Set Log.Logger in the new UseSerilog() overload.

Author: GoldenCrystal

README.md

@@ -88,3 +88,42 @@ Tip: to see Serilog output in the Visual Studio output window when running under
 With _Serilog.AspNetCore_ installed and configured, you can write log messages directly through Serilog or any `ILogger` interface injected by ASP.NET. All loggers will use the same underlying implementation, levels, and destinations.
 
 **Tip:** change the minimum level for `Microsoft` to `Warning` and plug in this [custom logging middleware](https://github.com/datalust/serilog-middleware-example/blob/master/src/Datalust.SerilogMiddlewareExample/Diagnostics/SerilogMiddleware.cs) to clean up request logging output and record more context around errors and exceptions.
+
+### Alternative configuration
+
+You can chose to build the logger as part of the `WebHostBuilder` pipeline, and thus benefit from the application configuration.
+The following code shows an example of such a configuration:
+
+````csharp
+public class Program
+{
+    public static void Main(string[] args)
+    {
+        var host = new WebHostBuilder()
+            .UseKestrel()
+            .UseContentRoot(Directory.GetCurrentDirectory())
+            // Load the application configuration over the web host configuration.
+            .ConfigureAppConfiguration((hostingContext, configurationBuilder) =>
+            {
+                configurationBuilder
+                    .SetBasePath(hostingContext.HostingEnvironment.ContentRootPath)
+                    .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
+                    .AddJsonFile($"appsettings.{hostingContext.HostingEnvironment.EnvironmentName}.json", optional: true, reloadOnChange: true)
+                    .AddEnvironmentVariables();
+            })
+            // Configure Serilog to be used as the logger for the whole application.
+            .UseSerilog((hostingContext, loggerConfiguration) =>
+                loggerConfiguration.ReadFrom.Configuration(hostingContext.Configuration)
+                    .Enrich.FromLogContext()
+                    .WriteTo.Console()
+            )
+            .UseIISIntegration()
+            .UseStartup<Startup>()
+            .Build();
+
+        host.Run();
+    }
+}
+````
+
+With this code, the default behavior is to set the created `ILogger` as the default logger. `Log.Logger` can be used as usual to access the created logger.

samples/SimpleWebSampleV2/Controllers/ConfigurationController.cs

@@ -24,8 +24,6 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Serilog.AspNetCore", "src\S
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Serilog.AspNetCore.Tests", "test\Serilog.AspNetCore.Tests\Serilog.AspNetCore.Tests.csproj", "{AD51759B-CD58-473F-9620-0B0E56A123A1}"
 EndProject
-Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SimpleWebSampleV2", "samples\SimpleWebSampleV2\SimpleWebSampleV2.csproj", "{2711EC78-7F7D-440B-A8AB-BA3D32227667}"
-EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -44,10 +42,6 @@ Global
 		{AD51759B-CD58-473F-9620-0B0E56A123A1}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{AD51759B-CD58-473F-9620-0B0E56A123A1}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{AD51759B-CD58-473F-9620-0B0E56A123A1}.Release|Any CPU.Build.0 = Release|Any CPU
-		{2711EC78-7F7D-440B-A8AB-BA3D32227667}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{2711EC78-7F7D-440B-A8AB-BA3D32227667}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{2711EC78-7F7D-440B-A8AB-BA3D32227667}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{2711EC78-7F7D-440B-A8AB-BA3D32227667}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -56,7 +50,6 @@ Global
 		{69F9A0ED-7910-4F33-8919-28BB05376FBC} = {F2407211-6043-439C-8E06-3641634332E7}
 		{0549D23F-986B-4FB2-BACE-16FD7A7BC9EF} = {A1893BD1-333D-4DFE-A0F0-DDBB2FE526E0}
 		{AD51759B-CD58-473F-9620-0B0E56A123A1} = {E30F638E-BBBE-4AD1-93CE-48CC69CFEFE1}
-		{2711EC78-7F7D-440B-A8AB-BA3D32227667} = {F2407211-6043-439C-8E06-3641634332E7}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {811E61C5-3871-4633-AFAE-B35B619C8A10}

samples/SimpleWebSampleV2/Program.cs

@@ -38,27 +38,31 @@ public static IWebHostBuilder UseSerilog(this IWebHostBuilder builder, Serilog.I
         {
             if (builder == null) throw new ArgumentNullException(nameof(builder));
             builder.ConfigureServices(collection =>
-                collection.AddSingleton<ILoggerFactory>(new SerilogLoggerFactory(logger, dispose)));
+                collection.AddSingleton<ILoggerFactory>(services => new SerilogLoggerFactory(logger, dispose)));
             return builder;
         }
 
         /// <summary>Sets Serilog as the logging provider.</summary>
+        /// <remarks>
+        /// A <see cref="WebHostBuilderContext"/> is supplied so that configuration and hosting information can be used.
+        /// The logger will be shut down when application services are disposed.
+        /// </remarks>
         /// <param name="builder">The web host builder to configure.</param>
-        /// <param name="configureSerilog">The delegate for configuring the <see cref="LoggerConfiguration" /> that will be used to construct a <see cref="Logger" />.</param>
+        /// <param name="configureLogger">The delegate for configuring the <see cref="LoggerConfiguration" /> that will be used to construct a <see cref="Logger" />.</param>
+        /// <param name="preserveStaticLogger">Indicates whether to preserve the value of <see cref="Log.Logger"/>.</param>
         /// <returns>The web host builder.</returns>
-        public static IWebHostBuilder UseSerilog(this IWebHostBuilder builder, Action<WebHostBuilderContext, LoggerConfiguration> configureSerilog)
+        public static IWebHostBuilder UseSerilog(this IWebHostBuilder builder, Action<WebHostBuilderContext, LoggerConfiguration> configureLogger, bool preserveStaticLogger = false)
         {
             if (builder == null) throw new ArgumentNullException(nameof(builder));
-            if (configureSerilog == null) throw new ArgumentNullException(nameof(configureSerilog));
-            builder.ConfigureServices
-            (
-                (context, collection) =>
-                {
-                    var loggerConfiguration = new LoggerConfiguration();
-                    configureSerilog(context, loggerConfiguration);
-                    collection.AddSingleton<ILoggerFactory>(new SerilogLoggerFactory(loggerConfiguration.CreateLogger(), true));
-                }
-            );
+            if (configureLogger == null) throw new ArgumentNullException(nameof(configureLogger));
+            builder.ConfigureServices((context, collection) =>
+            {
+                var loggerConfiguration = new LoggerConfiguration();
+                configureLogger(context, loggerConfiguration);
+                var logger = loggerConfiguration.CreateLogger();
+                collection.AddSingleton<ILoggerFactory>(services => new SerilogLoggerFactory(logger, true));
+                if (!preserveStaticLogger) Log.Logger = logger;
+            });
             return builder;
         }
     }