Client

Beta Feature: The Virt task driver is in beta and under active development. Refer to the repo README for the latest updates. Do not use this driver in production environments.

The virt task driver is not built into Nomad. You must downloaded onto the client host in the configured plugin directory. The client host must also be capable of running hardware accelerated KVM virtual machines, which you can check by using kvm-ok command. Additional requirements:

Linux
Commands bridge-utils, cloudinit, dnsmasq, and iptables
libvirt daemon installed and running
QEMU system packages installed
Nomad client running as root

Use the following command to install the package requirements:

$ sudo apt-get update && \
  sudo apt-get install -y \
  bridge-utils \
  cloud-init \
  dnsmasq \
  iptables \
  libvirt-daemon-system \
  qemu-system \
  qemu-system-x86 \
  qemu-utils

Client capabilities

The virt task driver implements the following driver capabilities.

Feature	Implementation
`nomad alloc signal`	false
`nomad alloc exec`	false
filesystem isolation	image
network isolation	host
volume mounting	false

Plugin configuration

This example shows the default plugin configuration.

plugin "nomad-driver-driver" {
  config {
    data_dir     = "/var/lib/virt"
    image_paths  = ["/var/lib/virt", "${ALLOC_DIR}"]

    emulator {
      uri      = "qemu:///system"
      user     = ""
      password = ""
    }
  }
}

data_dir - (default: "/var/lib/virt") - the directory for storing VM configuration files and intermediate files.
image_paths - (default: ["/var/lib/virt", "${ALLOC_DIR}"]) - an allow-list of paths the driver is allowed to load an image from.
emulator - (block)
- uri - (default: "qemu:///system") - The uri specifies which hypervisor to connect to.
- user - (default: "") - the username to use for authentication.
- password - (default: "") - the password to use for authentication.

Client attributes

When installed, the virt plugin provides the following node attributes that you can use as constraints when authoring jobs.

driver.virt                              = true
driver.virt.active                       = 0
driver.virt.emulator.version             = 8002002
driver.virt.inactive                     = 0bytes
driver.virt.libvirt.version              = 10000000
driver.virt.network.default.bridge_name  = virbr0
driver.virt.network.default.state        = active