azure - 使用 nlog.config 在 Azure Function Log Streams 中进行 NLog

Question

我的问题与此非常相似:How can I get NLog output to appear in the streaming logs for an Azure Function? 。在该问题中，接受的答案显示了如何在函数调用开始时配置 nlog。我想通过 nlog.config 文件进行配置，或者至少在设置时仅配置一次，而不是每次调用该函数时都配置一次。

使用下面的代码，我在 Application Insight 日志中看到 NLog 消息，但在日志流中看不到。我希望从 NLog 记录的消息也显示在日志流中。

函数代码

    private static readonly Logger _logger = NLog.LogManager.GetCurrentClassLogger();

    [FunctionName("TestLog")]
    public static async Task<IActionResult> TestLog([HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)]
                                                HttpRequest req, ILogger log)
    {
        //shows in both Application Insights and Log Stream.
        log.LogInformation("Log From ILogger");

        //shows in Application Insights but not in Log Stream.
        _logger.Info("Log From NLog");

        return new OkObjectResult("OK");
    }

函数启动

    [assembly: FunctionsStartup(typeof(MyNamespace.TestFunctionApp.Startup))]
    
    namespace MyNamespace.TestFunctionApp
    {            
        public class Startup : FunctionsStartup
        {            
            public override void Configure(IFunctionsHostBuilder builder)
            {
                //nLog file ends 1 directory up from bins when deployed
                var binDirectory = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
                var rootDirectory = Path.GetFullPath(Path.Combine(binDirectory, ".."));
                var nLogConfigPath = Path.Combine(rootDirectory, "NLog.config");
        
                //create MicrosoftILoggerTarget (I think this has to be done from code since it needs a ref to an ILogger instance).  But this does not seem to work.
                var loggerFactory = new Microsoft.Extensions.Logging.LoggerFactory();
                var azureILogger = loggerFactory.CreateLogger("NLog");
                var loggerTarget = new NLog.Extensions.Logging.MicrosoftILoggerTarget(azureILogger);
        
                //setup NLog
                LogManager.Setup()
                          .SetupExtensions(e => e.AutoLoadAssemblies(false))
                          .LoadConfigurationFromFile(nLogConfigPath, optional: false)
                          .LoadConfiguration(builder => builder.Configuration.AddRuleForAllLevels(loggerTarget));            
             }
        }
   }

NLog.config

<?xml version="1.0" encoding="utf-8"?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <extensions>
    <add assembly="Microsoft.ApplicationInsights.NLogTarget" />
  </extensions>
  <targets>
    <target name="a" xsi:type="ApplicationInsightsTarget"/>
  </targets>
  <rules>
    <logger name="*" minlevel="Info" writeTo="a" />
  </rules>
</nlog>

Answer 1

通常目标是让 Microsoft ILogger 的输出达到 NLog 目标。这是通过调用 UseNLog() 或 AddNLog() 来完成的，这会将 NLog 添加为 LoggingProvider。

替代方案有一个已使用 NLog 的现有库，但希望将输出重定向到 Microsoft ILoggerFactory。但如果还想添加 NLog 作为 LoggingProvider，则必须小心，因为这是循环/递归的噩梦。

但我想您可以执行以下操作将所有输出从 NLog 重定向到 Microsoft ILoggerFactory:

    public class Startup : FunctionsStartup
    {            
        public override void Configure(IFunctionsHostBuilder builder)
        {
            var serviceProvider = builder.Services.BuildServiceProvider();
            var executionContextOptions = serviceProvider.GetService<IOptions<ExecutionContextOptions>>().Value;
            var appDirectory = executionContextOptions.AppDirectory;

            var loggerFactory = serviceProvider.GetService<ILoggerFactory>();
                          
            // Setup NLog redirect all logevents to Microsoft ILoggerFactory
            var nlogLoggerName = "NLog";
            var nlogLogger = loggerFactory.CreateLogger(nlogLoggerName);
            var nlogTarget = new NLog.Extensions.Logging.MicrosoftILoggerTarget(nlogLogger);
            var nLogConfigPath = Path.Combine(appDirectory, "NLog.config");
    
            //setup NLog
            LogManager.Setup()
                      .SetupExtensions(e => e.AutoLoadAssemblies(false))
                      .LoadConfigurationFromFile(nLogConfigPath, optional: false)
                      .LoadConfiguration(builder => {
                          // Ignore output from logger named "NLog" to avoid recursion
                          builder.Configuration.Rules.Add(new LoggingRule() { LoggerNamePattern = nlogLoggerName, MaxLevel = LogLevel.Off, Final = true });
                          builder.Configuration.AddRuleForAllLevels(loggerTarget));
                      });
         }
    }