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Serilog logging for ASP.NET Core. This package routes ASP.NET Core log messages through Serilog, so you can get information about ASP.NET's internal operations written to the same Serilog sinks as your application events.

WithSerilog.AspNetCore installed and configured, you can write log messages directly through Serilog or anyILogger interface injected by ASP.NET. All loggers will use the same underlying implementation, levels, and destinations.

Versioning: This package tracks the versioning and target framework support of itsMicrosoft.Extensions.Hosting dependency. Most users should choose the version ofSerilog.AspNetCore that matchestheir application's target framework. I.e. if you're targeting .NET 7.x, choose a 7.x version ofSerilog.AspNetCore. Ifyou're targeting .NET 8.x, choose an 8.xSerilog.AspNetCore version, and so on.

First, install theSerilog.AspNetCoreNuGet package into your app.

dotnet add package Serilog.AspNetCore

Next, in your application'sProgram.cs file, configure Serilog first. Atry/catch block will ensure any configuration issues are appropriately logged:

usingSerilog;Log.Logger=newLoggerConfiguration().WriteTo.Console().CreateLogger();try{Log.Information("Starting web application");varbuilder=WebApplication.CreateBuilder(args);builder.Services.AddSerilog();// <-- Add this linevarapp=builder.Build();app.MapGet("/",()=>"Hello World!");app.Run();}catch(Exceptionex){Log.Fatal(ex,"Application terminated unexpectedly");}finally{Log.CloseAndFlush();}

Thebuilder.Services.AddSerilog() call will redirect all log events through your Serilog pipeline.

Finally, clean up by removing the remaining configuration for the default logger, including the"Logging" section fromappsettings.*.json files (this can be replaced withSerilog configuration as shown intheSample project, if required).

That's it! With the level bumped up a little you will see log output resembling:

[12:01:43 INF] Starting web application[12:01:44 INF] Now listening on: http://localhost:5000[12:01:44 INF] Application started. Press Ctrl+C to shut down.[12:01:44 INF] Hosting environment: Development[12:01:44 INF] Content root path: serilog-aspnetcore/samples/Sample[12:01:47 WRN] Failed to determine the https port for redirect.[12:01:47 INF] Hello, world![12:01:47 INF] HTTP GET / responded 200 in 95.0581 ms

Tip: to see Serilog output in the Visual Studio output window when running under IIS, either selectASP.NET Core Web Server from theShow output from drop-down list, or replaceWriteTo.Console() in the logger configuration withWriteTo.Debug().

A more complete example, includingappsettings.json configuration, can be found inthe sample project here.

The package includes middleware for smarter HTTP request logging. The default request logging implemented by ASP.NET Core is noisy, with multiple events emitted per request. The included middleware condenses these into a single event that carries method, path, status code, and timing information.

As text, this has a format like:

[16:05:54 INF] HTTP GET / responded 200 in 227.3253 ms

Oras JSON:

{"@t":"2019-06-26T06:05:54.6881162Z","@mt":"HTTP {RequestMethod} {RequestPath} responded {StatusCode} in {Elapsed:0.0000} ms","@r": ["224.5185"],"RequestMethod":"GET","RequestPath":"/","StatusCode":200,"Elapsed":224.5185,"RequestId":"0HLNPVG1HI42T:00000001","CorrelationId":null,"ConnectionId":"0HLNPVG1HI42T"}

To enable the middleware, first change the minimum level for the noisy ASP.NET Core log sources toWarning in your logger configuration orappsettings.json file:

.MinimumLevel.Override("Microsoft.AspNetCore.Hosting",LogEventLevel.Warning).MinimumLevel.Override("Microsoft.AspNetCore.Mvc",LogEventLevel.Warning).MinimumLevel.Override("Microsoft.AspNetCore.Routing",LogEventLevel.Warning)

Tip: add{SourceContext} to your console logger's output template to see the names of loggers; this can help track down the source of a noisy log event to suppress.

Then, in your application'sProgram.cs, add the middleware withUseSerilogRequestLogging():

varapp=builder.Build();app.UseSerilogRequestLogging();// <-- Add this line// Other app configuration

It's important that theUseSerilogRequestLogging() call appearsbefore handlers such as MVC. The middleware will not time or log components that appear before it in the pipeline. (This can be utilized to exclude noisy handlers from logging, such asUseStaticFiles(), by placingUseSerilogRequestLogging() after them.)

During request processing, additional properties can be attached to the completion event usingIDiagnosticContext.Set():

publicclassHomeController:Controller{readonlyIDiagnosticContext_diagnosticContext;publicHomeController(IDiagnosticContextdiagnosticContext){_diagnosticContext=diagnosticContext??thrownewArgumentNullException(nameof(diagnosticContext));}publicIActionResultIndex(){// The request completion event will carry this property_diagnosticContext.Set("CatalogLoadTime",1423);returnView();}

This pattern has the advantage of reducing the number of log events that need to be constructed, transmitted, and stored per HTTP request. Having many properties on the same event can also make correlation of request details and other data easier.

The following request information will be added as properties by default:

• RequestMethod
• RequestPath
• StatusCode
• Elapsed

You can modify the message template used for request completion events, add additional properties, or change the event level, using theoptions callback onUseSerilogRequestLogging():

app.UseSerilogRequestLogging(options=>{// Customize the message templateoptions.MessageTemplate="Handled {RequestPath}";// Emit debug-level events instead of the defaultsoptions.GetLevel=(httpContext,elapsed,ex)=>LogEventLevel.Debug;// Attach additional properties to the request completion eventoptions.EnrichDiagnosticContext=(diagnosticContext,httpContext)=>{diagnosticContext.Set("RequestHost",httpContext.Request.Host.Value);diagnosticContext.Set("RequestScheme",httpContext.Request.Scheme);};});

The example at the top of this page shows how to configure Serilog immediately when the application starts. This has the benefit of catching and reporting exceptions thrown during set-up of the ASP.NET Core host.

The downside of initializing Serilog first is that services from the ASP.NET Core host, including theappsettings.json configuration and dependency injection, aren't available yet.

To address this, Serilog supports two-stage initialization. An initial "bootstrap" logger is configured immediately when the program starts, and this is replaced by the fully-configured logger once the host has loaded.

To use this technique, first replace the initialCreateLogger() call withCreateBootstrapLogger():

usingSerilog;usingSerilog.Events;Log.Logger=newLoggerConfiguration().MinimumLevel.Override("Microsoft",LogEventLevel.Information).Enrich.FromLogContext().WriteTo.Console().CreateBootstrapLogger();// <-- Change this line!

Then, pass a callback toAddSerilog() that creates the final logger:

builder.Services.AddSerilog((services,lc)=>lc.ReadFrom.Configuration(builder.Configuration).ReadFrom.Services(services).Enrich.FromLogContext().WriteTo.Console());

It's important to note that the final loggercompletely replaces the bootstrap logger: if you want both to log to the console, for instance, you'll need to specifyWriteTo.Console() in both places, as the example shows.

Using two-stage initialization, insert theReadFrom.Configuration(builder.Configuration) call shown in the example above. The JSON configuration syntax is documented intheSerilog.Settings.Configuration README.

Using two-stage initialization, insert theReadFrom.Services(services) call shown in the example above. TheReadFrom.Services() call will configure the logging pipeline with any registered implementations of the following services:

• IDestructuringPolicy
• ILogEventEnricher
• ILogEventFilter
• ILogEventSink
• LoggingLevelSwitch

TheConsole(),Debug(), andFile() sinks all support JSON-formatted output natively, via the includedSerilog.Formatting.Compact package.

To write newline-delimited JSON, pass aCompactJsonFormatter orRenderedCompactJsonFormatter to the sink configuration method:

.WriteTo.Console(newRenderedCompactJsonFormatter())

The Azure Diagnostic Log Stream ships events from any files in theD:\home\LogFiles\ folder. To enable this for your app, add a file sink to yourLoggerConfiguration, taking care to set theshared andflushToDiskInterval parameters:

Log.Logger=newLoggerConfiguration().MinimumLevel.Debug().MinimumLevel.Override("Microsoft",LogEventLevel.Information).Enrich.FromLogContext().WriteTo.Console()// Add this line:.WriteTo.File(System.IO.Path.Combine(Environment.GetEnvironmentVariable("HOME"),"LogFiles","Application","diagnostics.txt"),rollingInterval:RollingInterval.Day,fileSizeLimitBytes:10*1024*1024,retainedFileCountLimit:2,rollOnFileSizeLimit:true,shared:true,flushToDiskInterval:TimeSpan.FromSeconds(1)).CreateLogger();

If you want to add extra properties to all log events in a specific part of your code, you can add them to theILogger<T> inMicrosoft.Extensions.Logging with the following code. For this code to work, make sure you have added the.Enrich.FromLogContext() to the.UseSerilog(...) statement, as specified in the samples above.

// Microsoft.Extensions.Logging ILogger<T>// Yes, it's required to use a dictionary. See https://nblumhardt.com/2016/11/ilogger-beginscope/using(logger.BeginScope(newDictionary<string,object>{["UserId"]="svrooij",["OperationType"]="update",})){// UserId and OperationType are set for all logging events in these brackets}

The code above results in the same outcome as if you would push properties in theLogContext in Serilog. More details can be found inhttps://github.com/serilog/serilog/wiki/Enrichment#the-logcontext.

// Serilog LogContextusing(LogContext.PushProperty("UserId","svrooij"))using(LogContext.PushProperty("OperationType","update")){// UserId and OperationType are set for all logging events in these brackets}