---
layout: docs
page_title: 'Drivers: firecracker-task-driver'
description: >-
  The Firecracker task driver is used to run
  firecracker(https://firecracker-microvm.github.io/) microvms.
---

# Firecracker task Driver

Name: `firecracker-task-driver`

The Firecracker task driver provides an interface for creating Linux microvms.
For more detailed instructions on how to set up and use this driver, please
refer to the [documentation][firecracker-task-guide].

## Task Configuration

```hcl
task "test01" {
  driver = "firecracker-task-driver"

  config {
    KernelImage = "/home/build/hello-vmlinux.bin"
    Firecracker = "/home/build/firecracker"
    Vcpus       = 1
    Mem         = 128
    Network     = "default"
  }
}
```

The firecracker task driver supports the following parameters:

- `KernelImage` - (Optional) Path to the kernel image to be used on the microvm.
  Defaults to 'vmlinux' in the [allocation working directory].

- `BootDisk` - (Optional) Path to the ext4 rootfs to boot from.
  Defaults to 'rootfs.ext4' in the [allocation working directory].

- `BootOptions` - (Optional) Kernel command line options to boot the microvm.
  Defaults to "ro console=ttyS0 reboot=k panic=1 pci=off"

- `Network` - (Optional) Network name of your container network configuration
  file.

- `Vcpus` - (Optional) Number of CPUs to assign to microvm.

- `Cputype` - (Optional) CPU template to use, templates available are C3 or T2.

- `Mem` - (Optional) Amount of memory in Megabytes to assign to microvm.
  Defaults to 512

- `Firecracker` Location of the firecracker binary, the option could be omitted
  if the environment variable FIRECRACKER_BIN is setup. Defaults to
  '/usr/bin/firecracker'

- `DisableHt` - (Optional) Disable CPU Hyperthreading. Defaults to false

- `Log` - (Optional) path to file where to write firecracker logs.

## Networking

Network configuration is setup using CNI plugins, the steps to setup firecracker
task driver with cni are the following:

- Build [cni plugins][container network plugins] and [tc-redirect-tap][tc-redirect-tap]
  and copy them to `/opt/cni`.

- Create a network configuration to be used by micro-vms on /etc/cni/conf.d/,
  for example: default.conflist.

### Example network configuration

```json
{
  "name": "default",
  "cniVersion": "0.4.0",
  "plugins": [
    {
      "type": "ptp",
      "ipMasq": true,
      "ipam": {
        "type": "host-local",
        "subnet": "192.168.127.0/24",
        "resolvConf": "/etc/resolv.conf"
      }
    },
    {
      "type": "firewall"
    },
    {
      "type": "tc-redirect-tap"
    }
  ]
}
```

In this example the name of this network is default and this name is the
parameter used in Network on the task driver job spec. Also the filename must
match the name of the network, and use the .conflist extension.

## Client Requirements

`firecracker-task-driver` requires the following:

- Linux 4.14+ Firecracker currently supports physical Linux x86_64 and aarch64
  hosts, running kernel version 4.14 or later. However, the aarch64 support is
  not feature complete (alpha stage)

- The [Firecracker binary][firecracker binary]

- KVM enabled in your Linux kernel, and you have read/write access to /dev/kvm

- tun kernel module

- The firecracker-task-driver binary placed in the [plugin_dir][plugin_dir]
  directory

- ip6tables package

- [Container network plugins][container network plugins]

- [tc-redirect-tap][tc-redirect-tap]

[plugin_dir]: /nomad/docs/configuration#plugin_dir
[tc-redirect-tap]: https://github.com/firecracker-microvm/firecracker-go-sdk/tree/master/cni
[container network plugins]: https://github.com/containernetworking/plugins
[firecracker binary]: https://github.com/firecracker-microvm/firecracker/releases
[firecracker-task-guide]: https://github.com/cneira/firecracker-task-driver
[allocation working directory]: /nomad/docs/runtime/environment#task-directories 'Task Directories'
