envoy-wasm-regional-routing

Example Envoy WebAssembly plugin using Rust. This example serves two purposes

1. How to write an Envoy WASM plugin.
2. How to leverage Envoy's WASM support and implement dynamic routing.

For 1. you can also check the references below for more materials. For 2., I configured two regions us_east1 and us_central1. Each cluster has only single endpoint for the purpose of demonstration. Dynamic routing is implemented in a way that given a request with HTTP Host, the plugin sends an async HTTP request to a discovery service (httpbin.org/anything for this demo) and then the discovery service returns a JSON response that instructs Envoy to which cluster request should go. I mocked the discovery service so that for a HTTP Host where its first character's ASCII code is odd it returns us_central and when it is even it returns us_east1. Thus, curl -I -H "Host: google.com" localhost:10000 would be routed to us_central1, which means the request would be proxied to the only endpoint in that cluster that is www.elvinefendi.com. On the other hand curl -I -H "Host: doogle.com" localhost:10000 would go to us_east1 cluster, or httpbin.org endpoint.

How to run

The examples assumes working Rust and Cargo setup, running Docker daemon and Docker Compose installed. Once you have the prerequisites you can build

make build

and then start the proxy

make run

You can test by sending requests to localhost:10000.

References

1. https://github.com/proxy-wasm/proxy-wasm-rust-sdk
2. https://docs.eupraxia.io/docs/how-to-guides/deploy-rust-based-envoy-filter/
3. https://antweiss.com/blog/extending-envoy-with-wasm-and-rust/
4. https://medium.com/safetycultureengineering/edge-routing-with-envoy-and-lua-621f3d776c57