g2h: gRPC to HTTP Bridge Generator

Seamlessly expose your gRPC services as HTTP/JSON endpoints using Axum

g2h (gRPC-to-HTTP) automatically generates Axum HTTP handlers for your gRPC services, allowing them to be consumed by both gRPC clients and traditional web clients using HTTP/JSON.

Features

• 🔄 Automatic conversion between gRPC and HTTP/JSON
• 🛣️ Creates Axum routes that match gRPC service methods
• 🔌 Works with existing Tonic services with zero modification
• 🧠 Preserves metadata and headers between protocols
• 🚦 Proper error status conversion from gRPC to HTTP

Quick Start

# Cargo.toml
[dependencies]
tonic = "0.13.0"
prost = "0.13.5"
axum = "0.7.0"
serde = { version = "1.0", features = ["derive"] }

[build-dependencies]
g2h = "0.1.0"
tonic-build = "0.13.0"
prost-build = "0.13.5"

// In your build.rs
use g2h::BridgeGenerator;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Simple approach with default settings
    BridgeGenerator::with_tonic_build()
        .build_prost_config()
        .compile_protos(&["proto/service.proto"], &["proto"])?;
    
    Ok(())
}

// In your main.rs - Create an Axum app with your gRPC service
let my_service = MyServiceImpl::default();
let http_router = my_service_handler(my_service);

let app = Router::new().nest("/api", http_router);

Now your service is accessible through both gRPC and HTTP:

POST /api/package.ServiceName/MethodName
Content-Type: application/json

{
  "field": "value"
}

Documentation

For complete usage examples and API documentation:

• Detailed Usage Guide
• Documentation
• Example Project

How It Works

g2h extends the standard gRPC code generation pipeline to create additional Axum router functions. These routers map HTTP POST requests to their corresponding gRPC methods, handling serialization/deserialization and status code conversion automatically.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.