make todo (or ./script/todo/todo.py), then go to Execute → Deploy → QEMU/KVM - Deploy an Ubuntu VM (libvirt). From there you can deploy a VM, preview a dry-run, download an image, list VMs and show a VM IP address — the menu asks for the parameters and builds the command for you.

When a VM is graphical, the menu also offers a check list of development tools: PyCharm Community (installed from the official JetBrains archive into /opt/pycharm, its launcher opening the ERPLibre checkout — the Community line, because the unified 2025.3 build stops on a licence screen and never opens a project), Android Studio (/opt/android-studio, command studio or android-studio; x86_64 only — Google publishes no Linux aarch64 build) and a set of suggested GNOME extensions.

The extension packages of the distribution are installed but left disabled — their UUID is not reliably known, and the Extension Manager is there to pick from. Three extensions named by UUID are installed and enabled, straight from extensions.gnome.org: gTile, Freon and Tracker. The archive is fetched for the GNOME Shell version actually running in the VM — the same endpoint serves gTile v59 for GNOME 46 and v62 for GNOME 48, so a frozen URL would install a build made for another release. A mismatched build is never loaded by GNOME anyway: it compares metadata.json with its own version and shows the extension as outdated rather than breaking the session.

The tools are installed before the clone and the ERPLibre install, and the order matters: PyCharm writes the repository's .idea/ the first time it opens the project, and the install that follows runs pycharm_configuration.py on it (update_env_version.pycharm_update(), which skips silently when there is no .idea yet). That first open is automated: PyCharm runs once under Xvfb — a virtual framebuffer inside the guest, so the orchestrating host needs no graphics at all — with the trust, privacy and data-sharing dialogs answered in advance. Measured on an Ubuntu 26.04 VM with 16 GB: .idea/ is written in 195 s, and the install then adds its exclusions to the .iml. When Xvfb is unavailable or the IDE does not get there in five minutes, the log says so and the install carries on.

A fourth one needs no desktop at all: ERPLibre mobile (build). It adds the mobile repository to the manifest (which is additive, so it coexists with an Odoo 18 install), runs the repository's own install-android.sh — JDK 17, command-line tools, SDK licences accepted, NDK, whisper.cpp and sentencepiece — then builds: npm ci, vite build, cap sync, gradlew assembleDebug, and finally npm test. A failed build fails the VM: the exit code reaches the dashboard, and the log names the probable cause instead of leaving a 40 MB Gradle log to read: disk full, missing SDK platform, JDK/Gradle mismatch, unaccepted licences, a Gradle daemon killed by the kernel (with the machine's RAM, swap and oom-kill count, because a memory cause is proven and not assumed), or too many asset files for one APK. The heavy output goes to ~/erplibre-mobile-build.log inside the VM so the install log stays readable.

That last cause is fixed rather than avoided. The app carries the manifest repositories so their code can be browsed offline, and an APK is a ZIP capped at 65535 entries — one file per source asked for 123 678 and the build stopped there. Those files now enter as packs: 4 MB slices, plus an index.json per repository saying which slice holds a file, at which offset and length. The reader asks for a byte range, and falls back to the whole slice when the WebView server ignores Range — 4 MB at worst, which is why the slices are bounded. Raster images are left out: addon screenshots, in a browser that shows text.

Images are packed too, and a packed file has no URL of its own: the reader turns its bytes into a blob URL. Gettext catalogues, on the other hand, are dropped — 41 594 .po/.pot files weighing 857 MB, 72 % of the payload for content that Weblate maintains and nobody reads on a phone. BUNDLE_KEEP_PO=1 brings them back, BUNDLE_SKIP_IMG=1 drops the images.

Measured on a VM: 139 repositories, 80 841 files in 233 slices, an APK of 354 MB with 2 844 entries, and 20 files read back from the packs identical byte for byte to their source. The APK does not follow the payload — text compresses, PNG does not: the code alone is 331 MB of assets for about 130 MB of APK. The install verifies the transfer with script/mobile/check_bundle_transfer.py, which also runs on its own, and a failed transfer fails the VM — an app that does not carry the code it is meant to show is not the app that was asked for.

It is bounded to apt-based distributions, because that upstream installer starts with sudo apt install openjdk-17-jdk. It requires no Android Studio — a plain server VM builds the APK — and when Android Studio is also ticked they share one SDK through ANDROID_HOME. Without Android, the same app runs in a browser: npm start.

A fifth, Android emulator (Pixel), creates an AVD. Drive it from the QEMU menu, Android emulator (start, tunnel, scrcpy): it starts the emulator without a window and hands you the adb tunnel and the scrcpy command. Prefer that to a window over X11 — scrcpy receives H.264 encoded by the device, where ssh -X ships every frame as raw pixels in software rendering. If you do want the window, the path must be absolute, because ssh host 'command' reads neither ~/.profile nor ~/.bashrc: ssh -XC erplibre@<ip> '$HOME/android/emulator/emulator -avd erplibre -no-audio'.

It needs no desktop in the VM, but it does need KVM inside the guest, so nested virtualisation on the host; the log says so when /dev/kvm is missing. The device is not frozen: the SDK is asked for its profiles and the newest plain Pixel with the smallest screen wins (no Pro, XL, Fold or tablet). Rendering is swangle in the AVD's own config.ini — auto would open a black screen, and swiftshader_indirect no longer exists, the emulator answering Selected GPU option ... is not valid.

A sixth, Forgejo, installs a self-hosted git forge — the software behind Codeberg — from the project's official static binary, and leaves it serving on port 3000 with git-over-SSH on 2222. Like the mobile build it needs no desktop, and unlike it no package family is excluded: the binary is static, so the same file serves apt, dnf, pacman and zypper. That is what makes it portable across the ERPLibre platforms without a branch per distribution. Architectures follow upstream, which publishes amd64, arm64 and arm-6 — the checkbox greys out on s390x rather than dropping a binary that cannot run.

The work lives in script/forgejo/install_forgejo.sh, callable on its own for an existing machine: ./script/forgejo/install_forgejo.sh. It verifies the published checksum, writes all four secrets itself so the service never needs to rewrite its own configuration, and stores its data in SQLite so it does not dispute PostgreSQL with Odoo on the same VM. Replaying it is cheap and safe — 1.5 s measured with everything in place: it skips a binary already at the right version, never overwrites an existing app.ini, and does not recreate the administrator. FORGEJO_VERSION, FORGEJO_HTTP_PORT, FORGEJO_ADMIN_USER and a few others tune it; --help lists them.

Each tool is filtered per VM — by architecture, desktop flavour and package family — and its disk cost is added to the plan before anything is created.

Main options

• --distro — ubuntu (default), debian or fedora.
• --version — release for the distro (default: the distro's default).
• --list-images — print all distros/versions and their specs, then exit.
• --image-dir — image cache directory (default /var/lib/libvirt/images/iso).
• --download-only — download the image then exit (no VM).
• --name — VM name (required for deployment).
• --memory, --vcpus, --disk-size — VM sizing. When omitted, --memory and --disk-size default to the minimum required by the chosen version (libosinfo values, see --list-images: Ubuntu 24.04+ → 3072 MB/20G, Debian → 1024 MB/10G, Fedora → 2048 MB/15G); --vcpus defaults to 2.
• --ssh-key, --ask-password, --password-hash — authentication.
• -y / --assume-yes — auto-accept dependency installation.
• --no-install-deps — never auto-install dependencies.
• --dry-run — show the commands without executing anything.
• --force — overwrite the existing working qcow2 disk.
• --gpu — 3D acceleration by the host GPU: auto (default, on when the host has a render node), on (force), off (software rendering).
• --gpu-node — which render node to use, on a multi-GPU host.
• --lang — language of the SSH login guide, fr (default) or en. The TODO menu passes its own language.
• --erplibre-dir — where ERPLibre will live in the VM (~/git/erplibre, or /opt/erplibre in production). Adds the ERPLibre section to the login guide; omitted, that section is left out.
• --erplibre-make — the make target that installed the VM (e.g. install_odoo_18), shown in the guide as the way to update it.
• --no-git-identity — do not copy the host's user.name, user.email and core.editor into the VM's ~/.gitconfig.

Run ./script/qemu/deploy_qemu.py --help for the full list.

Login guide (/etc/motd)

Every VM greets you, at each interactive SSH login, with the commands of its own distribution — apt, dnf, zypper or pacman — plus the ERPLibre ones (edit the server, restart it, update modules, update Odoo, inspect the instance, open the TODO menu). It is written by cloud-init, so it is there from the first boot: before ERPLibre is installed, and still there if that installation fails, which is exactly when you log in by hand.

--dry-run prints the generated guide along with the rest of the user-data. The guide is not shown to ssh host 'command', so it never pollutes an installation log.

The host's git identity travels with it, into the VM's ~/.gitconfig: a commit made in the VM then carries your name instead of erplibre@<vm-name>. The editor follows the same route — core.editor, the config.conf line of the guide, and the package installed in the VM all come from one table, so the guide never names a command the VM does not have.

Managing VMs

List, stop and remove VMs (the qcow2 disk under /var/lib/libvirt/images is kept unless you delete it):

sudo virsh list --all          # toutes les VM et leur état / all VMs and state
sudo virsh shutdown <nom-vm>   # arrêt propre ACPI / graceful shutdown
sudo virsh destroy <nom-vm>    # arrêt forcé / force off (pull the plug)
sudo virsh undefine <nom-vm>   # supprime la définition / remove definition
sudo virsh domifaddr <nom-vm>  # adresse IP de la VM / VM IP address

destroy only powers the VM off (disk kept); undefine removes its definition. To fully recreate a VM with the same name, destroy + undefine it first, or redeploy with --force.

The VMs' subnet

Every VM deployed here lives in the libvirt network default, which serves a /24 — 192.168.122.0/24 out of the box. The VMs take an address in it by DHCP and leave through its .1, carried by the bridge. Move that /24 under a running VM and it keeps a lease that leads nowhere; tear the network down and its tap is no longer on any bridge, which libvirt does not undo by itself.

network_qemu.py reads that state, and puts the subnet back under the VMs:

# What the network serves, its bridge, its VMs, their leases — reads only
./script/qemu/network_qemu.py --status

# Put the subnet back: stop the attached VMs, redefine, start them again
./script/qemu/network_qemu.py --recreate
./script/qemu/network_qemu.py --recreate --prefix 192.168.140
./script/qemu/network_qemu.py --recreate --force-off   # VMs that ignore ACPI

The default prefix is libvirt's own, 192.168.122: it is what the .ssh/config entries and the notes written before assume. A prefix that overlaps what the host already routes is refused — a bridge taking the host's gateway address is how a machine loses its own network. A VM that ignores the shutdown cancels the redefinition rather than losing its bridge under it.

Both are also at TODO › Execute › Deploy › QEMU/KVM, section Network.

SSH access from another machine (ProxyJump)

With the default NAT network the VM is reachable only from the KVM host. To reach it from another machine without changing the network, use the host as a jump host (it already reaches the VM). Get the VM IP with sudo virsh domifaddr <nom-vm>, then from the other machine:

# Rebond SSH vers la VM / jump through the KVM host
ssh -J user@<ip-hote> erplibre@<ip-vm>

# Tunnel d'un service, ex. Odoo 8069 / tunnel a service, then http://localhost:8069
ssh -L 8069:<ip-vm>:8069 user@<ip-hote>

To make it permanent, add this to ~/.ssh/config on the other machine (then just ssh myvm):

Host myvm
    HostName <ip-vm>            # ex. 192.168.122.50 (reseau NAT)
    User erplibre
    ProxyJump user@<ip-hote>    # IP LAN de l'hote KVM

This works over Wi-Fi and needs no VM shutdown — the simplest option for personal access. Prefer a bridge (below) if the VM must be a full server exposed on the LAN.

3D acceleration (host GPU)

A graphical VM without acceleration renders everything on the CPU — the desktop, and the Android emulator running inside it. The deployment therefore takes the host GPU by default (--gpu auto): when the host exposes a render node, the VM gets a virtio-GPU with accel3d plus an egl-headless display that carries the OpenGL context beside the VNC console — it opens no port and replaces nothing. No render node, no 3D, and the deployment says why instead of quietly falling back.

ls /dev/dri/renderD*             # the GPU QEMU can use — empty means no 3D
sudo virsh dumpxml <vm-name> | grep -A2 -E "accel3d|egl-headless"

An existing VM is adjusted from the TODO menu while it is shut off: libvirt only reads these settings when QEMU starts. QEMU/KVM › List VMs › [2] Change the state, then either accept Adjust hardware before starting, or take [3] Adjust hardware only. In a form when Textual is available, in prompts otherwise, it sets:

• vCPU, RAM, autostart — the plain sizing knobs.
• CPU mode — host-passthrough (what the fleet uses) hands the host CPU instructions over as they are: that is what makes nested virtualization possible inside the VM. host-model describes an equivalent model, migratable to another machine.
• Screens — the virtio-GPU heads, which becomes max_outputs on the QEMU command line. vram is deliberately not offered: on a virtio-GPU libvirt writes it into the XML and QEMU never receives it (check with virsh domxml-to-native — only max_outputs shows up). Only qxl uses vram.
• Network — the libvirt networks and the host bridges, the latter to put the VM on the LAN (see the bridge section below). Switching keeps the MAC address and the PCI slot, so the guest finds its card again — same interface name, same DHCP lease.

Two things worth knowing:

• A host that is itself a VM has no render node unless a GPU was handed down to it. Nested without passthrough, 3D is out of reach: the Android emulator then runs on SwiftShader, and no option changes that.
• Once the VM does have 3D, the emulator can be tried with -gpu host instead of its default -gpu swangle: EL_EMULATOR_GPU=host ./todo.sh. It stays a manual test — an emulator whose GL context fails hangs instead of falling back, so swangle remains the default.

QEMU inside QEMU (nested) & exposing the VM via a bridge

If the KVM host is itself a VM (QEMU-in-QEMU), the deployment works only when nested virtualization is enabled on the outer/physical host and the middle VM uses CPU mode host-passthrough. Check from inside the KVM host (the first command must be non-empty):

grep -E -o '(vmx|svm)' /proc/cpuinfo | sort -u   # extensions visibles / visible
# Sur l'hote PHYSIQUE / on the PHYSICAL host:
cat /sys/module/kvm_intel/parameters/nested      # Intel -> Y/1
cat /sys/module/kvm_amd/parameters/nested        # AMD   -> Y/1

To enable nesting on the physical host (Intel shown; use kvm_amd on AMD), then recreate the middle VM with host-passthrough:

echo "options kvm_intel nested=1" | sudo tee /etc/modprobe.d/kvm-nested.conf
sudo modprobe -r kvm_intel && sudo modprobe kvm_intel   # ou / or reboot

On s390x and arm64 the parameter lives on the kvm module itself, not on kvm_intel / kvm_amd — and /sys/module/kvm/parameters/nested does not even exist on x86. Reading the wrong file returns a reassuring 0 that commands nothing:

echo "options kvm nested=1" | sudo tee /etc/modprobe.d/kvm-nested.conf
sudo modprobe -r kvm && sudo modprobe kvm               # ou / or reboot

nested on a machine means « let MY guests run VMs ». To accelerate a VM created on host H, the setting belongs to the hypervisor above H, not to H itself. The one command that settles it, run on H:

ls -l /dev/kvm     # absent -> pas d'imbrication, tout sera émulé

Measured on an s390x host that was itself a KVM guest without nesting: /dev/kvm absent, virsh dumpxml showing <domain type='qemu'>, and a 7 min 30 boot instead of well under a minute. systemd-detect-virt inside the VM is not proof of acceleration — on s390x, QEMU fabricates the STSI answer and reports kvm even under TCG. Only <domain type=…> on the host is conclusive.

If nesting is unavailable, QEMU still runs via software emulation (TCG) — it works but is slow.

# /etc/netplan/01-br0.yaml
network:
  version: 2
  renderer: networkd
  ethernets:
    enp3s0: {dhcp4: no, dhcp6: no}
  bridges:
    br0:
      interfaces: [enp3s0]
      dhcp4: yes
      parameters: {stp: false, forward-delay: 0}

Apply safely (auto-reverts if you lose the connection) and verify — or use NetworkManager (Ubuntu desktop):

# netplan
sudo netplan try && sudo netplan apply
ip addr show br0        # br0 porte l'IP du LAN / br0 holds the LAN IP

# NetworkManager (alternative)
nmcli con add type bridge ifname br0 con-name br0
nmcli con add type ethernet ifname enp3s0 master br0 con-name br0-port
nmcli con modify br0 ipv4.method auto
nmcli con down "Wired connection 1" ; nmcli con up br0

Then attach the VM to the bridge — either at creation:

sudo ./script/qemu/deploy_qemu.py --name <nom-vm> --version 24.04 \
    --ssh-key ~/.ssh/id_ed25519.pub --network bridge=br0,model=virtio -y --force

or by editing a VM already created: stop it, replace its <interface> block (type='network' / <source network='default'/> → type='bridge' / <source bridge='br0'/>), then start it again:

sudo virsh shutdown <nom-vm>
sudo virsh edit <nom-vm>        # mettre l'interface en bridge=br0
sudo virsh start <nom-vm>
sudo virsh domifaddr <nom-vm>   # nouvelle IP LAN / new LAN IP

The VM now gets a LAN IP from your router, reachable by other machines. From the Internet you additionally need a port-forward on your router (or a VPN); in a nested setup the outer host must also forward/expose the middle VM.