AxumとActix-web: Rustで本番環境向けREST APIを構築する

cargo new rust-api && cd rust-api

# Cargo.toml
[dependencies]
axum = "0.7"
tokio = { version = "1", features = ["full"] }
sqlx = { version = "0.7", features = ["postgres", "runtime-tokio-native-tls", "uuid", "chrono"] }
serde = { version = "1", features = ["derive"] }
serde_json = "1"
thiserror = "1"
anyhow = "1"
tower-http = { version = "0.5", features = ["cors", "trace"] }
tracing = "0.1"
tracing-subscriber = { version = "0.3", features = ["env-filter"] }
uuid = { version = "1", features = ["v4", "serde"] }
dotenv = "0.15"

// src/state.rs
use sqlx::PgPool;

#[derive(Clone)]
pub struct AppState {
    pub db: PgPool,
    pub config: AppConfig,
}

#[derive(Clone)]
pub struct AppConfig {
    pub jwt_secret: String,
    pub allowed_origins: Vec<String>,
}

// src/main.rs
use axum::{Router, middleware};
use sqlx::postgres::PgPoolOptions;
use tower_http::cors::CorsLayer;
use tower_http::trace::TraceLayer;
use std::sync::Arc;

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    dotenv::dotenv().ok();
    tracing_subscriber::fmt()
        .with_env_filter("rust_api=debug,tower_http=debug")
        .init();

    let database_url = std::env::var("DATABASE_URL")?;
    let pool = PgPoolOptions::new()
        .max_connections(20)
        .connect(&database_url)
        .await?;

    // Run migrations at startup
    sqlx::migrate!("./migrations").run(&pool).await?;

    let state = Arc::new(AppState {
        db: pool,
        config: AppConfig {
            jwt_secret: std::env::var("JWT_SECRET")?,
            allowed_origins: vec!["https://yourdomain.com".to_string()],
        },
    });

    let app = Router::new()
        .nest("/api/v1", api_router())
        .layer(TraceLayer::new_for_http())
        .layer(CorsLayer::permissive()) // tighten in production
        .with_state(state);

    let listener = tokio::net::TcpListener::bind("0.0.0.0:3000").await?;
    tracing::info!("Listening on {}", listener.local_addr()?);
    axum::serve(listener, app).await?;
    Ok(())
}

// src/models/post.rs
use serde::{Deserialize, Serialize};
use sqlx::FromRow;
use uuid::Uuid;
use chrono::{DateTime, Utc};

#[derive(Debug, Serialize, Deserialize, FromRow)]
pub struct Post {
    pub id: Uuid,
    pub title: String,
    pub content: String,
    pub author_id: Uuid,
    pub created_at: DateTime<Utc>,
    pub updated_at: DateTime<Utc>,
}

#[derive(Debug, Deserialize)]
pub struct CreatePost {
    pub title: String,
    pub content: String,
}

// src/db/posts.rs
use sqlx::PgPool;
use uuid::Uuid;
use crate::models::post::{Post, CreatePost};
use crate::error::AppError;

pub async fn get_posts(pool: &PgPool, limit: i64, offset: i64) -> Result<Vec<Post>, AppError> {
    let posts = sqlx::query_as!(
        Post,
        r#"
        SELECT id, title, content, author_id, created_at, updated_at
        FROM posts
        ORDER BY created_at DESC
        LIMIT $1 OFFSET $2
        "#,
        limit,
        offset
    )
    .fetch_all(pool)
    .await?;

    Ok(posts)
}

pub async fn create_post(
    pool: &PgPool,
    author_id: Uuid,
    payload: CreatePost,
) -> Result<Post, AppError> {
    let post = sqlx::query_as!(
        Post,
        r#"
        INSERT INTO posts (id, title, content, author_id, created_at, updated_at)
        VALUES ($1, $2, $3, $4, NOW(), NOW())
        RETURNING *
        "#,
        Uuid::new_v4(),
        payload.title,
        payload.content,
        author_id,
    )
    .fetch_one(pool)
    .await?;

    Ok(post)
}

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

#[derive(Error, Debug)]
pub enum AppError {
    #[error("Database error: {0}")]
    Database(#[from] sqlx::Error),

    #[error("Not found: {0}")]
    NotFound(String),

    #[error("Unauthorized")]
    Unauthorized,

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

    #[error("Internal error")]
    Internal(#[from] anyhow::Error),
}

impl IntoResponse for AppError {
    fn into_response(self) -> Response {
        let (status, message) = match &self {
            AppError::NotFound(msg) => (StatusCode::NOT_FOUND, msg.clone()),
            AppError::Unauthorized => (StatusCode::UNAUTHORIZED, "Unauthorized".to_string()),
            AppError::Validation(msg) => (StatusCode::UNPROCESSABLE_ENTITY, msg.clone()),
            AppError::Database(e) => {
                tracing::error!("Database error: {:?}", e);
                (StatusCode::INTERNAL_SERVER_ERROR, "Database error".to_string())
            }
            AppError::Internal(e) => {
                tracing::error!("Internal error: {:?}", e);
                (StatusCode::INTERNAL_SERVER_ERROR, "Internal server error".to_string())
            }
        };

        (status, Json(json!({ "error": message }))).into_response()
    }
}

// src/handlers/posts.rs
use axum::{
    extract::{Path, Query, State},
    http::StatusCode,
    Json,
};
use serde::Deserialize;
use std::sync::Arc;
use uuid::Uuid;

use crate::{db, error::AppError, models::post::CreatePost, state::AppState};

#[derive(Deserialize)]
pub struct Pagination {
    pub limit: Option<i64>,
    pub offset: Option<i64>,
}

pub async fn list_posts(
    State(state): State<Arc<AppState>>,
    Query(pagination): Query<Pagination>,
) -> Result<Json<Vec<crate::models::post::Post>>, AppError> {
    let limit = pagination.limit.unwrap_or(20).min(100);
    let offset = pagination.offset.unwrap_or(0);

    let posts = db::posts::get_posts(&state.db, limit, offset).await?;
    Ok(Json(posts))
}

pub async fn create_post(
    State(state): State<Arc<AppState>>,
    // In production, extract author_id from JWT claims
    Json(payload): Json<CreatePost>,
) -> Result<(StatusCode, Json<crate::models::post::Post>), AppError> {
    if payload.title.trim().is_empty() {
        return Err(AppError::Validation("Title cannot be empty".to_string()));
    }
    if payload.title.len() > 200 {
        return Err(AppError::Validation("Title too long (max 200 chars)".to_string()));
    }

    let author_id = Uuid::new_v4(); // Replace with JWT extractor
    let post = db::posts::create_post(&state.db, author_id, payload).await?;
    Ok((StatusCode::CREATED, Json(post)))
}

pub fn api_router() -> Router<Arc<AppState>> {
    Router::new()
        .route("/posts", axum::routing::get(list_posts).post(create_post))
        .route("/posts/:id", axum::routing::get(get_post_by_id))
}

# Build stage
FROM rust:1.78-slim as builder
WORKDIR /app
COPY . .
RUN cargo build --release

# Runtime stage
FROM debian:bookworm-slim
RUN apt-get update && apt-get install -y ca-certificates && rm -rf /var/lib/apt/lists/*
COPY --from=builder /app/target/release/rust-api /usr/local/bin/rust-api
RUN useradd -m appuser
USER appuser
EXPOSE 3000
CMD ["rust-api"]