axum-web-framework

name	axum-web-framework
description	Production patterns for Axum 0.8.x HTTP services with Tower middleware, type-safe routing, state management with FromRef, extractors, and error handling. Use when building REST APIs, HTTP services, web applications, or adding middleware to Axum routers.

Axum Web Framework

Production patterns for Axum 0.8.x with Tower middleware and type-safe routing

Version Context

• Axum: 0.8.7 (latest stable)
• Tower: 0.5.2
• Tower-HTTP: 0.6.x
• Tokio: 1.48.0

When to Use This Skill

• Building HTTP REST APIs
• Creating web services with Axum
• Adding middleware (timeout, tracing, compression)
• Managing application state
• Implementing custom extractors
• Handling HTTP errors and responses

Minimal Production Application

use axum::{
    extract::State,
    routing::{get, post},
    Router,
};
use std::sync::Arc;
use tokio::net::TcpListener;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Build shared state
    let state = Arc::new(AppState::new().await?);

    // Build router
    let app = Router::new()
        .route("/health", get(health))
        .route("/users/:id", get(get_user))
        .with_state(state);

    // Start server
    let listener = TcpListener::bind("0.0.0.0:3000").await?;
    axum::serve(listener, app)
        .with_graceful_shutdown(shutdown_signal())
        .await?;

    Ok(())
}

State Management with FromRef

use axum::extract::{State, FromRef};
use std::sync::Arc;

#[derive(Clone, FromRef)]
pub struct AppState {
    pub db: Arc<Database>,
    pub cache: Arc<Cache>,
    pub config: Arc<Config>,
}

impl AppState {
    pub async fn new() -> Result<Self, AppError> {
        let config = Arc::new(Config::load()?);
        let db = Arc::new(Database::connect(&config.db_url).await?);
        let cache = Arc::new(Cache::connect(&config.redis_url).await?);

        Ok(Self { db, cache, config })
    }
}

// Automatic sub-state extraction via FromRef
async fn handler(
    State(db): State<Arc<Database>>,
    State(config): State<Arc<Config>>,
) -> String {
    format!("DB: {}, Config: {:?}", db.status(), config.env)
}

Router Composition

use axum::{Router, routing::{get, post, delete}};

pub fn create_router(state: Arc<AppState>) -> Router {
    Router::new()
        .merge(health_routes())
        .merge(user_routes())
        .merge(order_routes())
        .with_state(state)
}

fn health_routes<S: Clone + Send + Sync + 'static>() -> Router<S> {
    Router::new()
        .route("/health", get(health_check))
        .route("/ready", get(readiness_check))
        .route("/metrics", get(metrics))
}

fn user_routes() -> Router<Arc<AppState>> {
    Router::new()
        .route("/users", post(create_user).get(list_users))
        .route("/users/:id", get(get_user).put(update_user).delete(delete_user))
}

Extractors

Built-in Extractors

use axum::{
    extract::{Path, Query, Json, State},
    http::{HeaderMap, StatusCode},
};
use serde::{Deserialize, Serialize};

#[derive(Deserialize)]
pub struct CreateUserRequest {
    pub email: String,
    pub name: String,
}

#[derive(Deserialize)]
pub struct ListQuery {
    pub page: Option<u32>,
    pub limit: Option<u32>,
}

// Path extraction
async fn get_user(
    State(db): State<Arc<Database>>,
    Path(user_id): Path<String>,
) -> Result<Json<User>, AppError> {
    let user = db.users.find_by_id(&user_id).await?;
    Ok(Json(user))
}

// Query parameters
async fn list_users(
    State(db): State<Arc<Database>>,
    Query(params): Query<ListQuery>,
) -> Result<Json<Vec<User>>, AppError> {
    let page = params.page.unwrap_or(1);
    let limit = params.limit.unwrap_or(20);
    let users = db.users.list(page, limit).await?;
    Ok(Json(users))
}

// JSON body extraction
async fn create_user(
    State(db): State<Arc<Database>>,
    Json(payload): Json<CreateUserRequest>,
) -> Result<(StatusCode, Json<User>), AppError> {
    let user = db.users.create(&payload).await?;
    Ok((StatusCode::CREATED, Json(user)))
}

Custom Extractors

use axum::{
    async_trait,
    extract::FromRequestParts,
    http::{request::Parts, StatusCode},
};

/// Authenticated user extractor
pub struct AuthenticatedUser {
    pub id: UserId,
    pub email: String,
}

#[async_trait]
impl<S> FromRequestParts<S> for AuthenticatedUser
where
    S: Send + Sync,
{
    type Rejection = (StatusCode, String);

    async fn from_request_parts(
        parts: &mut Parts,
        _state: &S,
    ) -> Result<Self, Self::Rejection> {
        // Extract JWT from Authorization header
        let auth_header = parts
            .headers
            .get("authorization")
            .and_then(|v| v.to_str().ok())
            .ok_or((StatusCode::UNAUTHORIZED, "Missing auth header".to_string()))?;

        let token = auth_header
            .strip_prefix("Bearer ")
            .ok_or((StatusCode::UNAUTHORIZED, "Invalid auth header".to_string()))?;

        // Validate token
        let claims = validate_token(token)
            .map_err(|_| (StatusCode::UNAUTHORIZED, "Invalid token".to_string()))?;

        Ok(AuthenticatedUser {
            id: claims.user_id,
            email: claims.email,
        })
    }
}

// Usage in handlers
async fn get_profile(
    user: AuthenticatedUser,
    State(db): State<Arc<Database>>,
) -> Result<Json<UserProfile>, AppError> {
    let profile = db.profiles.find_by_user_id(&user.id).await?;
    Ok(Json(profile))
}

Middleware

Tower Middleware Stack

use tower::{ServiceBuilder, limit::ConcurrencyLimitLayer, timeout::TimeoutLayer};
use tower_http::{
    trace::TraceLayer,
    compression::CompressionLayer,
    cors::CorsLayer,
    limit::RequestBodyLimitLayer,
};
use std::time::Duration;

pub fn create_app(state: Arc<AppState>) -> Router {
    Router::new()
        .route("/api/users", post(create_user))
        .layer(
            ServiceBuilder::new()
                // Observability
                .layer(TraceLayer::new_for_http())
                // Compression
                .layer(CompressionLayer::new())
                // CORS
                .layer(CorsLayer::permissive())
                // Limits
                .layer(RequestBodyLimitLayer::new(1024 * 1024)) // 1MB
                .layer(TimeoutLayer::new(Duration::from_secs(30)))
                .layer(ConcurrencyLimitLayer::new(1000))
        )
        .with_state(state)
}

Custom Middleware

use axum::{
    extract::Request,
    middleware::{self, Next},
    response::Response,
};

/// Request ID middleware
pub async fn request_id_middleware(
    mut request: Request,
    next: Next,
) -> Response {
    let request_id = uuid::Uuid::new_v4();

    // Add to extensions for use in handlers
    request.extensions_mut().insert(RequestId(request_id));

    // Add to response headers
    let mut response = next.run(request).await;
    response.headers_mut().insert(
        "x-request-id",
        request_id.to_string().parse().unwrap(),
    );

    response
}

// Apply to router
let app = Router::new()
    .route("/users", get(list_users))
    .layer(middleware::from_fn(request_id_middleware))
    .with_state(state);

Error Handling with IntoResponse

use axum::{
    response::{IntoResponse, Response},
    http::StatusCode,
    Json,
};

#[derive(Debug, thiserror::Error)]
pub enum AppError {
    #[error("not found")]
    NotFound,

    #[error("database error: {0}")]
    Database(#[from] sqlx::Error),

    #[error("validation error: {0}")]
    Validation(String),
}

impl IntoResponse for AppError {
    fn into_response(self) -> Response {
        let (status, message) = match self {
            AppError::NotFound => (StatusCode::NOT_FOUND, self.to_string()),
            AppError::Database(_) => (
                StatusCode::INTERNAL_SERVER_ERROR,
                "Internal error".to_string(),
            ),
            AppError::Validation(msg) => (StatusCode::BAD_REQUEST, msg),
        };

        let body = Json(serde_json::json!({
            "error": message,
        }));

        (status, body).into_response()
    }
}

// Handlers return Result
async fn handler() -> Result<Json<User>, AppError> {
    let user = db.find_user().await?; // Error automatically converted
    Ok(Json(user))
}

Graceful Shutdown

use tokio::signal;

async fn shutdown_signal() {
    let ctrl_c = async {
        signal::ctrl_c()
            .await
            .expect("failed to install Ctrl+C handler");
    };

    #[cfg(unix)]
    let terminate = async {
        signal::unix::signal(signal::unix::SignalKind::terminate())
            .expect("failed to install signal handler")
            .recv()
            .await;
    };

    #[cfg(not(unix))]
    let terminate = std::future::pending::<()>();

    tokio::select! {
        _ = ctrl_c => {},
        _ = terminate => {},
    }

    tracing::info!("shutdown signal received");
}

// Usage
axum::serve(listener, app)
    .with_graceful_shutdown(shutdown_signal())
    .await?;

Key Patterns

1. State: Use Arc<AppState> with FromRef for sub-state extraction
2. Extractors: Compose multiple extractors in handler signatures
3. Middleware: Apply Tower layers for cross-cutting concerns
4. Errors: Implement IntoResponse for custom error types
5. Modularity: Split routes into separate functions, merge with .merge()

Common Dependencies

[dependencies]
axum = { version = "0.8", features = ["macros"] }
tokio = { version = "1", features = ["full"] }
tower = "0.5"
tower-http = { version = "0.6", features = ["trace", "cors", "compression"] }
serde = { version = "1", features = ["derive"] }
thiserror = "2"