KraftKit 🚀🐒🧰

KraftKit provides a suite of tools and Go-based framework for building custom, minimal, immutable lightweight unikernel virtual machines based on unikraft.org: a fast, secure and open-source library operating system.

[!NOTE] This repository is specific to the Unikraft unikernel, it is not Unikraft Cloud's CLI. Unikraft Cloud is a separate platform that runs microVMs, with its own CLI and commands. For the Unikraft Cloud CLI, see the unikraft CLI documentation.

With KraftKit, you can easily leverage Unikraft and manage specialized, high-performance applications at every stage of their lifecycle: from construction to production.

• Getting started guide 📖
• Key differences between containers and unikernels 🤔
• Join #kraftkit on Unikraft's Community Discord 👾

There are many benefits in running your application as a unikernel: for more information about the performance of unikernels 🚀, the added security 🔒 and a positive impact on the environment 🌱 please check out Unikraft's documentation and the introductory chapters on these impacts

Features

• 🚧 Build, run and package unikernel VMs;
• 🐳 Use existing Dockerfiles and Composefiles;
• 📚 Fetch and run pre-built unikernel from the app catalog;
• 🔥 Run unikernel VMs using QEMU, Xen and Firecracker MicroVM;
• 🤹‍♀️ Daemonless unikernel local VM instance manager;
• ⛅️ Deploy unikernel VMs to the cloud;
• 🍎 Native Linux, macOS and Windows support;
• 📦 Package and push unikernels in OCI format for easy distribution;
• 🚜 ELF binary / POSIX-compatibility support;
• 🧰 Go SDK for building unikernels programmatically; and
• 🚀 much more!

Installation

You can quickly and easily install KraftKit using the interactive installer. Run the following command to get started:

curl --proto '=https' --tlsv1.2 -sSf https://get.kraftkit.sh | sh

Alternatively, you can download the binaries from the releases pages.

See additional installation instructions.

See also the hacking documentation on how to build KraftKit from source.

Container build environment

KraftKit ships a container build environment which you can use instead of installing any dependencies directly on your host. It includes the kraft binary as well as all the additional tools and libraries for building Unikraft unikernels. Attach a working directory on your host as a mount path volume mapped to /workspace, e.g.:

docker run -it --rm -v $(pwd):/workspace --entrypoint bash kraftkit.sh/base:latest

The above command will drop you into a container shell. Type exit or Ctrl+D to quit.

Quickstart

Test your installation

Running unikernels with kraft is designed to be simple and familiar. To test your installation of kraft, you can run the following:

kraft run unikraft.org/helloworld:latest

Build your first unikernel

Building unikernels is also designed to be simple. Build your first unikernel by placing a Kraftfile into your repo and pointing it to your existing Dockerfile:

spec: v0.6

runtime: base:latest

rootfs: ./Dockerfile

cmd: ["/path/to/my-server-app"]

Once done, invoke:

kraft run .

Examples and pre-built images

You can find some common project examples below:

	Example
	Simple "Hello, world!" application written in C
	Simple "Hello, world!" application written in C++
	Simple "Hello, world!" application written in Rust built via cargo
	Simple NodeJS 18 HTTP Web Server with http
	Simple Go 1.21 HTTP Web Server with net/http
	Simple Flask 3.0 HTTP Web Server
	Simple Python 3.10 HTTP Web Server with http.server.HTTPServer

Find more examples and applications in our community catalog!

Use in GitHub Actions

KraftKit can be used to automatically build your application into a unikernel in a GitHub Actions workflow, "use" unikraft/kraftkit@staging.

In the following example, a repository that has been initialized with a top-level Kraftfile that contains a target for qemu/x86_64 will be built every time a PR is opened, synchronized or re-opened:

name: example

on:
  pull_request:
    types: [opened, synchronize, reopened]

jobs:
  build:
    steps:
    - uses: actions/checkout@v4

    - uses: unikraft/kraftkit@staging
      with:
        workdir: .
        kraftfile: Kraftfile
        arch: x86_64
        plat: qemu

For other CI's and integrations, including GitLab, check out the getting started guide.

Compatibility

Hypervisor	Supported Version
Xen	<= 4.19
QEMU	<= 9.2.1 && >= 4.2.0
Firecracker	>= 1.4.1

	QEMU	Firecracker	Xen	containerd
linux/amd64	✅	✅	✅	✅
linux/arm64	✅	✅	--	✅
darwin/amd64	✅	--	--	✅
darwin/arm64	✅	--	--	✅
freebsd/amd64	✅	--	--	✅
freebsd/arm64	✅	--	--	✅
netbsd/amd64	✅	--	--	--
netbsd/arm64	✅	--	--	--
openbsd/amd64	✅	--	--	--
openbsd/arm64	✅	--	--	--

Support, Community & Meetings

If you have any further questions or need more information about KraftKit or Unikraft, please refer to the official Unikraft documentation or ask for help on the Unikraft community forum.

A KraftKit Working Group (WG) meets every other Wednesday at 13:00 PM (CET) on Discord. Invites and additional details are available on the Unikraft OSS Public calendar.

License

KraftKit is part of the Unikraft OSS Project and licensed under BSD-3-Clause.