在带有.Net Core 2.2的Linux上遇到错误“ System.Net.Sockets.SocketException：连接被拒绝”

Question

在执行一些集成测试用例时，我在Linux OS上遇到.Net Core 2.2的问题。这是堆栈跟踪：

  

失败的mytest（）错误消息：System.Net.WebException：失败   5次重试后----> System.Net.WebException：连接被拒绝   连接被拒绝----> System.Net.Http.HttpRequestException：   连接被拒绝----> System.Net.Sockets.SocketException：   连接被拒绝堆栈跟踪：WebApiClient.cs：第56行
  WebApiClient.cs：第34行位于   PdsWebAppTests.ClientForTestPdsWebApp.Call（方法，字符串url，   字符串requestContent，WebClientHeaders标头）   ClientForTestPdsWebApp.cs：第19行，位于   IntegrationTests.IntegrationTests 1.mytest() in IntegrationTests.cs:line 44 --WebException at System.Net.HttpWebRequest.GetResponse() at WebApiClient.GetResponse(WebRequest webRequest) in WebApiClient.cs:line 117 at WebApiClient.ReceiveResponse(WebRequest webRequest) in WebApiClient.cs:line 97 CallWithRetries(Method method, String uriString, String requestContent, WebClientHeaders headers, Int32 retryCount) in WebApiClient.cs:line 46 --HttpRequestException at System.Net.Http.ConnectHelper.ConnectAsync(String host, Int32 port, CancellationToken cancellationToken) at System.Threading.Tasks.ValueTask 1.get_Result（）位于   System.Net.Http.HttpConnectionPool.CreateConnectionAsync（HttpRequestMessage   的请求，在   System.Threading.Tasks.ValueTask 1.get_Result() at System.Net.Http.HttpConnectionPool.WaitForCreatedConnectionAsync(ValueTask 1   位于System.Threading.Tasks.ValueTask 1.get_Result()
at System.Net.Http.HttpConnectionPool.SendWithRetryAsync(HttpRequestMessage request, Boolean doRequestAuth, CancellationToken cancellationToken)
at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) at System.Net.Http.HttpClient.FinishSendAsyncUnbuffered(Task 1 sendTask上的creationTask），   HttpRequestMessage请求，CancellationTokenSource cts，布尔值   DisposeCts）位于System.Net.HttpWebRequest.SendRequest（）处   System.Net.HttpWebRequest.GetResponse（）   System.Net.Http.ConnectHelper.ConnectAsync上的--SocketException（字符串主机，Int32端口，   CancellationToken cancellingToken）

这是我的高级代码流：

public Response Call(Method method, string uriString, WebClientHeaders headers, string requestContent)
{
    var response = CallWithRetries(method, uriString, requestContent, headers, NumberOfTimesToRetry); //WebApiClient.cs:line 34
    return response;
}

private Response CallWithRetries(Method method, string uriString, string requestContent, WebClientHeaders headers, int retryCount)
{
    var lastException = new WebException();
    for (var retriesLeft = retryCount; retriesLeft > 0; --retriesLeft)
    {
        try
        {
            var webRequest = CreateRequest(method, uriString, requestContent, headers);
            var response = ReceiveResponse(webRequest);
            return response;
        }
        catch (WebException e)
        {
            lastException = e;
        }
        Thread.Sleep(RetryBackoffPeriod);
    }
    throw new WebException($"Failed after {retryCount} retries", lastException);
}

private Response ReceiveResponse(WebRequest webRequest)
{
    var json = "no json returned :-(";
    var webResponse = GetResponse(webRequest); //at WebApiClient.ReceiveResponse(WebRequest webRequest) in WebApiClient.cs:line 97
    if (webResponse == null) return null;
    using (webResponse)
    {
        var responseStream = webResponse.GetResponseStream();
        if (responseStream != null)
        {
            using (var y = new StreamReader(responseStream))
            {
                json = y.ReadToEnd();
            }
        }
        return new Response(((HttpWebResponse)webResponse).StatusCode, json);
    }
}

P.S。 该测试用例在Windows中运行良好。同样从Linux机器上，我能够启动Web应用程序并执行所有操作，所以我认为只是WebRequest.GetResponse()引发了异常。