pn-rust-scaffolding

Rust backend scaffolding

When to use

• Starting a new Rust API project with Axum or Actix-web.
• Adding a new route module or domain handler.
• Setting up a Cargo workspace for multiple crates.

Project structure

# Single binary — Axum
src/
  main.rs             # Entry point: build router, start server
  routes/
    mod.rs            # Collect and export all route modules
    users.rs          # User route handlers
    orders.rs
  services/
    mod.rs
    users.rs          # Business logic
  db/
    mod.rs
    pool.rs           # sqlx pool setup
  models/
    user.rs           # Serde/sqlx types
  errors.rs           # AppError enum + IntoResponse impl
  config.rs           # Typed config from environment

Cargo.toml
.env.example

For larger projects: Cargo workspace with separate crates (api, domain, infrastructure).

Axum scaffold

// src/errors.rs
use axum::{http::StatusCode, response::{IntoResponse, Response}, Json};
use serde_json::json;
use thiserror::Error;

#[derive(Debug, Error)]
pub enum AppError {
    #[error("Not found")]
    NotFound,
    #[error("Forbidden")]
    Forbidden,
    #[error("Validation failed: {0}")]
    Validation(String),
    #[error("Database error: {0}")]
    Db(#[from] sqlx::Error),
    #[error("Internal error")]
    Internal,
}

impl IntoResponse for AppError {
    fn into_response(self) -> Response {
        let (status, code) = match &self {
            AppError::NotFound    => (StatusCode::NOT_FOUND, "NOT_FOUND"),
            AppError::Forbidden   => (StatusCode::FORBIDDEN, "FORBIDDEN"),
            AppError::Validation(_) => (StatusCode::UNPROCESSABLE_ENTITY, "VALIDATION_FAILED"),
            AppError::Db(_)       => (StatusCode::INTERNAL_SERVER_ERROR, "DB_ERROR"),
            AppError::Internal    => (StatusCode::INTERNAL_SERVER_ERROR, "INTERNAL_ERROR"),
        };
        let body = json!({ "error": { "code": code, "message": self.to_string() } });
        (status, Json(body)).into_response()
    }
}