grpc-proxy

A gRPC proxy implementation that allows proxying gRPC requests through HTTP/JSON rules using Spring Cloud Gateway.

Overview

This project provides a proxy solution for gRPC services that:

• Converts gRPC requests/responses to JSON format
• Uses Spring Cloud Gateway for routing and filtering
• Supports dynamic service discovery through gRPC reflection
• Allows configuration via HTTP routing rules

Project Structure

• reflection-extension: gRPC reflection support for service discovery
• spring-cloud-gateway: Core proxy implementation using Spring Cloud Gateway
• examples:
  • example-server: Sample gRPC server implementation
  • example-spring-cloud-gateway: Example proxy configuration

Key Features

• Protocol Translation: Seamlessly converts between gRPC and JSON formats
• HTTP-based Routing: Define routing rules using familiar HTTP patterns
• Service Discovery: Automatic service and method discovery via gRPC reflection

Getting Started

See the examples directory for sample implementations showing how to:

• Set up a gRPC server
• Configure the proxy using Spring Cloud Gateway
• Define routing rules for JSON/gRPC translation

Dependencies

JitPack Repository

Add the JitPack repository to your build file:

repositories {
    maven { url "https://jitpack.io" }
}

Reflection Extension

implementation 'com.github.protobuf-x.grpc-proxy:reflection-extension:${release-version}'

Spring Cloud Gateway Extension

implementation 'com.github.protobuf-x.grpc-proxy:spring-cloud-gateway:${release-version}'

Requirements for Using Reflection Extension

• Your gRPC server must have reflection service enabled
• Server must be accessible from the proxy
• Protocol buffers must be properly configured in your project

Requirements for Using Spring Cloud Gateway

• Spring Cloud Gateway dependencies must be properly configured
• Your application must be configured as a Spring Boot application

Configuration

Enabling gRPC Reflection in Your Server

Server server = ServerBuilder.forPort(9090)
    .addService(new YourServiceImpl())
    .addService(ReflectionExtensionService.newInstance()) // Add this line
    .build();

Basic Spring Cloud Gateway Configuration

You can configure the gateway either through Java configuration or YAML configuration.

Java Configuration

@SpringBootApplication
public class ExampleGateway {
    @Bean
    RouteLocator routeLocator(RouteLocatorBuilder builder, GatewayFilter httpRuleJsonToGrpcGatewayFilter) {
        return builder.routes()
                .route("json-to-grpc", r -> r
                        .path("/example.echo.v1.EchoService/**")
                        .filters(f -> f.filter(httpRuleJsonToGrpcGatewayFilter))
                        .uri("http://localhost:6565")
                ).build();
    }

    @Bean
    GatewayFilter httpRuleJsonToGrpcGatewayFilter(ChannelRepository channelRepository,
                                                  ProtobufRepository protobufRepository) {
        return new HttpRuleJsonToGrpcGatewayFilterFactory(channelRepository, protobufRepository)
                .apply(new HttpRuleJsonToGrpcGatewayFilterFactory.Config());
    }

    @Bean
    ProtobufRepository protoRepository(ChannelRepository channelRepository) {
        return new CacheableServerProtobufRepository(channelRepository, 60);
    }

    @Bean
    ChannelRepository channelRepository() {
        return new InmemoryChannelRepository();
    }
}

For more detailed configuration examples, please refer to the examples directory.

License

This project is licensed under the MIT License