http-wasm Guest Library

This library provides a Rust implementation for the Wasm Guest ABI and interfaces with http-wasm.

It is designed for writing Traefik plugins in Rust, and works with any http-wasm compatible runtime.

Design Goals

Not opinionated, the focus is to provide a very thin wrapper around the host functions.
Minimal dependency footprint: only the log crate is required at runtime.
Low-level Byte abstraction to enable all use-cases.
Memory-efficient data handling to suit constrained Wasm environments.

Credits

Initial reference code from http-wasm-rust
API inspired by http-wasm-guest-tinygo

Usage

Add the dependency to your project:

cargo add http-wasm-guest

Implement the Guest trait and register the plugin. See the examples for complete code.

use http_wasm_guest::{
    Guest,
    host::{Request, Response},
    register,
};
struct Plugin {}

impl Guest for Plugin {
    fn handle_request(&self, request: &Request, _response: &Response) -> (bool, i32) {
        request.header().add(b"X-Custom-Header", b"FooBar");
        (true, 0)
    }
}

fn main() {
    let plugin = Plugin {};
    register(plugin);
}

Build

Add the WASM target for building the plugin:

rustup target add wasm32-wasip1

Build the library with

cargo build --target wasm32-wasip1 --release

Test

You can run the examples via the provided run.sh script. This creates a running container for the traefik-server with the plugin configured and the whois-service wired into the router.

$ ./run.sh header
[lots of logging output]