0. Create a new ASP.NET Core project

1. Add dependency in csproj manually or using NuGet

<PackageReferenceInclude="NLog.Web.AspNetCore"Version="4.*" /><PackageReferenceInclude="NLog"Version="4.*" />

2. Create a nlog.config file.

<?xml version="1.0" encoding="utf-8" ?><nlogxmlns="http://www.nlog-project.org/schemas/NLog.xsd"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd">      autoReload="true"      throwConfigExceptions="true"      internalLogLevel="info"      internalLogFile="c:\temp\internal-nlog-AspNetCore3.txt"><!-- enable asp.net core layout renderers-->  <extensions>    <addassembly="NLog.Web.AspNetCore"/>  </extensions><!-- the targets to write to-->  <targets><!-- File Target for all log messages with basic details-->    <targetxsi:type="File"name="allfile"fileName="c:\temp\nlog-AspNetCore3-all-${shortdate}.log"layout="${longdate}|${event-properties:item=EventId_Id:whenEmpty=0}|${level:uppercase=true}|${logger}|${message} ${exception:format=tostring}" /><!-- File Target for own log messages with extra web details using some ASP.NET core renderers-->    <targetxsi:type="File"name="ownFile-web"fileName="c:\temp\nlog-AspNetCore3-own-${shortdate}.log"layout="${longdate}|${event-properties:item=EventId_Id:whenEmpty=0}|${level:uppercase=true}|${logger}|${message} ${exception:format=tostring}|url: ${aspnet-request-url}|action: ${aspnet-mvc-action}|" /><!--Console Target for hosting lifetime messages to improve Docker / Visual Studio startup detection-->    <targetxsi:type="Console"name="lifetimeConsole"layout="${MicrosoftConsoleLayout}" />  </targets><!-- rules to map from logger name to target-->  <rules><!--All logs, including from Microsoft-->    <loggername="*"minlevel="Trace"writeTo="allfile" /><!--Output hosting lifetime messages to console target for faster startup detection-->    <loggername="Microsoft.Hosting.Lifetime"minlevel="Info"writeTo="lifetimeConsole, ownFile-web"final="true" /><!--Skip non-critical Microsoft logs and so log only own logs-->    <loggername="Microsoft.*"maxlevel="Info"final="true" /><!-- BlackHole-->    <loggername="*"minlevel="Trace"writeTo="ownFile-web" />  </rules></nlog>

3. Enable copy to bin folder

  <ItemGroup>    <ContentUpdate="nlog.config"CopyToOutputDirectory="PreserveNewest" />  </ItemGroup>

4. Update program.cs

usingSystem;usingNLog.Web;usingMicrosoft.AspNetCore;usingMicrosoft.AspNetCore.Hosting;usingMicrosoft.Extensions.Logging;usingMicrosoft.Extensions.Hosting;publicstaticvoidMain(string[]args){// Early init of NLog to allow startup and exception logging, before host is builtvarlogger=NLog.LogManager.Setup().LoadConfigurationFromAppSettings().GetCurrentClassLogger();try{logger.Debug("init main");CreateHostBuilder(args).Build().Run();}catch(Exceptionexception){//NLog: catch setup errorslogger.Error(exception,"Stopped program because of exception");throw;}finally{// Ensure to flush and stop internal timers/threads before application-exit (Avoid segmentation fault on Linux)NLog.LogManager.Shutdown();}}publicstaticIHostBuilderCreateHostBuilder(string[]args)=>Host.CreateDefaultBuilder(args).ConfigureWebHostDefaults(webBuilder=>{webBuilder.UseStartup<Startup>();}).ConfigureLogging(logging=>{logging.ClearProviders();logging.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace);}).UseNLog();// NLog: Setup NLog for Dependency injection

5. Configure appsettings.json

{"Logging": {"LogLevel": {"Default":"Trace","Microsoft":"Warning","Microsoft.Hosting.Lifetime":"Information"    }  },"AllowedHosts":"*"}

6. Write logs

usingMicrosoft.Extensions.Logging;publicclassHomeController:Controller{privatereadonlyILogger<HomeController>_logger;publicHomeController(ILogger<HomeController>logger){_logger=logger;_logger.LogDebug(1,"NLog injected into HomeController");}publicIActionResultIndex(){_logger.LogInformation("Hello, this is the index!");returnView();}

7. Example Output

nlog-own-2019-10-14.log

2019-10-14 23:15:09.3898|0|DEBUG|ASP.NET_Core_3___VS2019.Program|init main |url: |action: |ASP.NET_Core_3___VS2019.Program.Main2019-10-14 23:15:11.3867|1|DEBUG|ASP.NET_Core_3___VS2019.Controllers.HomeController|NLog injected into HomeController |url: https://localhost/|action: Index|ASP.NET_Core_3___VS2019.Controllers.HomeController..ctor2019-10-14 23:15:11.3867|0|INFO|ASP.NET_Core_3___VS2019.Controllers.HomeController|Hello, this is the index! |url: https://localhost/|action: Index|ASP.NET_Core_3___VS2019.Controllers.HomeController.Index

nlog-all-2019-10-14.log

2019-10-14 23:15:09.3898|0|DEBUG|ASP.NET_Core_3___VS2019.Program|init main 2019-10-14 23:15:10.9142|0|INFO|Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager|User profile is available. Using 'C:\Users\Julian\AppData\Local\ASP.NET\DataProtection-Keys' as key repository and Windows DPAPI to encrypt keys at rest. 2019-10-14 23:15:11.2680|0|INFO|Microsoft.Hosting.Lifetime|Application started. Press Ctrl+C to shut down. 2019-10-14 23:15:11.2680|0|INFO|Microsoft.Hosting.Lifetime|Hosting environment: Development 2019-10-14 23:15:11.2680|0|INFO|Microsoft.Hosting.Lifetime|Content root path: D:\nlog\NLog.Web\examples\ASP.NET Core 3\ASP.NET Core 3 - VS2019 2019-10-14 23:15:11.3238|1|INFO|Microsoft.AspNetCore.Hosting.Diagnostics|Request starting HTTP/2.0 GET https://localhost:44318/   2019-10-14 23:15:11.3434|0|INFO|Microsoft.AspNetCore.Routing.EndpointMiddleware|Executing endpoint 'ASP.NET_Core_3___VS2019.Controllers.HomeController.Index (ASP.NET Core 3 - VS2019)' 2019-10-14 23:15:11.3867|3|INFO|Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker|Route matched with {action = "Index", controller = "Home"}. Executing controller action with signature Microsoft.AspNetCore.Mvc.IActionResult Index() on controller ASP.NET_Core_3___VS2019.Controllers.HomeController (ASP.NET Core 3 - VS2019). 2019-10-14 23:15:11.3867|1|DEBUG|ASP.NET_Core_3___VS2019.Controllers.HomeController|NLog injected into HomeController 2019-10-14 23:15:11.3867|0|INFO|ASP.NET_Core_3___VS2019.Controllers.HomeController|Hello, this is the index! 2019-10-14 23:15:11.4161|1|INFO|Microsoft.AspNetCore.Mvc.ViewFeatures.ViewResultExecutor|Executing ViewResult, running view Index. 2019-10-14 23:15:11.5831|4|INFO|Microsoft.AspNetCore.Mvc.ViewFeatures.ViewResultExecutor|Executed ViewResult - view Index executed in 167.626ms. 2019-10-14 23:15:11.5831|2|INFO|Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker|Executed action ASP.NET_Core_3___VS2019.Controllers.HomeController.Index (ASP.NET Core 3 - VS2019) in 196.6052ms 2019-10-14 23:15:11.5831|1|INFO|Microsoft.AspNetCore.Routing.EndpointMiddleware|Executed endpoint 'ASP.NET_Core_3___VS2019.Controllers.HomeController.Index (ASP.NET Core 3 - VS2019)' 2019-10-14 23:15:11.5910|2|INFO|Microsoft.AspNetCore.Hosting.Diagnostics|Request finished in 267.9366ms 200 text/html; charset=utf-8 2019-10-14 23:15:11.6171|1|INFO|Microsoft.AspNetCore.Hosting.Diagnostics|Request starting HTTP/2.0 GET https://localhost:44318/lib/jquery/dist/jquery.min.js   2019-10-14 23:15:11.6171|1|INFO|Microsoft.AspNetCore.Hosting.Diagnostics|Request starting HTTP/2.0 GET https://localhost:44318/css/site.css   2019-10-14 23:15:11.6171|1|INFO|Microsoft.AspNetCore.Hosting.Diagnostics|Request starting HTTP/2.0 GET https://localhost:44318/lib/bootstrap/dist/css/bootstrap.min.css   2019-10-14 23:15:11.6365|1|INFO|Microsoft.AspNetCore.Hosting.Diagnostics|Request starting HTTP/2.0 GET https://localhost:44318/lib/bootstrap/dist/js/bootstrap.bundle.min.js   2019-10-14 23:15:11.6365|1|INFO|Microsoft.AspNetCore.Hosting.Diagnostics|Request starting HTTP/2.0 GET https://localhost:44318/js/site.js?v=4q1jwFhaPaZgr8WAUSrux6hAuh0XDg9kPS3xIVq36I0   2019-10-14 23:15:11.6627|2|INFO|Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware|Sending file. Request path: '/js/site.js'. Physical path: 'D:\nlog\NLog.Web\examples\ASP.NET Core 3\ASP.NET Core 3 - VS2019\wwwroot\js\site.js' 2019-10-14 23:15:11.6627|2|INFO|Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware|Sending file. Request path: '/css/site.css'. Physical path: 'D:\nlog\NLog.Web\examples\ASP.NET Core 3\ASP.NET Core 3 - VS2019\wwwroot\css\site.css' 2019-10-14 23:15:11.6627|2|INFO|Microsoft.AspNetCore.Hosting.Diagnostics|Request finished in 28.7787ms 200 application/javascript 2019-10-14 23:15:11.6696|2|INFO|Microsoft.AspNetCore.Hosting.Diagnostics|Request finished in 52.4825ms 200 text/css 2019-10-14 23:15:11.6853|2|INFO|Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware|Sending file. Request path: '/lib/bootstrap/dist/js/bootstrap.bundle.min.js'. Physical path: 'D:\nlog\NLog.Web\examples\ASP.NET Core 3\ASP.NET Core 3 - VS2019\wwwroot\lib\bootstrap\dist\js\bootstrap.bundle.min.js' 2019-10-14 23:15:11.6853|2|INFO|Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware|Sending file. Request path: '/lib/bootstrap/dist/css/bootstrap.min.css'. Physical path: 'D:\nlog\NLog.Web\examples\ASP.NET Core 3\ASP.NET Core 3 - VS2019\wwwroot\lib\bootstrap\dist\css\bootstrap.min.css' 2019-10-14 23:15:11.6853|2|INFO|Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware|Sending file. Request path: '/lib/jquery/dist/jquery.min.js'. Physical path: 'D:\nlog\NLog.Web\examples\ASP.NET Core 3\ASP.NET Core 3 - VS2019\wwwroot\lib\jquery\dist\jquery.min.js' 2019-10-14 23:15:11.6853|2|INFO|Microsoft.AspNetCore.Hosting.Diagnostics|Request finished in 50.937400000000004ms 200 application/javascript 2019-10-14 23:15:11.6853|2|INFO|Microsoft.AspNetCore.Hosting.Diagnostics|Request finished in 70.65100000000001ms 200 text/css 2019-10-14 23:15:11.6853|2|INFO|Microsoft.AspNetCore.Hosting.Diagnostics|Request finished in 71.51610000000001ms 200 application/javascript

Configure NLog Targets for output