Struct App 

#[non_exhaustive]
pub struct App {
    pub router: Router,
    pub state: Arc<AppState>,
}

The application, ready to serve.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

router: Router

Every route the configuration enables, with its layers and state.

state: Arc<AppState>

The state the routes share, for anything served beside them – the binary’s admin port answers health checks from it.