I have the following simple code:

use std::{net::SocketAddr, path::Path};

use axum::{extract::{ConnectInfo, Request, State}, middleware::Next, response::{Html, IntoResponse, Response}, routing::{get, get_service}, Extension};
use tower_http::services::ServeDir;

#[derive(Clone, Debug)]
struct AppState {
    something: String
}

#[tokio::main]
async fn main() {

    let state = AppState {
        something: "Hello world!".to_string()
    };

    let app = axum::Router::new()
        .route("/", get(home_get))
        .nest_service("/assets", get_service(ServeDir::new(Path::new("assets"))))
        .fallback(get(home_get).with_state(state.clone()))
        .route_layer(axum::middleware::from_fn_with_state(state.clone(),info_middleware))
        .with_state(state);

    let listener = tokio::net::TcpListener::bind(":::7070").await.unwrap();
    axum::serve(listener, app.into_make_service_with_connect_info::<SocketAddr>()).await.unwrap();
}

async fn home_get(state: State<AppState>, connection_info: Extension<MyConnectionInfo>) -> Response {
    Html(format!("{} You called from: {}",state.something,connection_info.ip)).into_response()
}

#[derive(Clone, Debug)]
pub struct MyConnectionInfo {
    pub ip: String
}

pub async fn info_middleware(addr: ConnectInfo<SocketAddr>, mut request: Request, next: Next) -> Response {
    request.extensions_mut().insert(MyConnectionInfo {ip: addr.to_string()});
    next.run(request).await
}

In a real world example, my state would contain the database pool from sqlx and the info_middleware would do things like ensure token is valid, extract IP address, User agent etc. and make it available to all handlers.

For routing, basically:

1. "/" is to take user to home_get
2. "/assets/favicon.ico" serves the favicon file in the assets folder, and
3. any other routes is to fallback to home_get.

1 and 2 work well. 3 does not.

For example, "/submit" fails with below 500 Internal error:

Missing request extension: Extension of type `fallbackdemo::MyConnectionInfo` was not found. Perhaps you fot to add it? See `axum::Extension`.

I think this is because the Extension middleware isn't accessible to fallbacks?

How to make it work? Or some workaround (other than having to specify every single fallback route manually)?

I have the following simple code:

use std::{net::SocketAddr, path::Path};

use axum::{extract::{ConnectInfo, Request, State}, middleware::Next, response::{Html, IntoResponse, Response}, routing::{get, get_service}, Extension};
use tower_http::services::ServeDir;

#[derive(Clone, Debug)]
struct AppState {
    something: String
}

#[tokio::main]
async fn main() {

    let state = AppState {
        something: "Hello world!".to_string()
    };

    let app = axum::Router::new()
        .route("/", get(home_get))
        .nest_service("/assets", get_service(ServeDir::new(Path::new("assets"))))
        .fallback(get(home_get).with_state(state.clone()))
        .route_layer(axum::middleware::from_fn_with_state(state.clone(),info_middleware))
        .with_state(state);

    let listener = tokio::net::TcpListener::bind(":::7070").await.unwrap();
    axum::serve(listener, app.into_make_service_with_connect_info::<SocketAddr>()).await.unwrap();
}

async fn home_get(state: State<AppState>, connection_info: Extension<MyConnectionInfo>) -> Response {
    Html(format!("{} You called from: {}",state.something,connection_info.ip)).into_response()
}

#[derive(Clone, Debug)]
pub struct MyConnectionInfo {
    pub ip: String
}

pub async fn info_middleware(addr: ConnectInfo<SocketAddr>, mut request: Request, next: Next) -> Response {
    request.extensions_mut().insert(MyConnectionInfo {ip: addr.to_string()});
    next.run(request).await
}

In a real world example, my state would contain the database pool from sqlx and the info_middleware would do things like ensure token is valid, extract IP address, User agent etc. and make it available to all handlers.

For routing, basically:

1. "/" is to take user to home_get
2. "/assets/favicon.ico" serves the favicon file in the assets folder, and
3. any other routes is to fallback to home_get.

1 and 2 work well. 3 does not.

For example, "/submit" fails with below 500 Internal error:

Missing request extension: Extension of type `fallbackdemo::MyConnectionInfo` was not found. Perhaps you fot to add it? See `axum::Extension`.

I think this is because the Extension middleware isn't accessible to fallbacks?

How to make it work? Or some workaround (other than having to specify every single fallback route manually)?

• rust
• rust-axum

1 Answer 1

The reason it doesn't work is because you are using route_layer. It only applies to a specific route, as explained here: https://docs.rs/axum/latest/axum/struct.Router.html#method.route_layer

use layer instead and it will work just fine:

use std::{net::SocketAddr, path::Path};

use axum::{
    extract::{ConnectInfo, Request, State},
    middleware::Next,
    response::{Html, IntoResponse, Response},
    routing::{get, get_service},
    Extension,
};
use tower_http::services::ServeDir;

#[derive(Clone, Debug)]
struct AppState {
    something: String,
}

#[tokio::main]
async fn main() {
    let state = AppState {
        something: String::from("Hello World!"),
    };

    let app = axum::Router::new()
        .route("/", get(home_get))
        .nest_service("/assets", get_service(ServeDir::new(Path::new("assets"))))
        .fallback(get(home_get).with_state(state.clone()))
        .layer(axum::middleware::from_fn_with_state(
            state.clone(),
            info_middleware,
        ))
        .with_state(state);
    let listener = tokio::net::TcpListener::bind(":::7070").await.unwrap();
    axum::serve(
        listener,
        app.into_make_service_with_connect_info::<SocketAddr>(),
    )
    .await
    .unwrap();
}

async fn home_get(
    state: State<AppState>,
    connection_info: Extension<MyConnectionInfo>,
) -> impl IntoResponse {
    Html(format!(
        "{} You called from: {}",
        state.something, connection_info.ip
    ))
}

#[derive(Clone, Debug)]
struct MyConnectionInfo {
    pub ip: String,
}
pub async fn info_middleware(
    addr: ConnectInfo<SocketAddr>,
    mut request: Request,
    next: Next,
) -> Response {
    request.extensions_mut().insert(MyConnectionInfo {
        ip: addr.to_string(),
    });
    next.run(request).await
}