How to properly type the GovernorLayer?

[DoneDeal0]

Hello, I would like to extract your limiter in a function, to import it from a separate file in an Axum server.

use axum::{Router, routing::get};
use dotenvy::dotenv;
use std::{env, sync::Arc};

mod middleware;
mod models;
mod router;
use middleware::cors::get_cors;
use router::user::user_routes;

use tower_governor::{GovernorLayer, governor::GovernorConfigBuilder};

fn get_rate_limiter() {
    let rate_limiter = Arc::new(
        GovernorConfigBuilder::default()
            .per_second(2)
            .burst_size(5)
            .finish()
            .unwrap(),
    );
    GovernorLayer {
        config: get_rate_limiter(),
    }
}

#[tokio::main]
async fn main() {
    dotenv().ok();
    let server_port = env::var("SERVER_PORT").unwrap();
    let app = Router::new()
        .nest("/", user_routes())
        .layer(get_cors())
        .layer(get_rate_limiter());
    let listener = tokio::net::TcpListener::bind(&server_port).await.unwrap();
    println!("🔥 Server running on {}", server_port);
    axum::serve(listener, app).await.unwrap();
}

The get_rate_limiter return the following type error:

mismatched types expected unit type () found struct GovernorLayer<_, _>

So I wrote

fn get_rate_limiter() -> GovernorLayer<PeerIpKeyExtractor, _> {}

And the error is refined to:

cannot find type RateLimitingMiddleware in this scope

It seems i can't import RateLimitingMiddleware. How to fix this typing issue? Thanks!

[Pawel-Zygmunt]

@benwis please export also NoOpMiddleware<QuantaInstant> as we can't just import it from governor package itself. It gives an error: Note: two types coming from two different versions of the same crate are different types even if they look the same

Also it can be solved by creating custom middleware, but how to add it to GovernorConfig later?

[hristogochev]

This crate is compatible with up to 0.8 governor, if you use that version of governor your imports will succeed.