lab {} block

wcl block

Declares a lab: a set of VMs plus the virtual networks connecting them, in vmlab.wcl.

A lab is declared with a lab {} block in vmlab.wcl, located by walking up from the current directory (like git). Lab-local working data — linked clones, snapshots, built media, screenshots — lives in .vmlab/ beside it; gitignore that directory. Every WCL file in a lab starts with import <vmlab.wcl>.

§ 1Minimal lab

wcl

import <vmlab.wcl>

lab "demo" {
  gui = true                  // lab-wide default: open a VNC viewer on each guest
                              // when `vmlab up` runs interactively (VM `gui`
                              // overrides; skipped when there is no display)
  vm "box" {
    template = "x86_64/linux-modern"
    memory   = 2GiB
    nic { nat = true }
  }
}

VMs always run headless; gui only decides whether the CLI opens a viewer for you. Closing the viewer merely disconnects — the VM keeps running, and you can reattach any time with vmlab console.

§ 2Examples

§ 2.1A small multi-segment lab

Two segments (one with the DC as DNS, one zero-config), three VMs with static and dynamic leases, a scoped provision and crash handlers.

wcl

import <vmlab.wcl>

lab "ad-lab" {
  segment "corp" {
    subnet = "10.50.0.0/24"
    dns { server = "10.50.0.10" }                 // AD owns DNS
    route { dest = "10.60.0.0/24" via = "10.50.0.254" }
  }
  segment "dmz" { }                               // zero-config: auto subnet, daemon DHCP/DNS

  vm "dc01" {
    template = "x86_64/windows-server-2025"
    cpus = 4  memory = 8GiB
    nic { segment = "corp" ip = "10.50.0.10" }    // static → DHCP reservation

    provision "scripts/setup.ws" { }              // runs once dc01 is ready
  }
  vm "client01" {
    template   = "x86_64/windows-11@26100.1"      // version pin
    depends_on = ["dc01"]                         // boot ordering
    nic { segment = "corp" }                      // dynamic lease
  }
  vm "buildbox" {
    template = "x86_64/linux-modern"
    nic { nat = true }
  }

  on "vm.crashed"    { run = "scripts/collect-dumps.ws" }
  on "host.disk_low" { run = "scripts/alert.ws" }
}