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---
title: "GSoC'26: Add Hyperlight Platform in KraftKit, Part III"
description: In this third post of my GSoC'26 series, I share how we brought pre-built base runtimes, automated CI workflows, and multi-language application examples to Hyperlight in Unikraft.
publishedDate: 2026-08-05
image: /images/hyperlight/gsoc_hyperlight_hero.png
authors:
- Jaidev Singh
tags:
- gsoc
- gsoc26
- kraftkit
- hyperlight
- unikraft
- catalog
---

## Project Overview

Welcome to the third post in my GSoC'26 series!

In [Part I](/blog/2026-06-19-unikraft-gsoc-hyperlight-platform), I introduced Hyperlight and walked through implementing the initial Hyperlight machine driver in KraftKit, complete with performance benchmarks against QEMU and Firecracker.
In [Part II](/blog/2026-07-14-unikraft-gsoc-hyperlight-platform-2), we added unit and end-to-end tests to make sure the machine driver stays rock-solid as KraftKit and `hyperlight-unikraft` evolve.

With the core driver built and tested, the next big goal was developer experience.
How can someone take an existing application written in C, Rust, Zig, Go, or Python and run it on Hyperlight in seconds without compiling a Unikraft kernel from source every single time?

In this post, I'll share how we made Hyperlight support official in KraftKit, built the pre-built `base-hyperlight` runtime in `catalog`, automated image builds in CI, and created polyglot application examples to show it off.

## Merging Hyperlight into KraftKit Upstream

Some great news: official support for the Hyperlight platform has been merged into KraftKit ([#2888](https://github.com/unikraft/kraftkit/pull/2888)) and is now available as of the [`v0.12.15`](https://github.com/unikraft/kraftkit/releases/tag/v0.12.15) release!
I'm glad to be a part of it.

This integration brings together the driver work, CLI flags (`--hyperlight-stack`, `--hyperlight-net`, etc.), validation, and testing suites into KraftKit.
Additionally, we updated KraftKit's CI build environments (`github-action` images) to include `hyperlight-unikraft` tools out of the box, ensuring future pull requests can build and validate Hyperlight targets automatically.

## Instant Execution with `base-hyperlight`

Unikraft's secret sauce is its modularity — compiling a custom kernel tailored to a specific application yields ultra-small, hyper-optimized binaries.
But during rapid development or when running standard pre-compiled binaries, developers want instant startup.

To solve this, we introduced `base-hyperlight` (`library/base-hyperlight`) in the Unikraft [catalog](https://github.com/unikraft/catalog).

`base-hyperlight` is a general-purpose ELF-loader runtime pre-configured for the Hyperlight platform (`plat: hyperlight`, `arch: x86_64`).
It packages an ELF loader (`app-elfloader`) alongside the POSIX features required by modern runtimes and compilers:

- **Host Filesystem RPC (`hostfs`)**: Transparent file access auto-mounted at `/host` via Hyperlight host calls (`/dev/hcall`).
- **Proxied Networking (`hostsock`)**: Host-proxied socket support for guest applications.
- **Rootfs Mounting (`cpiovfs`)**: Fast, zero-copy initrd rootfs automounting at `/`.
- **Full POSIX Subsystem**: Support for threading, signals, futexes, `mmap` (via `ukmmap`), multiprocess capabilities (`execve`), and environment variables.

Now, instead of compiling Unikraft kernel source files locally, KraftKit can pull a pre-compiled `base-hyperlight` kernel image and execute user applications immediately.

> Note: While the runtime source definition in the catalog repository lives under [`library/base-hyperlight`](https://github.com/unikraft/catalog/tree/main/library/base-hyperlight), the published OCI image is `base:latest` (`unikraft.org/base:latest`).
> When configuring KraftKit, you simply specify `runtime: base:latest` alongside the target `platform: hyperlight`.

Now you can use the base runtime to run Unikraft unikernels on Hyperlight:

```yaml
spec: v0.7

name: httpserver-gcc13.2-hyperlight

runtime: base:latest

targets:
- platform: hyperlight
architecture: x86_64

rootfs: ./rootfs.cpio

cmd: ["/http_server"]
```

or via CLI:

```bash
kraft run --rootfs rootfs.cpio --plat hyperlight unikraft.org/base:latest -- /bin
```

## Automated CI Workflows for Base Images

A base runtime is only useful if it's readily accessible to everyone.
We updated the catalog's GitHub Actions workflow (`.github/workflows/library-base.yaml`) to include `library/base-hyperlight`.

Now, whenever changes land, GitHub Actions automatically builds and publishes the `hyperlight/x86_64` base runtime image to OCI registries alongside the standard `qemu/x86_64` and `fc/x86_64` targets.
Developers can target `runtime: base:latest` with `--plat hyperlight` and get a fully working setup immediately.

## Hyperlight Examples

KraftKit grabs the `base:latest` image, packs the compiled binary into an initrd, launches the Hyperlight micro-VM, and starts serving requests in milliseconds.
With `base-hyperlight` published, we added a series of new examples under `examples/hyperlight/` to demonstrate running different programming languages on Hyperlight micro-VMs:

### 1. C HTTP Server (`examples/hyperlight/httpserver-gcc13.2`)

A lightweight HTTP server written in C compiled with GCC 13.2

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### 2. Rust HTTP Server (`examples/hyperlight/httpserver-rust1.75`)

A single-file HTTP server written in Rust using std networking.

### 3. Zig Hello World (`examples/hyperlight/helloworld-zig0.11`)

A minimal Zig application running natively on Hyperlight.

## Looking Back on GSoC'26

This project has been an incredible journey.
Over the summer, we went from zero Hyperlight support in KraftKit to:

- A fully functional Hyperlight machine driver supporting volumes, custom flags, logging, and networking;
- Comprehensive unit and end-to-end test suites integrated into KraftKit;
- Upstream integration in `kraftkit` and CI image environments;
- A pre-built `base-hyperlight` ELF-loader runtime published automatically via CI workflows;
- A rich set of polyglot examples in `catalog` spanning C, Rust, Zig, Go, Python, Dotnet, and NodeJS.

Hyperlight brings sub-millisecond boot times and ultra-lightweight microVM isolation.
Pairing it with Unikraft and KraftKit makes running microVM workloads fast, simple, and accessible.

## Acknowledgements

I want to express my deepest gratitude to my mentors ([Cezar Craciunoiu](https://github.com/craciunoiuc) and [Alex-Andrei Cioc](https://github.com/nurof3n)) for their unwavering support, advice, and code reviews throughout GSoC.
Special thanks to [Dan Chiarlone](https://github.com/danbugs) for his invaluable help with Hyperlight host features and initial KraftKit work, and to the entire Unikraft and Hyperlight communities for welcoming me and guiding me through this project.

## About Me

Hi, I'm [Jaidev](https://github.com/ijaidev), a final-year undergraduate student.
Learning and writing code to make the machine work.
FIGURING IT OUT :)
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