Componentizing Fastly Compute

Erik Rose - Fastly

The WebAssembly component model enables the composition of wasm modules in a high-performance, trustworthy, language-neutral way. See how Fastly is using it to speed execution, save effort, and improve security at the network’s edge in our Compute service.

As an introduction, I’ll enumerate the fruits of the component model: its capability-based security, representation-normalizing binary interface description language, composition tricks, and elegant solution to the function-color problem. See how components let us encapsulate private logic so it can’t exfiltrate secrets. Understand how they bridge language divides so our customers can continue writing in whatever they like while interfacing with what we have.

We’ll then dive into Fastly’s experience deploying components in production, with a selection of war stories culminating in the transparent adaptation of WASIp1 core modules to components, without customers even needing to recompile. Delve into the workings of the component adapter, which must manufacture a convincing façade without so much as a heap allocation. Thrill as we automatically edit customer code to fit the new environment. And see how we turn milliseconds-long network hops into nanoseconds-long function calls, tossing out the complexity and error-proneness of network infrastructure along the way.

Last, come along on a case study where we tool up Python as a new Compute language, made so much easier thanks to components. See how clever memory-freezing obviates the need for a filesystem at runtime, learn how we convince standard CPython to run without POSIX around, and see how the WIT IDL’s richness lets us generate fairly idiomatic APIs.