调用外部时出现 SocketException api

Question

我正在使用自定义 class "ApiProvider"

从 Azure Function ServiceBusTrigger 调用我的 API

public class ApiProvider
{
    private readonly string _backendUrl;
    private static HttpClient _client;
    private readonly TraceWriter _log;

    public ApiProvider(TraceWriter log)
    {
        _pamUrl = Environment.GetEnvironmentVariable("ApiUrl");
        _log = log;
        _client = CreateHttpClient();
    }
}

我为 ServiceBus 队列中发送的每条消息调用它，假设有 1500 条消息，它将调用我支持的 1500 次。

有些调用是成功的，但有时我在 Azure Functions 日志中出错，没有太多信息！但根据 Application Insights：

System.Net.Sockets.SocketException
Exception while executing function: QueueDirectory An error occurred while sending the request. Unable to connect to the remote server Only one usage of each socket address (protocol/network address/port) is normally permitted

我认为将 HttpClient 设为静态就足够了，但它似乎并没有完全解决我猜想的问题，还是我遗漏了什么？

环境： Azure Functions 运行时：1.0.11702.0

编辑：我的方法 CreateHttpClient():

    private static HttpClient CreateHttpClient()
    {
        string thumbprint = Environment.GetEnvironmentVariable("WEBSITE_LOAD_CERTIFICATES");
        if (thumbprint != null)
        {
            _log.LogInformation("Get the certificate of thumbprint : " + thumbprint);

            using (X509Store certStore = new X509Store(StoreName.My, StoreLocation.CurrentUser))
            {
                certStore.Open(OpenFlags.ReadOnly);
                X509Certificate2Collection certCollection =
                    certStore.Certificates.Find(X509FindType.FindByThumbprint, thumbprint, false);

                // Get the first cert with the thumbprint
                var certificate = certCollection.OfType<X509Certificate2>().FirstOrDefault();
                if (certificate != null)
                {
                    _log.LogInformation("Certificate has been found.");
                    var handler = new WebRequestHandler();
                    handler.ClientCertificates.Add(certCollection[0]);
                    return new HttpClient(handler);
                }
                _log.LogInformation("Certificate has not been found.");
            }
        }
        return new HttpClient();
    }

Answer 1

您应该只创建一次 HttpClient，而不是为每个请求创建一次：

private static HttpClient _client = new HttpClient();

或者如果您需要保留初始化：

public class ApiProvider
{
    private readonly string _backendUrl;
    private static HttpClient _client;
    private readonly TraceWriter _log;

    static ApiProvider()
    {
        _client = CreateHttpClient();
    }

    public ApiProvider(TraceWriter log)
    {
        _pamUrl = Environment.GetEnvironmentVariable("ApiUrl");
        _log = log;
    }
}

更新：

根据您的修改，我建议：

从 CreateHttpClient 中删除 _log 用法，如果您遇到证书加载问题，则抛出异常。这应该允许保持此方法静态，并且如果设置出现问题，也会快速且明显地失败。
如果您确实需要 CreateHttpClient 中的记录器，请将其设为非静态并使用您的原始代码，但只调用 CreateHttpClient 一次：
```
public ApiProvider(TraceWriter log)
{
    _pamUrl = Environment.GetEnvironmentVariable("ApiUrl");
    _log = log;
    if (_client == null) _client = CreateHttpClient();
}
```
可能存在一些竞争条件，但我认为这不是什么大问题。如果需要，请加锁。

调用外部时出现 SocketException api

SocketException when calling external api

servicebus

azure-functions