使用HTTP Debugger时调用AccessSecretVersion出现gRPC异常求助

问题场景 #

使用HTTP Debugger工具时，Google Cloud Secret Manager的AccessSecretVersion调用会抛出Grpc.Core.RpcException，提示无法建立HTTP/2连接；不使用该工具时代码运行正常。临时方案是在调用后启动调试器，但操作繁琐，需要彻底解决。

异常信息 #

Grpc.Core.RpcException
  HResult=0x80131500
  Message=Status(StatusCode="Internal", Detail="Error starting gRPC call. HttpRequestException: Requesting HTTP version 2.0 with version policy RequestVersionOrHigher while unable to establish HTTP/2 connection.", DebugException="System.Net.Http.HttpRequestException: Requesting HTTP version 2.0 with version policy RequestVersionOrHigher while unable to establish HTTP/2 connection.")
  Source=Grpc.Net.Client
  StackTrace:
   at Grpc.Net.Client.Internal.GrpcCall`2.<GetResponseHeadersCoreAsync>d__72.MoveNext()
   at Grpc.Net.Client.Internal.HttpClientCallInvoker.BlockingUnaryCall[TRequest,TResponse](Method`2 method, String host, CallOptions options, TRequest request)
   at Grpc.Core.Interceptors.InterceptingCallInvoker.<BlockingUnaryCall>b__3_0[TRequest,TResponse](TRequest req, ClientInterceptorContext`2 ctx)
   at Grpc.Core.ClientBase.ClientBaseConfiguration.ClientBaseConfigurationInterceptor.BlockingUnaryCall[TRequest,TResponse](TRequest request, ClientInterceptorContext`2 context, BlockingUnaryCallContinuation`2 continuation)
   at Grpc.Core.Interceptors.InterceptingCallInvoker.BlockingUnaryCall[TRequest,TResponse](Method`2 method, String host, CallOptions options, TRequest request)
   at Google.Cloud.SecretManager.V1.SecretManagerService.SecretManagerServiceClient.AccessSecretVersion(AccessSecretVersionRequest request, CallOptions options)
   at Google.Api.Gax.Grpc.ApiCall.GrpcCallAdapter`2.CallSync(TRequest request, CallSettings callSettings)
   at Google.Api.Gax.Grpc.ApiCallRetryExtensions.<>c__DisplayClass1_0`2.<WithRetry>b__0(TRequest request, CallSettings callSettings)
   at ....

  This exception was originally thrown at this call stack:
    [External Code]

Inner Exception 1:
HttpRequestException: Requesting HTTP version 2.0 with version policy RequestVersionOrHigher while unable to establish HTTP/2 connection.

问题根源 #

gRPC默认使用HTTP/2协议，但HTTP Debugger工具可能不支持或无法正确拦截HTTP/2流量，导致客户端无法建立有效连接，进而触发异常。解决思路是强制gRPC客户端使用HTTP/1.1协议。

具体解决方案 #

通过自定义HttpClient并配置HTTP版本为1.1，再将其传入SecretManagerServiceClient的构建器，替代默认的客户端创建逻辑。修改后的完整代码如下：

public class SecretManagerService
{
    private readonly SecretManagerServiceClient _client;
    private readonly string _projectId;     
    private readonly string _secretName;     

    public SecretManagerService(string projectId, string secretName)
    {
        // 自定义HttpClientHandler，配置代理并适配调试工具
        var httpHandler = new HttpClientHandler
        {
            Proxy = new WebProxy(),
            UseProxy = true
        };

        // 创建强制使用HTTP/1.1的HttpClient
        var httpClient = new HttpClient(httpHandler)
        {
            DefaultRequestVersion = HttpVersion.Version11,
            DefaultVersionPolicy = HttpVersionPolicy.RequestVersionExact
        };

        // 通过构建器注入自定义HttpClient，创建SecretManager客户端
        _client = new SecretManagerServiceClientBuilder
        {
            HttpClient = httpClient
        }.Build();

        _projectId = projectId; 
        _secretName = secretName;
    }                   
    
    public string GetSecretValue()
    {
        var secretVersionName = new SecretVersionName(_projectId, _secretName, "latest");
        var secret = _client.AccessSecretVersion(secretVersionName);
        return secret.Payload.Data.ToStringUtf8();
    }            

    public void UpdateSecretValue(string newValue)
    {
        var secretName = new SecretName(_projectId, _secretName);

        var updatedPayload = new SecretPayload
        {
            Data = Google.Protobuf.ByteString.CopyFromUtf8(newValue)
        };

        try
        {
            _client.AddSecretVersion(secretName, updatedPayload);
        }
        catch
        {
            Console.WriteLine("    Error updating secret");
        }
    }            
}

关键修改点说明 #

1. 替代全局代理设置：将原HttpClient.DefaultProxy的全局配置移至自定义HttpClientHandler内部，避免影响其他HttpClient实例，同时保证代理配置生效。
2. 强制HTTP/1.1：通过DefaultRequestVersion指定使用HTTP/1.1，DefaultVersionPolicy设为RequestVersionExact确保客户端不会尝试升级到HTTP/2。
3. 客户端构建器注入：使用SecretManagerServiceClientBuilder替代默认的Create()方法，将自定义HttpClient传入，让gRPC调用完全遵循指定的HTTP协议规则。

验证 #

修改后启动HTTP Debugger工具，再次调用GetSecretValue方法，应能正常获取Secret值，不再抛出HTTP/2连接相关异常。

内容的提问来源于stack exchange，提问作者Hneel