Always add event source logger (#287)

build/dependencies.props

@@ -25,6 +25,7 @@
     <MicrosoftExtensionsLoggingConfigurationPackageVersion>2.2.0-preview3-35425</MicrosoftExtensionsLoggingConfigurationPackageVersion>
     <MicrosoftExtensionsLoggingConsolePackageVersion>2.2.0-preview3-35425</MicrosoftExtensionsLoggingConsolePackageVersion>
     <MicrosoftExtensionsLoggingDebugPackageVersion>2.2.0-preview3-35425</MicrosoftExtensionsLoggingDebugPackageVersion>
+    <MicrosoftExtensionsLoggingEventSourcePackageVersion>2.2.0-preview3-35425</MicrosoftExtensionsLoggingEventSourcePackageVersion>
     <MicrosoftExtensionsLoggingPackageVersion>2.2.0-preview3-35425</MicrosoftExtensionsLoggingPackageVersion>
     <MicrosoftNETCoreApp20PackageVersion>2.0.9</MicrosoftNETCoreApp20PackageVersion>
     <MicrosoftNETCoreApp21PackageVersion>2.1.3</MicrosoftNETCoreApp21PackageVersion>

src/Microsoft.AspNetCore/Microsoft.AspNetCore.csproj

@@ -26,6 +26,7 @@
     <PackageReference Include="Microsoft.Extensions.Logging.Configuration" Version="$(MicrosoftExtensionsLoggingConfigurationPackageVersion)" PrivateAssets="None" />
     <PackageReference Include="Microsoft.Extensions.Logging.Console" Version="$(MicrosoftExtensionsLoggingConsolePackageVersion)" PrivateAssets="None" />
     <PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="$(MicrosoftExtensionsLoggingDebugPackageVersion)" PrivateAssets="None" />
+    <PackageReference Include="Microsoft.Extensions.Logging.EventSource" Version="$(MicrosoftExtensionsLoggingEventSourcePackageVersion)" PrivateAssets="None" />
   </ItemGroup>
 
 </Project>

src/Microsoft.AspNetCore/WebHost.cs

@@ -190,6 +190,7 @@ namespace Microsoft.AspNetCore
                     logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
                     logging.AddConsole();
                     logging.AddDebug();
+                    logging.AddEventSourceLogger();
                 })
                 .ConfigureServices((hostingContext, services) =>
                 {

test/Microsoft.AspNetCore.Tests/WebHostTests.cs

@@ -2,11 +2,16 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Diagnostics.Tracing;
+using System.Linq;
 using System.Threading;
 using Microsoft.AspNetCore.HostFiltering;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Xunit;
 
@@ -49,6 +54,54 @@ namespace Microsoft.AspNetCore.Tests
             Assert.Contains("NewHost", options.AllowedHosts);
         }
 
+        [Fact]
+        public void CreateDefaultBuilder_RegistersEventSourceLogger()
+        {
+            var listener = new TestEventListener();
+            var host = WebHost.CreateDefaultBuilder()
+                .Configure(_ => { })
+                .Build();
+
+            var logger = host.Services.GetRequiredService<ILogger<WebHostTests>>();
+            logger.LogInformation("Request starting");
+
+            var events = listener.EventData.ToArray();
+            Assert.Contains(events, args =>
+                args.EventSource.Name == "Microsoft-Extensions-Logging" &&
+                args.Payload.OfType<string>().Any(p => p.Contains("Request starting")));
+        }
+
+        private class TestEventListener : EventListener
+        {
+            private volatile bool _disposed;
+
+            private ConcurrentQueue<EventWrittenEventArgs> _events = new ConcurrentQueue<EventWrittenEventArgs>();
+
+            public IEnumerable<EventWrittenEventArgs> EventData => _events;
+
+            protected override void OnEventSourceCreated(EventSource eventSource)
+            {
+                if (eventSource.Name == "Microsoft-Extensions-Logging")
+                {
+                    EnableEvents(eventSource, EventLevel.Informational);
+                }
+            }
+
+            protected override void OnEventWritten(EventWrittenEventArgs eventData)
+            {
+                if (!_disposed)
+                {
+                    _events.Enqueue(eventData);
+                }
+            }
+
+            public override void Dispose()
+            {
+                _disposed = true;
+                base.Dispose();
+            }
+        }
+
         private class ReloadableMemorySource : IConfigurationSource
         {
             public IConfigurationProvider Build(IConfigurationBuilder builder)