---

OpenAPI documentation for Axum using doc comments and macros.

Built on aide, Rovo provides a declarative approach to API documentation through special annotations in doc comments.

Features

• Drop-in replacement for axum::Router
• Doc-comment driven documentation
• Compile-time validation of annotations
• Method chaining support (.get(), .post(), .patch(), .delete())
• Built-in Swagger/Redoc/Scalar UI integration
• Type-safe response definitions
• Minimal runtime overhead
• Editor Integration:
  • VSCode - See VSCODE.md for Visual Studio Code extension with auto-installation, completions, and syntax highlighting
  • Neovim LSP - See NEOVIM.md for editor support with completions, hover docs, and more
  • JetBrains IDEs - See JETBRAINS.md for RustRover, IntelliJ IDEA, and CLion support

Quick Start

use rovo::{rovo, Router, routing::get};
use rovo::{schemars, schemars::JsonSchema};
use rovo::{aide, aide::{axum::IntoApiResponse, openapi::OpenApi}};
use rovo::{extract::State, response::Json};
use serde::Serialize;

#[derive(Clone)]
struct AppState {}

#[derive(Serialize, JsonSchema)]
struct User {
    id: u64,
    name: String,
}

/// Get user information.
///
/// Returns the current user's profile information.
///
/// # Responses
///
/// 200: Json<User> - User profile retrieved successfully
///
/// # Metadata
///
/// @tag users
#[rovo]
async fn get_user(State(_state): State<AppState>) -> impl IntoApiResponse {
    Json(User {
        id: 1,
        name: "Alice".to_string(),
    })
}

#[tokio::main]
async fn main() {
    let state = AppState {};

    let mut api = OpenApi::default();
    api.info.title = "My API".to_string();

    let app = Router::new()
        .route("/user", get(get_user))
        .with_oas(api)
        .with_swagger("/")
        .with_state(state);

    let listener = tokio::net::TcpListener::bind("127.0.0.1:3000")
        .await
        .unwrap();

    axum::serve(listener, app).await.unwrap();
}

Installation

[dependencies]
rovo = { version = "0.3.1", features = ["swagger"] }
axum = "0.8"
serde = { version = "1.0", features = ["derive"] }
tokio = { version = "1", features = ["full"] }

Note: Rovo re-exports aide, schemars, and common axum types (extract, response, http), so you can import them directly from rovo. The axum dependency is still needed for axum::serve().

For detailed API documentation, see docs.rs/rovo.

Feature Flags

Choose one or more documentation UIs (none enabled by default):

• swagger - Swagger UI
• redoc - Redoc UI
• scalar - Scalar UI

Documentation Format

Rovo uses Rust-style documentation with markdown sections and metadata annotations.

Complete Example

/// Get a todo item by ID.
///
/// Retrieves a single todo item from the database. Returns 404
/// if the item doesn't exist.
///
/// # Path Parameters
///
/// id: The todo item's unique identifier
///
/// # Responses
///
/// 200: Json<TodoItem> - Successfully retrieved the todo item
/// 404: () - Todo item was not found
/// 500: Json<ErrorResponse> - Internal server error
///
/// # Examples
///
/// 200: TodoItem {
///   title: "Buy milk".into(),
///   ..Default::default()
/// }
/// 404: ()
///
/// # Metadata
///
/// @tag todos
/// @security bearer_auth
#[rovo]
async fn get_todo(Path(id): Path<i32>) -> impl IntoApiResponse {
    // ...
}

Responses Section

Document HTTP responses with status codes, types, and descriptions:

/// # Responses
///
/// 200: Json<User> - User found successfully
/// 404: () - User not found
/// 500: Json<ErrorResponse> - Internal server error

Format: <status_code>: <type> - <description>

• Status codes must be valid HTTP codes (100-599)
• Type must be valid Rust syntax
• Description explains when this response occurs

Path Parameters Section

Document path parameters for primitive types:

/// # Path Parameters
///
/// id: The user's unique identifier
/// index: Zero-based item index

Format: <name>: <description>

• Parameter names must match the variable bindings in your function signature
• Works with primitives: String, u64, u32, i64, i32, bool, Uuid, etc.
• For tuple paths like Path((a, b)): Path<(Uuid, u32)>, document each parameter

Examples Section

Provide concrete response examples:

/// # Examples
///
/// 200: User { id: 1, name: "Alice".into(), email: "alice@example.com".into() }
/// 404: ()

Format: <status_code>: <rust_expression>

Examples should match the types defined in the Responses section.

Metadata Section

Contains API metadata using @ annotations:

@tag

Group operations by tags (can be used multiple times):

/// # Metadata
///
/// @tag users
/// @tag authentication

@security

Specify security requirements (can be used multiple times):

/// # Metadata
///
/// @security bearer_auth

Security schemes must be defined in your OpenAPI spec. See Tips for details.

@id

Set custom operation ID (defaults to function name):

/// # Metadata
///
/// @id getUserById

Must contain only alphanumeric characters and underscores.

@hidden

Hide an operation from documentation:

/// # Metadata
///
/// @hidden

Special Directives

#[deprecated]

Mark endpoints as deprecated using Rust's built-in attribute:

#[deprecated]
#[rovo]
async fn old_handler() -> impl IntoApiResponse {
    // ...
}

@rovo-ignore

Stop processing annotations after this point (location-independent):

/// Get user information.
///
/// # Responses
///
/// 200: Json<User> - User found successfully
///
/// # Metadata
///
/// @tag users
///
/// @rovo-ignore
///
/// Additional documentation here won't be processed.
/// You can write @anything without causing errors.
#[rovo]
async fn handler() -> impl IntoApiResponse {
    // ...
}

Router API

Basic Usage

use rovo::Router;

let app = Router::new()
    .route("/path", get(handler))
    .with_state(state);

Method Chaining

use rovo::routing::{get, post, patch, delete};

Router::new()
    .route("/items", get(list_items).post(create_item))
    .route("/items/{id}", get(get_item).patch(update_item).delete(delete_item))

Nesting Routes

Router::new()
    .nest(
        "/api",
        Router::new()
            .route("/users", get(list_users))
            .route("/posts", get(list_posts))
    )

Documentation UIs

Router::new()
    .route("/users", get(list_users))
    .with_oas(api)
    .with_swagger("/swagger")
    .with_redoc("/redoc")
    .with_scalar("/scalar")
    .with_state(state)

Use custom OAS route:

Router::new()
    .route("/users", get(list_users))
    .with_oas_route(api, "/openapi")
    .with_swagger("/")
    .with_state(state)

OpenAPI Formats

Rovo automatically serves your OpenAPI specification in multiple formats:

• JSON - /api.json (default)
• YAML - /api.yaml or /api.yml

All formats are automatically available when you use .with_oas() or .with_oas_route().

Examples

See examples/todo_api.rs for a complete CRUD API.

Run with:

cargo run -F swagger --example todo_api

Migration from Axum

Replace imports and add documentation:

// Before
use axum::{Router, response::IntoResponse, routing::get};

async fn handler() -> impl IntoResponse {
    Json(data)
}

// After
use rovo::{Router, routing::get, schemars::JsonSchema};
use rovo::{aide::axum::IntoApiResponse, response::Json};

/// Handler description
///
/// # Responses
///
/// 200: Json<Data> - Success
///
/// # Metadata
///
/// @tag category
#[rovo]
async fn handler() -> impl IntoApiResponse {
    Json(data)
}

Add OpenAPI setup in main():

use rovo::aide::openapi::OpenApi;

let mut api = OpenApi::default();
api.info.title = "My API".to_string();

let app = Router::new()
    .route("/path", get(handler))
    .with_oas(api)
    .with_swagger("/")
    .with_state(state);

Tips

Path Parameters

For primitive types (String, u64, Uuid, bool, etc.), document parameters directly in doc comments:

/// Get user by ID.
///
/// # Path Parameters
///
/// id: The user's unique identifier
///
/// # Responses
///
/// 200: Json<User> - User found
#[rovo]
async fn get_user(Path(id): Path<u64>) -> impl IntoApiResponse {
    // ...
}

For tuple parameters:

/// Get item in collection.
///
/// # Path Parameters
///
/// collection_id: The collection UUID
/// index: Item index
///
/// # Responses
///
/// 200: Json<Item> - Item found
#[rovo]
async fn get_item(Path((collection_id, index)): Path<(Uuid, u32)>) -> impl IntoApiResponse {
    // ...
}

For complex types, use structs with JsonSchema:

use rovo::schemars::JsonSchema;
use serde::Deserialize;
use uuid::Uuid;

#[derive(Deserialize, JsonSchema)]
struct UserId {
    /// The user's unique identifier
    id: Uuid,
}

#[rovo]
async fn get_user(Path(UserId { id }): Path<UserId>) -> impl IntoApiResponse {
    // ...
}

Security Schemes

Define in OpenAPI object:

use rovo::aide::openapi::{SecurityScheme, SecuritySchemeData};

api.components.get_or_insert_default()
    .security_schemes
    .insert(
        "bearer_auth".to_string(),
        SecurityScheme {
            data: SecuritySchemeData::Http {
                scheme: "bearer".to_string(),
                bearer_format: Some("JWT".to_string()),
            },
            ..Default::default()
        },
    );

Reference in handlers:

/// Protected endpoint requiring authentication.
///
/// # Responses
///
/// 200: Json<Data> - Success
/// 401: () - Unauthorized
///
/// # Metadata
///
/// @security bearer_auth
#[rovo]
async fn protected_handler() -> impl IntoApiResponse {
    // ...
}

Troubleshooting

Handler doesn't implement required traits

Add the #[rovo] macro:

#[rovo]
async fn handler() -> impl IntoApiResponse {
    // ...
}

Type mismatch with .with_state()

Add explicit type annotation:

let router: Router<()> = Router::<AppState>::new()
    .route("/path", get(handler))
    .with_state(state);

Comparison with aide

Feature	aide	rovo
Documentation	Separate _docs function	Doc comments
Routing	api_route()	Native axum syntax
Method chaining	Custom	Standard axum
Lines per endpoint	~15-20	~5-10

Development

This project uses just for common development tasks.

Quick Start

# List all available commands
just

# Run all checks (format, clippy, tests)
just check

# Fix formatting and clippy issues
just fix

# Run tests
just test

# Check for outdated dependencies
just outdated

# Check for unused dependencies
just unused-deps

# Check for security vulnerabilities
just audit

Pre-commit Hooks

Uses prek for git hooks:

prek install
prek run  # Run manually

Available Commands

• just test - Run all tests
• just lint - Run clippy lints
• just fmt - Format code
• just check - Run all checks (fmt, clippy, test)
• just fix - Run all checks and fixes
• just build - Build the project
• just example - Run the todo_api example
• just outdated - Check for outdated dependencies
• just unused-deps - Check for unused dependencies
• just audit - Check for security vulnerabilities
• just docs - Build and open documentation
• just pre-release - Run all pre-release checks

See just --list for all available commands.

Contributing

Contributions are welcome. Please submit a Pull Request.

License

MIT