Microsoft has taken a significant step forward in its serverless computing ambitions with the announcement of Hyperlight Wasm, a new OS-free host for WebAssembly code. Building on its minimal hypervisor, Hyperlight, Microsoft's latest innovation promises to deliver faster, more secure, and more portable applications, further solidifying its position in the cloud computing market.

Hyperlight Wasm leverages two key features of Hyperlight: its exceptional speed and ability to host guest applications written in various programming languages. In a demo at KubeCon North America, Microsoft showcased Hyperlight's speed by executing multiple functions on micro VMs, spinning up new micro VMs or reusing warm ones to serve requests in microsecond response times. Additionally, the company demonstrated its capability to host a basic JavaScript interpreter written in C, highlighting Hyperlight's flexibility and potential as a serverless computing host.

As a virtual machine host, Hyperlight Wasm requires users to write code to load Hyperlight's guest applications and run the Hyperlight VM. While this may be a challenge for some, hyperscale cloud providers can benefit from Hyperlight's resource efficiency and speed. To overcome compatibility issues, Microsoft recommends using WASI (WebAssembly System Interface) via the open-source Wasmtime runtime, which provides necessary abstractions and enables targeting from any supported language and WebAssembly-ready development environment.

The use of WebAssembly offers several advantages, including the ability to develop and test code without a running Hyperlight environment. This makes it easier to build code that will run on Hyperlight and to use Hyperlight as part of a wider WebAssembly platform. WebAssembly support also expands the range of supported languages for Hyperlight, ensuring that compiled languages, as well as interpreted ones like JavaScript, can be run on a micro VM.

Microsoft has demonstrated the StarlingMonkey WebAssembly-based JavaScript interpreter on Hyperlight, which could pave the way for an Azure Functions-like service. To make Hyperlight Wasm production-ready, the company will need to develop the right tools to manage and run Hyperlight micro VMs. Although still experimental, the Azure team's interest in Hyperlight Wasm is evident, given its potential to reduce capital expenditure by getting better performance from existing hardware at higher densities.

Hyperlight Wasm's minimal API set and isolated memory usage provide a more secure environment for code, making it harder for intruders to subvert applications. WebAssembly's sandboxing capabilities offer an additional layer of security, giving developers not one, but two layers between their code and the host OS.

The Hyperlight Wasm repository on GitHub contains everything needed to experiment, including sample Wasm modules and a host application. To get started, users need Rust, the Just command runner, and the GitHub CLI, as well as virtualization enabled on their systems. Once built, the Hyperlight Wasm implementation can be used to host applications, with three APIs available for working with sandboxed code managed by a SandboxBuilder.

Looking ahead, Microsoft is driving toward a serverless future for Azure, and tools like Hyperlight Wasm will become a key component of its infrastructure. As the platform evolves, we can expect features to change, and once stable, the development of much-needed management tools will provide the necessary user experience for deploying and managing code. With its focus on WebAssembly, Hyperlight Wasm is poised to play a significant role in shaping the future of serverless computing.

As the WebAssembly community continues to define a specification for a component model, Hyperlight Wasm's support for WebAssembly Components will enable code to interoperate easily, allowing for the sharing of binaries and libraries. This architecture-independent approach will ensure portability, enabling service providers to move applications to any spare capacity, regardless of the host virtual machine.