WebAssembly Serverless Functions in Netlify

High-performance functions written in C/C++, Rust, Swift, and other languages can be easily compiled into WebAssembly. Those WebAssembly functions are much faster than JavaScript or Python commonly used in serverless functions.

However, if raw performance is the only goal, why not just compile those functions to machine native executables (Native Client or NaCl)? Netlify already runs these functions safely in AWS Lambda with the Firecracker microVM.

Our vision for the future is to run WebAssembly as an alternative lightweight runtime side-by-side with Docker and microVMs in the cloud

For starters, WebAssembly provides fine-grained runtime isolation for individual functions . A microservice could have multiple functions and support services running inside a microVM. WebAssembly can make the microservice more secure and more stable.

Second, the WebAssembly bytecode is portable . Developers only need to build it once and do not need to worry about changes or updates to the underlying Netlify serverless runtime. It also allows developers to reuse the same WebAssembly functions in other cloud environments.

Third, WebAssembly apps are easy to deploy and manage. They have much less platform dependencies and complexities compared with NaCl dynamic libraries and executables.

Finally, the WasmEdge Tensorflow API provides the most ergonomic way to execute Tensorflow models in the Rust programming language. WasmEdge installs the correct combination of Tensorflow dependency libraries, and provides a unified API for developers.

Our first demo application allows users to upload an image and then invoke a serverless function to turn it into black and white. A live demo deployed on Netlify is available.

The second demo application allows users to upload an image and then invoke a serverless function to classify the main subject on the image.

Running WasmEdge from Netlify’s current serverless container is an easy way to add high-performance functions to Netlify applications. Going forward an even better approach is to use WasmEdge as the container itself. There will be no Docker and no Node.JS to bootstrap WasmEdge. This way, we can reach much higher efficiency for running serverless functions. WasmEdge is already compatible with Docker tools .