GRPC for C# error to connect another API client

Question

I make a study about gRPC and when I will test the connection with the APIGRPC server with API simple client I have an error 404. I check the connections and I check the JSON file but I don't know where this problem is.

I use C# with visual studio 2019 I make the connection with the connection tool of visual studio

the proto file code

syntax = "proto3";

option csharp_namespace = "Discount.Grpc.Protos";

service DiscountProtoService {
    rpc GetDiscount (GetDiscountRequest) returns (CouponModel);

    rpc CreateDiscount (CreateDiscountRequest) returns (CouponModel);
    rpc UpdateDiscount (UpdateDiscountRequest) returns (CouponModel);
    rpc DeleteDiscount (DeleteDiscountRequest) returns (DeleteDiscountResponse);
}

message GetDiscountRequest {
    string productName = 1; 
}

message CouponModel {
    int32 id = 1;
    string productName = 2;
    string description = 3;
    int32 amount = 4;
}

message CreateDiscountRequest {
    CouponModel coupon = 1;
}

message UpdateDiscountRequest {
    CouponModel coupon = 1;
}

message DeleteDiscountRequest {
    string productName = 1;
}

message DeleteDiscountResponse {
    bool success = 1;
}

the JSON code of the client

   {
  "CacheSettings": {
    "ConnectionString": "localhost:6379"
  },
  "GrpcSettings": {
    "DiscountUrl": "http://localhost:5003"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*"
}

the JSON code of the GRPC server

{
  "DatabaseSettings": {
    "ConnectionString": "Server=localhost;Port=5432;Database=DiscountDb;User Id=admin;Password=admin1234;"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*",
  "Kestrel": {
    "EndpointDefaults": {
      "Protocols": "Http2"
    }
  }
}

and the response with error

Grpc.Core.RpcException: Status(StatusCode="Unimplemented", Detail="Bad gRPC response. HTTP status code: 404")
   at Basket.API.GrpcServices.DiscountGrpcService.GetDiscount(String productName) in C:\Users\Matheus\Documents\dir\microservicesASPnet\src\Services\Basket\Basket.API\GrpcServices\DiscountGrpcService.cs:line 21
   at Basket.API.Controllers.BasketController.UpdateBasket(ShoppingCart basket) in C:\Users\Matheus\Documents\dir\microservicesASPnet\src\Services\Basket\Basket.API\Controllers\BasketController.cs:line 41
   at lambda_method5(Closure , Object )
   at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.AwaitableObjectResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeActionMethodAsync>g__Awaited|12_0(ControllerActionInvoker invoker, ValueTask`1 actionResultValueTask)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeNextActionFilterAsync>g__Awaited|10_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeInnerFilterAsync>g__Awaited|13_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)
   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

API client XML .csproj

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>net5.0</TargetFramework>
    <DockerDefaultTargetOS>Linux</DockerDefaultTargetOS>
    <DockerfileContext>..\..\..</DockerfileContext>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Grpc.AspNetCore" Version="2.32.0" />
    <PackageReference Include="Microsoft.Extensions.Caching.StackExchangeRedis" Version="6.0.1" />
    <PackageReference Include="Microsoft.VisualStudio.Azure.Containers.Tools.Targets" Version="1.11.1" />
    <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
    <PackageReference Include="Swashbuckle.AspNetCore" Version="5.6.3" />
  </ItemGroup>

  <ItemGroup>
    <Protobuf Include="..\..\Discount\Discount.Grpc\Protos\discount.proto" GrpcServices="Client">
      <Link>Protos\discount.proto</Link>
    </Protobuf>
  </ItemGroup>

</Project>

API GRPC

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>net5.0</TargetFramework>
    <DockerComposeProjectPath>..\..\..\docker-compose.dcproj</DockerComposeProjectPath>
    <DockerDefaultTargetOS>Linux</DockerDefaultTargetOS>
    <DockerfileContext>..\..\..</DockerfileContext>
  </PropertyGroup>

  <ItemGroup>
    <None Remove="Protos\discount.proto" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="AutoMapper.Extensions.Microsoft.DependencyInjection" Version="8.1.1" />
    <PackageReference Include="Grpc.AspNetCore" Version="2.35.0" />
    <PackageReference Include="Dapper" Version="2.0.78" />
    <PackageReference Include="Microsoft.VisualStudio.Azure.Containers.Tools.Targets" Version="1.10.13" />
    <PackageReference Include="Npgsql" Version="5.0.3" />
  </ItemGroup>

  <ItemGroup>
    <Protobuf Include="Protos\discount.proto" GrpcServices="Server" />
  </ItemGroup>

</Project>

Answer 1

i solve the problem, my error is not the connection my error is from dependency injection in the startup class I don't put MapGrpcServer<>():

the code correct is

using Discount.Grpc.Repositories;
using Discount.Grpc.Services;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace Discount.Grpc
{
    public class Startup
    {
        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddScoped<IDiscountRepository, DiscountRepository>();
            services.AddAutoMapper(typeof(Startup));
            services.AddGrpc();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseRouting();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapGrpcService<DiscountService>();

                endpoints.MapGet("/", async context =>
                {
                    await context.Response.WriteAsync("Communication with gRPC endpoints must be made through a gRPC client. To learn how to create a client, visit: https://go.microsoft.com/fwlink/?linkid=2086909");
                });
            });
        }
    }
}