Stuck at implementation of middleware #1113

SiddheshKanawade · 2022-06-22T12:08:15Z

SiddheshKanawade
Jun 22, 2022

I am trying to integrate Casbin with Axum to implement a access control middleware. I am using this template to implement the middleware.
I am getting the following error:

It seems I am not able to properly define Service, but not sure where I am going wrong

Following is the relevant code:

impl<S> Layer<S> for CasbinAxumService {
    type Service = CasbinAxumMiddleware<S>;

    fn layer(&self, service: S) -> Self::Service {
        CasbinAxumMiddleware {
            enforcer: self.enforcer.clone(),
            service: Rc::new(RefCell::new(service)),
        }
    }
}

#[derive(Clone)]
pub struct CasbinAxumMiddleware<S> {
    service: Rc<RefCell<S>>,
    enforcer: Arc<RwLock<CachedEnforcer>>,
}

impl<S> Service<Request<Body>> for CasbinAxumMiddleware<S>
where
    S: Service<Request<Body>, Response = Response> + Send + 'static,
    S::Future: Send + 'static,
{
    type Response = S::Response;
    type Error = S::Error;
    // `BoxFuture` is a type alias for `Pin<Box<dyn Future + Send + 'a>>`
    type Future = BoxFuture<'static, Result<Self::Response, Self::Error>>;

    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
        Poll::Ready(Ok(self.service.poll_ready(cx)))
    }

    fn call(&mut self, mut request: Request<Body>) -> Self::Future {
        let future = self.service.call(request);
        Box::pin(async move {
            let response: Response = future.await?;
            Ok(response)
        })
    }
}

Answered by davidpdrsn

Jun 22, 2022

You probably don't want to use Rc<RefCell<S>> inside a middleware. Why do you think you need that? Usually we recommend cloning the inner service.

Also if you just wanna write a middleware for your app and don't mind using something axum specific then I recommend https://docs.rs/axum/latest/axum/middleware/fn.from_fn.html. See https://docs.rs/axum/latest/axum/middleware/index.html#writing-middleware for the trade offs.

View full answer

davidpdrsn · 2022-06-22T15:01:27Z

davidpdrsn
Jun 22, 2022
Collaborator

You probably don't want to use Rc<RefCell<S>> inside a middleware. Why do you think you need that? Usually we recommend cloning the inner service.

Also if you just wanna write a middleware for your app and don't mind using something axum specific then I recommend https://docs.rs/axum/latest/axum/middleware/fn.from_fn.html. See https://docs.rs/axum/latest/axum/middleware/index.html#writing-middleware for the trade offs.

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Stuck at implementation of middleware #1113

SiddheshKanawade Jun 22, 2022

Replies: 1 comment

davidpdrsn Jun 22, 2022 Collaborator

SiddheshKanawade
Jun 22, 2022

davidpdrsn
Jun 22, 2022
Collaborator