HTTP Handler in Rust

This project template is a WebAssembly component built with Rust that demonstrates an HTTP handler with routing, query parameters, and JSON request and response bodies.

The component uses axum for routing, wired to wasi:http/incoming-handler via wstd-axum. Standard axum runs on tokio plus hyper. Inside a Wasm component, HTTP arrives through the host-imported wasi:http interface, so neither tokio's networking stack nor hyper's socket layer applies. wstd-axum adapts an axum::Router onto the wasi:http/incoming-handler export. The Cargo.toml opts out of axum's default features and only enables those that do not require tokio or hyper.

Prerequisites

• Wasm Shell (wash)
• Rust toolchain
• The wasm32-wasip2 Rust target: rustup target add wasm32-wasip2

Local development

Use wash new to scaffold a new wasmCloud component project:

wash new https://github.com/wasmCloud/wasmCloud.git --name http-handler --subfolder templates/http-handler

cd http-handler

To build this project and run in a hot-reloading development loop, run wash dev from this directory:

wash dev

Endpoints

Endpoint	Method	Description
/	GET	Returns a hello message
/api/greet	GET	Returns Hello, <name>! (uses the name query parameter, defaults to world)
/api/echo	POST	Echoes the JSON request body

Send requests to the running component

curl http://localhost:8000/
curl 'http://localhost:8000/api/greet?name=Eric'
curl -X POST http://localhost:8000/api/echo \
  -H 'Content-Type: application/json' \
  -d '{"message":"hello"}'

Build Wasm binary

wash build

WIT Interfaces

This component exports the following WIT interfaces:

world http-handler {
  export wasi:http/incoming-handler@0.2.2;
}