FluentGrpc.Gateway

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An extension based on ASP.NET Core endpoint routing that allows you to call gRPC just like a JSON API.

Generate dynamic routes for each gRPC client through reflection and expression tree, and the JSON -> Protobuf -> JSON transformation is completed by this extension.

At the same time, a conversion from Protobuf to Swagger, the OpenAPI specification, is currently implemented.

Installation

dotnet add package FluentGrpc.Gateway

Features

• gRPC-Gateway：Call gRPC like JSON API, it's similar to gRPC-JSON-Transcoder of Envoy.
• gRPC-Swagger：Review and debug the gRPC interface with Swagger.

Basic Usage

Define gRPC via Protobuf

syntax = "proto3";

option csharp_namespace = "ExampleService";

package greet;

// The greeting service definition.
service Greeter {
  // Sends a greeting
  rpc SayHello (HelloRequest) returns (HelloReply);
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

// The response message containing the greetings.
message HelloReply {
  string message = 1;
}

Make sure that the project can generate code for both the gRPC client and the server, because the gRPC client will be used in the gateway.

<ItemGroup>
    <Protobuf Include="Protos\greet.proto" GrpcServices="Both" />
</ItemGroup>

For more details, see：GreetGrpc.

Configure gRPC gateway

Install FluentGrpc.Gateway via NuGet. There are two patterns to configure gRPC gateway：

Aggregation Pattern

Add the following configuration to the entry file Startup.cs:

public void ConfigureServices(IServiceCollection services)
{

    // ...
    services.AddGrpcGateway(Configuration);
}

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    // ...
    app.UseGrpcGateway();
}

Add the following configuration to the configuration file appsettings.json：

"GrpcGateway": {
    "BaseUrl": "https://lcoalhost:5001",
    "UrlPrefix": "api",
    "UpstreamInfos": [
      {
        "BaseUrl": "https://localhost:8001",
        "AssemblyName": "CalculateGrpc"
      },
      {
        "BaseUrl": "https://localhost:7001",
        "AssemblyName": "GreetGrpc"
      }
    ]
  }

Sidecar Pattern

Add the following configuration to the entry file Startup.cs:

public void ConfigureServices(IServiceCollection services)
{

    // ...
    services.AddGrpc();
    services.AddGrpcGateway("https://localhost:8001");
}

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    // ...
    app.UseGrpcGateway();
}

For more details, see：ExampleGateway.

Consume gRPC like JSON API

To view a API document based on Swagger, enter the address in your browser：https://localhost:5001//swagger/index.html.

For the SayHelloAsync() method of the gRPC Client Greeter.GreeterClient, the default route generated is: api/greet.Greeter/SayHello.

At this point, we just need to use Postman or curl to consume the interface. Enjoy :)

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