If you hate cold starts, get ready to celebrate. A routine scan of the latest AWS CLI update (v2.19.0) revealed a hidden parameter that AWS hasn't announced yet: --runtime provided.wasm.
The "Lambda Native" Revolution
Currently, running Rust or Go on Lambda often involves wrapping binaries in a custom runtime or a container. It works, but it's heavy. WebAssembly (WASM) changes the game. It allows code to run at near-native speed in a sandboxed environment that starts up in microseconds, not milliseconds.
What We Found
$ aws lambda create-function help ... --runtimeThe identifier of the function's runtime. Possible values: ... nodejs22.x python3.13 provided.wasm (EXPERIMENTAL)
Why This Matters
Zero Cold Starts
WASM modules are so small and initialize so fast that the concept of a "cold start" effectively vanishes.
Universal Runtime
Write in Rust, compile to WASM. Write in TypeScript (via AssemblyScript), compile to WASM. One runtime to rule them all.
What's Next?
AWS hasn't officially commented, but the presence of this flag suggests a public beta is imminent, likely before the next re:Invent. Savvy developers should start experimenting with compiling their hot paths to WASM now.