How to use state with a `tower::Service and Pin<Box<dyn Future>>` middleware? #3023

squeaktoy · 2024-11-11T15:01:34Z

squeaktoy
Nov 11, 2024

Summary

I'm working on a project at https://git.sr.ht/~latex/streamlist
I have 3 confusing compilation errors:

error[E0271]: type mismatch resolving `<ServeDir<SetStatus<ServiceFn<fn() -> impl Future<Output = (StatusCode, &str)> {handle_404}>>> as Service<Request<Body>>>::Response == Response<Body>`
  --> src/main.rs:80:17
   |
80 |             app.fallback_service(service);
   |                 ^^^^^^^^^^^^^^^^ expected `Response<ServeFileSystemResponseBody>`, found `Response<Body>`
   |
   = note: expected struct `axum::http::Response<ServeFileSystemResponseBody>`
              found struct `axum::http::Response<axum::body::Body>`
note: required for `XsltMiddleware<ServeDir<SetStatus<ServiceFn<fn() -> impl futures_util::Future<Output = (reqwest::StatusCode, &'static str)> {handle_404}>>>>` to implement `Service<axum::http::Request<axum::body::Body>>`
  --> src/serve.rs:83:9
   |
83 | impl<S> Service<Request> for XsltMiddleware<S>
   |         ^^^^^^^^^^^^^^^^     ^^^^^^^^^^^^^^^^^
84 | where
85 |     S: Service<Request, Response = Response> + Send + 'static,
   |                         ------------------- unsatisfied trait bound introduced here

error[E0593]: function is expected to take 1 argument, but it takes 0 arguments
  --> src/main.rs:80:17
   |
69 |             async fn handle_404() -> (StatusCode, &'static str) {
   |             --------------------------------------------------- takes 0 arguments
...
80 |             app.fallback_service(service);
   |                 ^^^^^^^^^^^^^^^^ expected function that takes 1 argument
   |
   = note: required for `ServiceFn<fn() -> impl futures_util::Future<Output = (reqwest::StatusCode, &'static str)> {handle_404}>` to implement `Service<axum::http::Request<axum::body::Body>>`
   = note: 2 redundant requirements hidden
   = note: required for `XsltMiddleware<ServeDir<SetStatus<ServiceFn<fn() -> impl futures_util::Future<Output = (reqwest::StatusCode, &'static str)> {handle_404}>>>>` to implement `Service<axum::http::Request<axum::body::Body>>`

error: lifetime may not live long enough
   --> src/serve.rs:99:9
    |
96  |       fn call(&mut self, request: Request) -> Self::Future {
    |               - let's call the lifetime of this reference `'1`
...
99  | /         Box::pin(async move {
100 | |             let response: Response = future.await?;
101 | |             let (resp_parts, resp_body) = response.into_parts();
102 | |             let body_bytes = match axum::body::to_bytes(resp_body, usize::MAX).await {
...   |
220 | |             }
221 | |         })
    | |__________^ returning this value requires that `'1` must outlive `'static`

It seems that in the documentation, there is some conflicting info. I designed this around the example in https://docs.rs/axum/latest/axum/middleware/index.html#towerservice-and-pinboxdyn-future but I also need to access the state, which an example is shown for in https://docs.rs/axum/latest/axum/middleware/index.html#accessing-state-in-custom-towerlayers which doesn't seem to have Box::pin or anything like that so that is very confusing. What am I supposed to do here? I want to return a response and not some request.

Another issue seems to be about the way I am using fallback_service. It says that it expected an argument but saw 0, which is odd because I clearly gave it an argument. What's going on here?
I'm starting to doubt if fallback_service is the right choice. I want to have routing like this:

/api for REST API
/ for static file serving, where an api directory should not interfere with /api

fallback_service sounded like the thing that came closest to what I want to achieve but now I'm not so sure. Any ideas about what I can use? Or how I can fix the error?

Thanks in advance.

axum version

0.7.7

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How to use state with a `tower::Service and Pin<Box<dyn Future>>` middleware? #3023

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How to use state with a tower::Service and Pin<Box<dyn Future>> middleware? #3023

squeaktoy Nov 11, 2024

Summary

axum version

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How to use state with a `tower::Service and Pin<Box<dyn Future>>` middleware? #3023

squeaktoy
Nov 11, 2024