I’m building an emulator for Cloud Run. As I considered the solution, I assumed (more later) that I could implement Google’s gRPC interface for Cloud Run and use Envoy to proxy HTTP/REST requests to the gRPC service using Envoy’s gRPC-JSON transcoder.

Google calls this process Transcoding HTTP/JSON to gRPC which I think it a better description.

Google’s Cloud Run v2 (v1 is no longer published to the googleapis repo) service.proto includes the following Services definition for CreateService:

A digression thanks to Sal Rashid who’s exploring WASM filters w/ Envoy.

The documentation is sparse but:

• How to write WASM filters for Envoy…

There is a Rust SDK but it’s not documented:

• proxy-wasm-rust-sdk

I found two useful posts by Rustaceans who were able to make use of it:

• Extending Envoy with WASM and Rust
• Extending Istio with Rust and WebAssembly

Here’s my simple use of the SDK’s examples.

wasme

curl -sL https://run.solo.io/wasme/install | sh
PATH=${PATH}:${HOME}/.wasme/bin
wasme --version

It may be possible to avoid creating an account on WebAssemblyHub if you’re staying local.