Microsoft.Extensions.Logging.NLog

Version 3.1.1

Supports only Microsoft.AspNetCore.App 3.1.101-*

Version 3.0.0

Supports only Microsoft.AspNetCore.App 3.0.0-*

Version 2.2.0

Support SDK v.2.2.0

Version 2.1.0

Add support the feature turn on/off scope logging
Support SDK v.2.1.3

Microsoft.Extensions.Logging.NLog is an adapter between NLog and Microsoft.Extensions.Logging.

It allows to simplify using NLog by utilizing ILoggerFactory and ILogger interfaces in an application.

NLog is a flexible and free logging platform for various .NET platforms, including .NET standard. NLog makes it easy to write to several targets. (database, file, console) and change the logging configuration on-the-fly.

Nuget.org

Nuget package Microsoft.Extensions.Logging.NLog

Adding Microsoft.Extensions.Logging.NLog

You have to define two configurations:

Create the NLog configuration xml

<?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"
     autoReload="true"
     internalLogLevel="Warn"
     internalLogFile="c:\temp\internal-nlog.txt">

 <!-- https://github.com/NLog/NLog/wiki/Configuration-file  -->
 <targets>
   
   <!-- Null loggers -->
   
   <target xsi:type="Null" name="NullLog" />
   <target xsi:type="Null" name="SystemLog" />
   
   <!-- Console loggers -->
   <target xsi:type="Console" name="ConsoleInfoLog" />
   <target xsi:type="Console" name="ConsoleErrorLog" error="true" />


   <!-- File loggers -->

   <target xsi:type="File" name="CommonInfoLogFile"
           fileName="\Logs\RestWebApplication\Info\RestWebApp_CommonInfo-P_${processid}-${shortdate:universalTime=true}.log"
           layout="${longdate:universalTime=true}|${event-properties:item=EventId.Id}|${logger}|${uppercase:${level}}|${message}| ${exception}" />
   
   <target xsi:type="File" name="BusinessErrorLogFile"
           fileName="\Logs\RestWebApplication\BusinessError\RestWebApp_BusinessError-P_${processid}-${shortdate:universalTime=true}.log"
           layout="${longdate:universalTime=true}|${event-properties:item=EventId.Id}|${logger}|${uppercase:${level}}|${message}| ${exception}" />

   <target xsi:type="File" name="FatalErrorLogFile"
           fileName="\Logs\RestWebApplication\Error\RestWebApp_FatalError-P_${processid}-${shortdate:universalTime=true}.log"
           layout="${longdate:universalTime=true}|${event-properties:item=EventId.Id}|${logger}|${uppercase:${level}}|${message}| ${exception:innerFormat=Message,Method,StackTrace:maxInnerExceptionLevel=1:format=Message,Method,StackTrace}" />
 
 </targets>

 <rules>
   <!-- Loggers application section -->

   <logger name="FatalError" writeTo="FatalErrorLogFile,CommonInfoLogFile" minlevel="Error"  final="true" enabled="true" />
   <logger name="BusinessError" writeTo="BusinessErrorLogFile,CommonInfoLogFile" minlevel="Error"  final="true" enabled="true" />

   <logger name="CommonInfo" writeTo="CommonInfoLogFile"               minlevel="Info"   final="true" enabled="true" />
   
   <logger name="ConsoleError" writeTo="ConsoleErrorLog,FatalErrorLogFile,CommonInfoLogFile" minlevel="Error"  final="true" enabled="true" />
   <logger name="ConsoleInfo" writeTo="ConsoleInfoLog,CommonInfoLogFile"  minlevel="Info"   final="true" enabled="true" />

   <!-- Other log info -->
   <logger name="Microsoft*"      minlevel="Trace" writeTo="SystemLog"      final="true" enabled="false" />
   <!-- discard all not consumed -->
   <logger name="*" minlevel="Trace" writeTo="NullLog" />
 </rules>

</nlog>

Create NLogLoggerSettings configuration section in "appsettings.json".

The NLogLoggerSettings section defines the Category Name "filter" and Category Name "mapper".

{
"NLogLoggerSettings": {

    "IncludeScopes": true,

    "AcceptedCategoryNames": [ /* Filter of category name */
      "ConsoleInfo",   /* The category name is accepted as a "NLog logger name" */
      "CommonInfo",    /* The category name is accepted as a "NLog logger name" */
      "ConsoleError",  /* The category name is accepted as a "NLog logger name" */
      "FatalError",    /* The category name is accepted as a "NLog logger name" */
      "BusinessError", /* The category name is accepted as a "NLog logger name" */
      "*Error*",       /* The category name that contains "Error" is accepted as a "NLog logger name" */
      "*Info",         /* The category name that ends with "Info" is accepted as a "NLog logger name" */
      "Com*",          /* The category name that starts with "Com" is accepted as a "NLog logger name" */
      "*"              /* Any category name will be accepted  as a "NLog logger name" */
    ],

    /* Map category name "ABC" to "NLog logger name" = "ConsoleError" */
    "AcceptedAliasesCategoryNames:ABD": "ConsoleError"  
    
    /* Map category name that ends with "*Hosted" to "NLog logger name" = "ConsoleError" */
    "AcceptedAliasesCategoryNames:*Hosted": "ConsoleError"  

    /* Map category name that starts with "Microsoft.AspNetCore*" to "NLog logger name" = "ConsoleError" */
    "AcceptedAliasesCategoryNames:Microsoft.AspNetCore*": "ConsoleError" 

    /* Map category name that contains "*AspNetCore*" to "NLog logger name" = "ConsoleError"*/
    "AcceptedAliasesCategoryNames:*AspNetCore*": "ConsoleError"

    /* Map any category  to "NLog logger name" = "ConsoleError" */
    "AcceptedAliasesCategoryNames:*": "ConsoleError"

  }
}

The AcceptedCategoryNames - "category name filter" is used to filter-in category names. It is expected that the category name is exact match to <logger name="...." in the NLog xml configuration.
The AcceptedAliasesCategoryNames - "category name mapper" is used to filter-in category names and map them onto new name that expected to be match to <logger name="..." in the NLog xml configuration.

Web Host Builder configuration

After defining the configurations, add in the Web Host Builder configuring of Microsoft.Extensions.Logging.LoggerFactory the following initialization code:

     .ConfigureLogging((hostingContext, logging) =>
       {

        // ** Add Microsoft.Extensions.Logging.NLog

        string logPath = Path.Combine(hostingContext.HostingEnvironment.ContentRootPath, $"nlog.{hostingContext.HostingEnvironment.EnvironmentName}.config");
        if (!File.Exists(logPath))
        {
            throw new MissingMemberException($"Missing NLog configuration file '{logPath}'");
        }
        var nLoggingConfiguration = new XmlLoggingConfiguration(logPath);

        var logJsonCgf = hostingContext.Configuration.GetSection(nameof(NLogLoggerSettings));
        if (!logJsonCgf.Exists())
        {
            throw new MissingMemberException($"Missing configuration section '{nameof(NLogLoggerSettings)}'");
        }

        logging.AddNLogLogger(logJsonCgf, nLoggingConfiguration);
      }

Example projects

See sample of pure NLog style project Using Adaptation NLog in .Net Core Rest Web Application

See sample of pure .Net Core Logger => NLog style project Using Logger + NLog in .Net Core Rest Web Application

Microsoft.Extensions.Logging - Configuration

If you decided to use additional filtering from Microsoft.Extensions.Logging over the filtering that provided with Microsoft.Extensions.Logging.NLog by adding configuration:

 logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));

So, It is recommend to read "how to configure the Logging'" section from ASP.NET CORE web guide https://docs.microsoft.com/en-us/aspnet/core/fundamentals/logging/?view=aspnetcore-3.0#configuration.

Wallsmedia / Logging.NLog