Declarative labs
A lab {} block declares VMs and the networks between them. Hardware comes from guest OS profiles with clear precedence, so most VMs are a couple of lines — vmlab validate checks it all before boot.
Declarative VM labs · QEMU/KVM
Orchestrate virtual machine labs from your terminal.
vmlab turns a single vmlab.wcl into a running fleet of VMs — machines, networks, and provisioning, wired automatically. Boot, snapshot, and tear down complex topologies with one command.
Open source · MIT · Linux, or Windows 11 via WSL 2 or Docker
import <vmlab.wcl>
lab "demo" {
segment "lan" {
subnet = "10.81.0.0/24"
nat = true // guest egress
forward { host_port = 12222 to = "alp:22" } // host SSH → guest
}
vm "alp" {
template = "ghcr.io/vmlabdev/vmlab-templates/alpine-3.23"
memory = 1GiB
nic { segment = "lan" }
}
provision "scripts/setup.ws" { } // wscript, typed & checked
}
A taste
From a single file to a running lab in one command.
The lab is the file: segments with built-in DHCP, DNS and NAT, VMs booting linked clones of a template — pulled from an OCI registry on first up if it isn't local. vmlab validate type-checks the whole lab (wscript included) before anything boots.
Capabilities
Everything a lab needs, in one binary.
No bridges, no root, no setup step — a per-user daemon pair starts on demand and the whole network fabric runs in userspace.
Powered by QEMU/KVM
Runs x86_64, aarch64, and riscv64 guests from the same tool — KVM-accelerated natively, emulated across arches. No KVM? It falls back to TCG with a loud warning.
Userspace networking
Per-lab virtual switches with DHCP, DNS, NAT, routes, port forwards and L3 filtering — all declared in the lab, no taps, no CAP_NET_ADMIN, no manual wiring.
Snapshots
Capture a single VM or the whole lab, then roll back to any snapshot in seconds.
Guests without networking
Run commands and copy files over the QEMU guest agent — no network path to the VM required, so automation works before the guest is even configured.
OCI distribution
Push templates to any OCI registry as chunked, multi-arch artifacts; reference a registry ref straight from a lab and vmlab up pulls it on demand.
GUI automation & vision
Keystrokes, mouse, screenshots, image matching and OCR — script installers and GUI flows headlessly, even where no agent can run.
wscript provisioning
Provision scripts and event handlers drive guests through a typed API, compiled and type-checked at validate time — handle sysprep, wait for ready, gate the next step on it.
Linked-clone templates
Build a sealed qcow2 template once from installer media; labs boot copy-on-write clones, so templates stay immutable and labs stay small on disk.
Reference
The manual
The reference is published as a wskill — a self-contained WCL model projected into a readable book, a Claude Code skill, an overview deck, and a hands-on training course.
vmlab
A declarative QEMU/KVM VM-lab orchestrator: labs and virtual networks declared in WCL, reusable disk templates built locally or distributed over OCI registries, and guest automation written in wscript.
Getting started
Install it and boot your first lab.
Needs /dev/kvm (on WSL 2 enable nested virtualisation). Or skip the install and run the container image with only --device /dev/kvm: docker run --rm -it --device /dev/kvm ghcr.io/vmlabdev/vmlab.
Install the CLI
curl -fsSL https://vmlab.io/install.sh | sh
Write a lab, then validate it
vmlab validate
Boot it
vmlab up