Register diagnostic services; includes ILogger now in registered services since there's little reason not to provide it

Author: nblumhardt

src/Serilog.Extensions.Hosting/Extensions/Hosting/DiagnosticContext.cs

@@ -22,15 +22,15 @@ namespace Serilog.Extensions.Hosting
     /// </summary>
     public class DiagnosticContext : IDiagnosticContext
     {
-        readonly ILogger _log;
+        readonly ILogger _logger;
 
         /// <summary>
         /// Construct a <see cref="DiagnosticContext"/>.
         /// </summary>
-        /// <param name="log">A logger for binding properties in the context, or <c>null</c> to use <see cref="Log.Logger"/>.</param>
-        public DiagnosticContext(ILogger log)
+        /// <param name="logger">A logger for binding properties in the context, or <c>null</c> to use <see cref="Log.Logger"/>.</param>
+        public DiagnosticContext(ILogger logger)
         {
-            _log = log;
+            _logger = logger;
         }
 
         /// <summary>
@@ -50,7 +50,7 @@ public void Add(string propertyName, object value, bool destructureObjects = fal
 
             var collector = AmbientDiagnosticContextCollector.Current;
             if (collector != null && 
-                (_log ?? Log.Logger).BindProperty(propertyName, value, destructureObjects, out var property))
+                (_logger ?? Log.Logger).BindProperty(propertyName, value, destructureObjects, out var property))
             {
                 collector.Add(property);
             }

src/Serilog.Extensions.Hosting/SerilogHostBuilderExtensions.cs

@@ -16,6 +16,7 @@
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.DependencyInjection;
+using Serilog.Extensions.Hosting;
 using Serilog.Extensions.Logging;
 
 namespace Serilog
@@ -64,11 +65,7 @@ public static IHostBuilder UseSerilog(
                     collection.AddSingleton<ILoggerFactory>(services => new SerilogLoggerFactory(logger, dispose));
                 }
 
-                if (logger != null)
-                {
-                    // This won't (and shouldn't) take ownership of the logger. 
-                    collection.AddSingleton(logger);
-                }
+                ConfigureServices(collection, logger);
             });
 
             return builder;
@@ -80,7 +77,7 @@ public static IHostBuilder UseSerilog(
         /// The logger will be shut down when application services are disposed.
         /// </remarks>
         /// <param name="builder">The host builder to configure.</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="configureLogger">The delegate for configuring the <see cref="LoggerConfiguration" /> that will be used to construct a <see cref="Microsoft.Extensions.Logging.Logger" />.</param>
         /// <param name="preserveStaticLogger">Indicates whether to preserve the value of <see cref="Log.Logger"/>.</param>
         /// <param name="writeToProviders">By default, Serilog does not write events to <see cref="ILoggerProvider"/>s registered through
         /// the Microsoft.Extensions.Logging API. Normally, equivalent Serilog sinks are used in place of providers. Specify
@@ -109,9 +106,6 @@ public static IHostBuilder UseSerilog(
                 configureLogger(context, loggerConfiguration);
                 var logger = loggerConfiguration.CreateLogger();
 
-                // This won't (and shouldn't) take ownership of the logger. 
-                collection.AddSingleton(logger);
-
                 ILogger registeredLogger = null;
                 if (preserveStaticLogger)
                 {
@@ -136,8 +130,30 @@ public static IHostBuilder UseSerilog(
 
                     return factory;
                 });
+
+                ConfigureServices(collection, logger);
             });
             return builder;
         }
+
+        static void ConfigureServices(IServiceCollection collection, ILogger logger)
+        {
+            if (collection == null) throw new ArgumentNullException(nameof(collection));
+
+            if (logger != null)
+            {
+                // This won't (and shouldn't) take ownership of the logger. 
+                collection.AddSingleton(logger);
+            }
+
+            // Registered to provide two services...
+            var diagnosticContext = new DiagnosticContext(logger);
+
+            // Consumed by e.g. middleware
+            collection.AddSingleton(diagnosticContext);
+
+            // Consumed by user code
+            collection.AddSingleton<IDiagnosticContext>(diagnosticContext);
+        }
     }
 }