Serverless Compute Environment

We built Compute@Edge on WebAssembly, a technology we’ve been collaborating on with the Bytecode Alliance. WebAssembly is uniquely suited to empower developers to write code in their preferred language, then run that code anywhere at near-native speeds.

Lucet, our native WebAssembly compiler and runtime engine, helped us build a platform for fast, safe code execution on Fastly’s edge cloud. We originally looked at existing WebAssembly/multi-tenant runtimes like Google's V8, but its performance and security models led us to build our own. 

Lucet can instantiate WebAssembly modules in under 50 microseconds with just a few kilobytes of memory overhead. By comparison, Chromium’s V8 engine takes about 5 milliseconds, and tens of megabytes of memory overhead, to instantiate JavaScript or WebAssembly programs. By combining WebAssembly and Lucet we believe we offer a faster and more secure experience for our customers than anything available off-the-shelf today.

Compute@Edge creates and destroys a sandbox for each request as it flows through our platform. Operating within microseconds, this cutting-edge technology reduces the attack surface and eliminates side-channel attacks. It also lets us limit the blast radius of buggy code or configuration mistakes from other users and reduces resource contention.

Since day one we’ve been building on the edge with our customizable Varnish Configuration Language that allows for intelligent caching, moving application logic to the network edge, and tailoring experiences based on end user location, language, and device type. 

Compute@Edge frees developers from typical serverless computing constraints by enabling the use of any WebAssembly-supported language. WebAssembly is an intermediate format that is currently compatible with multiple programming languages such as Rust, AssemblyScript, Java, C/C++, .NET, and Go. Compute@Edge supports two languages today, Rust and AssemblyScript (beta), with more to come in the future.