swagger not working with gRPC .net core 7 - asp.net-core

Question

I followed the steps this documentation https://learn.microsoft.com/en-us/aspnet/core/grpc/json-transcoding-openapi?view=aspnetcore-7.0 and integrated google protos.
I tried to open it locally and adding /swagger/index.html
and I am getting
An HTTP/1.x request was sent to an HTTP/2 only endpoint.
Program.cs:
using Extensions;
using Google.Api;
using gRPCserver.Services;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Caching.Memory;
using Microsoft.OpenApi.Models;
using Models.Models;
using Serilog;
using Serilog.Sinks.Kafka;
using sKashCallCenterAPI.Interface;
using sKashCallCenterAPI.Service;
var builder = WebApplication.CreateBuilder(args);
var ConnectionString = builder.Configuration["sqlconnection:ConnectionString"];
builder.Services.AddDbContext<sKashDbContext>(options =>
{
options.UseSqlServer(ConnectionString);
});
//builder.Services.AddGrpc();
builder.Services.AddGrpcSwagger();
builder.Services.AddGrpcHttpApi();
builder.Services.AddSwaggerGen(c =>
{
c.SwaggerDoc("v1",
new OpenApiInfo { Title = "gRPC Server", Version = "v1" });
var filePath = Path.Combine(System.AppContext.BaseDirectory, "gRPCserver.xml");
c.IncludeXmlComments(filePath);
c.IncludeGrpcXmlComments(filePath, includeControllerXmlComments: true);
});
ConfigurationManager configuration = builder.Configuration;
var kafkaServer = configuration["KafkaConfig:ServerIP"] + ":" + configuration["KafkaConfig:Port"];
builder.Host.UseSerilog((ctx, lc) => lc
.WriteTo.Console()
.WriteTo.Kafka(topic: configuration["KafkaConfig:Topic"], bootstrapServers: kafkaServer)
.Enrich.WithProperty("Source", configuration["KafkaConfig:Source"])
.ReadFrom.Configuration(ctx.Configuration));
builder.Services.ConfigurJWTAuthentication();
builder.Services.ConfigureRepositoryWrapper();
builder.Services.ConfigureContractsServices();
builder.Services.AddScoped<IAuthService, AuthService>();
builder.Services.AddScoped<IMemoryCache, MemoryCache>();
var app = builder.Build();
app.UseSwagger();
app.UseSwaggerUI(c =>
{
c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");
});
app.UseRouting();
// Configure the HTTP request pipeline.
//app.MapGrpcService<GreeterService>();
app.UseEndpoints(endpoints =>
{
endpoints.MapGrpcService<GreeterService>();
});
app.MapGet("/", () => "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");
app.Run();
The project is running but no swagger documentation is shown.

Answer 1

Assuming you're debugging using Kestrel, did you configure its protocol support for both HTTP1 and HTTP2 in appsettings or the startup pipeline?
{
"Kestrel": {
"EndpointDefaults": {
"Protocols": "Http1AndHttp2"
}
}
}

Answer 2

Yes, you are right. The swagger documentation will not show up as default. You will have to use a plugin as grpc-gateway. This is a reverse-proxy server which translates a RESTful HTTP API into gRPC, by reading protobuf service definitions.