C# gRPC localhost - 启动 gRPC 调用时出错：不知道这样的主机

Question

I'm trying to get Microsoft's gRPC "Greeter" application to work on my business laptop, but I keep getting the following exception when invoking the gRPC call:

Grpc.Core.RpcException: 'Status(StatusCode=Internal, Detail="Error starting gRPC call: No such host is known.")'

This is the documentation from Microsoft, which I followed. The exact code I'm running comes from Microsoft's samples and can be found on their github here .

It literally boils down to starting the most basic gRPC server and then invoking the call via

using var channel = GrpcChannel.ForAddress("https://localhost:5001");
var client =  new Greeter.GreeterClient(channel);
var reply = await client.SayHelloAsync(new HelloRequest { Name = "GreeterClient" });

The call to SayHelloAsync is the one that throws the exception. The exact same code on my home machine works fine. I've already checked my /etc/hosts file for weird entries, but nothing. I've also tried changing https://localhost:5001 to https://[::1]:5001 and https://127.0.0.1:5001 , same exception, which I find incredibly weird.

I've also already tried http via AppContext.SetSwitch("System.Net.Http.SocketsHttpHandler.Http2UnencryptedSupport", true); and calling the http endpoint, same exception.

Answer 1

I figured it out. As expected it was a problem with the networking setup of my work laptop.

I had the HTTP_PROXY and HTTPS_PROXY environment variables set. These were picked up by the underlying HttpClient and tried routing the requests through the proxy. Removing the HTTP_PROXY and HTTPS_PROXY environment variables fixed the problem. Alternatively setting the NO_PROXY environment variable to localhost,127.0.0.1,::1 also fixed the problem.