ASP.NET Core 8中NLog无法写入ApplicationInsightsTarget的问题

问题背景 #

在ASP.NET Core 8.0应用中遇到以下异常行为，该问题在.NET Framework 4.8中不存在：

相关配置 #

使用的相关NuGet包（原文提及有图示），当前采用nlog.development.config配置文件，内容如下：

<nlog xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <extensions>
    <add assembly="NLog.Web.AspNetCore"/>
    <add assembly="Seq.Client.NLog" />
    <add assembly="Microsoft.ApplicationInsights.NLogTarget" />
  </extensions>
  <targets>
    <target name="seq" xsi:type="Seq" serverUrl="http://localhost:5341" />
    <target name="aiTarget" xsi:type="ApplicationInsightsTarget" />
  </targets>
  <rules>
    <logger name="*" minlevel="Trace" writeTo="seq" />
    <logger name="*" minlevel="Info" writeTo="aiTarget" />
  </rules>
</nlog>

Main方法中的日志配置代码：

var appInsightsConnectionString = builder.Configuration["AppInsightsConnectionString"];
var appInsightsOptions = new ApplicationInsightsServiceOptions
{
    EnableAdaptiveSampling = false,
    ConnectionString = appInsightsConnectionString
};
builder.Services.AddApplicationInsightsTelemetry(appInsightsOptions);

var nlogConfigFile = builder.Environment.IsDevelopment() ? "nlog.development.config" : "nlog.config";
LogManager.Configuration = new NLog.Config.XmlLoggingConfiguration(nlogConfigFile);
builder.Services.AddLogging(loggingBuilder => { loggingBuilder.AddNLog(); });

具体问题 #

• 注入到ScheduleController的ILogger<ScheduleController>实例可同时写入seq和aiTarget，但通过LogManager.GetLogger("TraceLogger")获取的实例仅能写入seq，无法写入aiTarget。需修复此问题并保持与.NET Framework 4.8的向后兼容性。
• 开发环境中执行builder.Services.AddLogging(loggingBuilder => { loggingBuilder.AddNLog(); })时，为何加载nlog.config而非nlog.development.config？

内容的提问来源于stack exchange，提问作者eugen_nw