Axum's 'Options' request to non existent route returns 404

[Kimishu]

Summary

I have two services: one on Axum and another one on Actix.
In actix when browser sends Options request to non existent route, server returns 200 when on Axum situation a bit different - it returns 404 instead.

This is my axum's router configuration:

let router = Router::new()
.route(...)
.layer(CorsLayer::permissive())
.layer(
            TraceLayer::new_for_http()
            .make_span_with(trace::DefaultMakeSpan::new().level(Level::INFO))
            .on_response(trace::DefaultOnResponse::new().level(Level::INFO))
            .on_failure({})
)

The main question: is it right or no? Should it be fixed/How to configure this?

axum version

0.8.1

[yanns]

The question is quite open, and is debated in other servers as well: hapijs/hapi#4397
The solution proposed there (adding a fallback to answer with 200 for options requests) can also be applied to axum.

[jplatte]

It should also be possible to apply the CORS layer (and the trace layer around it, if what the CORS layer does should be traced) around the Router, in which case I'm pretty sure this would not happen.

[Kimishu]

It should also be possible to apply the CORS layer (and the trace layer around it, if what the CORS layer does should be traced) around the Router, in which case I'm pretty sure this would not happen.

I already applied CORS layer + TraceLayer. Also added an index handler but it still doesn't work.

1. Frontend app sends Options request and got 404. OPTIONS http://localhost:8000/non-existent-route -> preflight 404
2. Then request to the non-existent resource will return Cors error instead of 404.
   GET http://localhost:8000/non-existent-route -> Cors Error
   And this case is too bad. I have a temporal solution and handle this thing by nginx, but still loking for proper way.

tracing_subscriber::fmt()
        .with_max_level(tracing::Level::DEBUG)
        .init();

    let (router, api) = OpenApiRouter::with_openapi(ApiDoc::openapi())
        .routes(routes!(index::index_handler))
        .routes(routes!(test::test_handler))
        .layer(CorsLayer::permissive())
        .layer(TraceLayer::new_for_http())
        .split_for_parts();
    router
        .merge(SwaggerUi::new("/swagger-ui/").url("/api-docs/openapi.json", api))
        .merge(Redoc::with_url("/redoc", "/api-docs/openapi.json"))

[jplatte]

By applying it "around the router", I meant something like this.