fx

building something similar to workerd for fun and learning purposes.

features

• deploy functions written in Rust (see fx-sdk for sdk and apps for examples) compiled to wasm (wasm32-unknown-unknown).
• functions can be triggered by http requests, messages from Kafka topics or by cron schedule.
• functions are async and can handle requests concurrently.
• function input and output can be a stream.
• KV storage.
• sql databases powered by sqlite.
• functions can call other functions via RPC (callee is run in the same thread, so no networking is involved resulting in very low latency).
• log, fetch, random, time apis.
• livereload functions.

still, note that this is a toy project with a lot of apis missing. it is also missing handling for various edge cases/errors.

example function

use { fx_sdk::{self as fx, handler, HttpRequest, HttpResponse}, tracing::info };

#[handler]
pub async fn http(req: HttpRequest) -> fx::Result<HttpResponse> {
    info!("this function is compiled to wasm and is running within fx: {}", req.url);
    Ok(HttpResponse::new().body("hello fx!\n"))
}

see apps for more examples.

performance

fx performs on par with Node.js and at 46% of native Rust.

Runtime	Requests/sec	Latency
fx	17,499	455μs
axum (native Rust)	37,963	221μs
Node.js	17,200	465μs

Benchmark: TechEmpower Fortunes on Hetzner CCX23. See docs/benchmarking.md for details.

usage

invoke functions using cli interface

build hello world example (alternatively, compile your own function to .wasm):

just app-hello-world

then run function using fx:

cargo run -p fx-runtime -- run target/wasm32-unknown-unknown/release/fx_app_hello_world example

expected output:

target/wasm32-unknown-unknown/release/fx_app_hello_world | {"message": Text("hello from fx!")}