An Edge KV store built with Wasm Components

Dan Gohman - Fastly / Benjamin Young - Fastly

Fastly built an Edge Key-Value (KV) store service using Wasm Components. We use Virtual Platform Layering to efficiently isolate user code that can only use public APIs from implementation code that can use private APIs. We’ll show how we built it, why we built it this way, and what we learned.

What is an Edge KV store?

• What does a KV store API look like?
• What’s the “Edge” here?
• What does the user code look like?

Virtual Platform Layering

• The problem: User code shouldn’t be able to call private APIs, but we want to link it with a library that can.
• How Virtual Platform Layering solves this problem.
• Look, no sidecar proxies!
• Bonus ideas: There can be multiple layers…

Fastly’s KV store implementatiton

• Overview of Fastly’s infrastructure
• Let’s look at some example implementation code
• Look, no raw pointers!
• End-to-end overview of how it all fits together
• Lessons learned

Components in production

• How does the compilation pipeline work?
• How we migrated existing infrastructure to support Wasm Components.
• OCI enters the chat