log4net遥测相关的应用研究

Question

我希望我们的分布式事件日志记录具有适当的相关性。对于我们的Web应用程序来说，这似乎是自动的。应用程序服务API中的相关日志示例：

然而，对于我们的其他（非ASP，非WebApp）服务，如果我们使用的是Log4Net，而App Insights附加的日志是不相关的。我尝试了以下说明：https://docs.microsoft.com/en-us/azure/azure-monitor/app/correlation

如有任何关于如何使用log4net实现这一点的帮助，我们将不胜感激。

干杯！

Answer 1

跨服务相关性ID大多通过头传播。当为Web应用程序启用AI时，它从传入的头中读取IDS/Context，然后用适当的IDS/Context更新传出的头。在服务内部，使用活动对象跟踪操作，发出的每一个遥测都将与该活动相关联，从而共享必要的相关ID。

在服务总线/事件集线器通信的情况下，在最近的版本中也支持传播（IDS/Context作为元数据传播）。

如果服务不是基于Web的，并且AI自动关联传播不起作用，您可能需要手动从某些元数据中获取传入的ID信息（如果存在的话），恢复/启动活动，用此活动启动AI操作。当遥测项目在该活动范围内生成时，它将获得适当的ID，并将成为总体跟踪的一部分。这样，如果遥测是从在AI操作上下文范围内执行的Log4net跟踪生成的，那么该遥测应该得到正确的ID。

从标头访问相关性的代码示例：

public class ApplicationInsightsMiddleware : OwinMiddleware
{
    // you may create a new TelemetryConfiguration instance, reuse one you already have
    // or fetch the instance created by Application Insights SDK.
    private readonly TelemetryConfiguration telemetryConfiguration = TelemetryConfiguration.CreateDefault();
    private readonly TelemetryClient telemetryClient = new TelemetryClient(telemetryConfiguration);

    public ApplicationInsightsMiddleware(OwinMiddleware next) : base(next) {}

    public override async Task Invoke(IOwinContext context)
    {
        // Let's create and start RequestTelemetry.
        var requestTelemetry = new RequestTelemetry
        {
            Name = $"{context.Request.Method} {context.Request.Uri.GetLeftPart(UriPartial.Path)}"
        };

        // If there is a Request-Id received from the upstream service, set the telemetry context accordingly.
        if (context.Request.Headers.ContainsKey("Request-Id"))
        {
            var requestId = context.Request.Headers.Get("Request-Id");
            // Get the operation ID from the Request-Id (if you follow the HTTP Protocol for Correlation).
            requestTelemetry.Context.Operation.Id = GetOperationId(requestId);
            requestTelemetry.Context.Operation.ParentId = requestId;
        }

        // StartOperation is a helper method that allows correlation of 
        // current operations with nested operations/telemetry
        // and initializes start time and duration on telemetry items.
        var operation = telemetryClient.StartOperation(requestTelemetry);

        // Process the request.
        try
        {
            await Next.Invoke(context);
        }
        catch (Exception e)
        {
            requestTelemetry.Success = false;
            telemetryClient.TrackException(e);
            throw;
        }
        finally
        {
            // Update status code and success as appropriate.
            if (context.Response != null)
            {
                requestTelemetry.ResponseCode = context.Response.StatusCode.ToString();
                requestTelemetry.Success = context.Response.StatusCode >= 200 && context.Response.StatusCode <= 299;
            }
            else
            {
                requestTelemetry.Success = false;
            }

            // Now it's time to stop the operation (and track telemetry).
            telemetryClient.StopOperation(operation);
        }
    }

    public static string GetOperationId(string id)
    {
        // Returns the root ID from the '|' to the first '.' if any.
        int rootEnd = id.IndexOf('.');
        if (rootEnd < 0)
            rootEnd = id.Length;

        int rootStart = id[0] == '|' ? 1 : 0;
        return id.Substring(rootStart, rootEnd - rootStart);
    }
}

用于单独跟踪手动相关操作的代码示例：

async Task BackgroundTask()
{
    var operation = telemetryClient.StartOperation<DependencyTelemetry>(taskName);
    operation.Telemetry.Type = "Background";
    try
    {
        int progress = 0;
        while (progress < 100)
        {
            // Process the task.
            telemetryClient.TrackTrace($"done {progress++}%");
        }
        // Update status code and success as appropriate.
    }
    catch (Exception e)
    {
        telemetryClient.TrackException(e);
        // Update status code and success as appropriate.
        throw;
    }
    finally
    {
        telemetryClient.StopOperation(operation);
    }
}

请注意Application Insights SDK的最新版本正在切换到W3C相关标准，因此头名和预期格式将根据W3C规范有所不同。