Title: Wrestling with the WebAssembly Beast

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February 19, 2024 marks another day in my long and winding road of platform engineering. Today, I found myself staring down a particularly daunting challenge involving WebAssembly (Wasm) on the server side—a topic that’s becoming increasingly relevant as AI/LLM infrastructure explodes post-ChatGPT.

The Context: A World of Wasm

For those not in the know, WebAssembly is a binary instruction format designed to be executed by a virtual machine. It’s gaining traction because it allows for compiled code from languages like C/C++ and Rust to run efficiently on modern web browsers, but its potential extends far beyond that. With projects like Emscripten making it possible to compile server-side applications into Wasm, the possibilities are exciting. However, excitement often comes with a hefty dose of pain.

The Problem: A Messy Codebase

At my current gig, we’re exploring the use of WebAssembly for some high-performance tasks that traditionally live on the server. One particular function I’m working on is an image processing module. We’ve got this monolithic codebase written in C++, and converting it to Wasm was going to be no easy feat.

The first issue I ran into was the compiler. While Emscripten works great for browser-based applications, getting it to work seamlessly with our server-side infrastructure took some trial and error. We had to figure out how to set up a build system that could compile our code without stepping on any toes in our existing CI/CD pipeline.

The Debugging Journey

Debugging Wasm can be quite the nightmare. Unlike traditional compiled binaries, Wasm doesn’t have an immediate stack trace or a backtrace when something goes wrong. Instead, you get cryptic error messages and no line numbers to speak of. I spent way too many hours staring at wasm-ld output and lldb sessions trying to figure out why my functions weren’t being called properly.

Finally, after several iterations and a lot of head-scratching, we managed to get the code running. But it wasn’t just about getting it compiled; we had to optimize it for performance too. WebAssembly isn’t magic—it still requires careful tuning to ensure it runs efficiently in environments like ours.

The FinOps Dilemma

With our Wasm module up and running, I couldn’t help but think about the cost implications. As platform engineers, one of the most pressing concerns is cloud cost management—especially when dealing with a new technology that might be resource-intensive. We’re in the throes of a major FinOps push, and every line of code counts.

We ran some benchmarks and found that while our Wasm module was performing well, it was consuming more resources than we initially anticipated. This got me thinking about how to balance performance with cost. Are we optimizing for the wrong metric? Should we be looking at other ways to offload tasks onto Wasm without breaking the bank?

The Future of Platform Engineering

As I reflect on this journey, one thing is clear: WebAssembly isn’t just a shiny new toy; it’s a serious tool that can transform how we build and deploy applications. However, like any powerful technology, it comes with its own set of challenges.

For now, I’m leaning into the learning curve and preparing to ship our Wasm module. There will be more debugging sessions ahead, but I’m excited about what lies on the other side—a platform that can leverage server-side WebAssembly for better performance and innovation.

In the meantime, let’s keep an eye on FinOps and DORA metrics as we navigate this exciting yet complex landscape. After all, in tech, it’s not just about building cool stuff; it’s also about doing so efficiently and responsibly.

Until next time,

Brandon