Align with suggested approach

Signed-off-by: Tom Kerkhove <kerkhove.tom@gmail.com>

Author: tomkerkhove

README.md

@@ -162,12 +162,23 @@ This pattern has the advantage of reducing the number of log events that need to
 The following request information will be added as log properties:
 
 * `RequestMethod`
-* `RequestScheme`
-* `RequestHost`
 * `RequestPath`
 * `StatusCode`
 * `Elapsed`
 
+Not enough? You can extend the information that is being emitted by using `options.EnrichDiagnosticContext`:
+
+```csharp
+app.UseSerilogRequestLogging(options =>
+{
+    options.EnrichDiagnosticContext = (diagnosticContext, httpContext) =>
+    {
+        diagnosticContext.Set("RequestHost", httpContext.Request.Host.Value);
+        diagnosticContext.Set("RequestScheme", httpContext.Request.Scheme);
+    };
+});
+```
+
 ### Inline initialization
 
 You can alternatively configure Serilog inline, in `BuildWebHost()`, using a delegate as shown below:

samples/EarlyInitializationSample/Startup.cs

@@ -30,8 +30,15 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
             // Write streamlined request completion events, instead of the more verbose ones from the framework.
             // To use the default framework request logging instead, remove this line and set the "Microsoft"
             // level in appsettings.json to "Information".
-            app.UseSerilogRequestLogging();
-
+            app.UseSerilogRequestLogging(options =>
+            {
+                options.EnrichDiagnosticContext = (diagnosticContext, httpContext) =>
+                {
+                    diagnosticContext.Set("RequestHost", httpContext.Request.Host.Value);
+                    diagnosticContext.Set("RequestScheme", httpContext.Request.Scheme);
+                };
+            });
+            
             app.UseRouting();
 
             app.UseEndpoints(endpoints =>

samples/InlineInitializationSample/Startup.cs

@@ -32,7 +32,14 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
             // Write streamlined request completion events, instead of the more verbose ones from the framework.
             // To use the default framework request logging instead, remove this line and set the "Microsoft"
             // level in appsettings.json to "Information".
-            app.UseSerilogRequestLogging();
+            app.UseSerilogRequestLogging(options =>
+            {
+                options.EnrichDiagnosticContext = (diagnosticContext, httpContext) =>
+                {
+                    diagnosticContext.Set("RequestHost", httpContext.Request.Host.Value);
+                    diagnosticContext.Set("RequestScheme", httpContext.Request.Scheme);
+                };
+            });
 
             app.UseRouting();
 

src/Serilog.AspNetCore/AspNetCore/RequestLoggingMiddleware.cs

@@ -29,6 +29,7 @@ class RequestLoggingMiddleware
         readonly RequestDelegate _next;
         readonly DiagnosticContext _diagnosticContext;
         readonly MessageTemplate _messageTemplate;
+        readonly Action<IDiagnosticContext, HttpContext> _enrichDiagnosticContext;
         readonly Func<HttpContext, double, Exception, LogEventLevel> _getLevel;
         static readonly LogEventProperty[] NoProperties = new LogEventProperty[0];
 
@@ -39,6 +40,7 @@ public RequestLoggingMiddleware(RequestDelegate next, DiagnosticContext diagnost
             _diagnosticContext = diagnosticContext ?? throw new ArgumentNullException(nameof(diagnosticContext));
 
             _getLevel = options.GetLevel;
+            _enrichDiagnosticContext = options.EnrichDiagnosticContext;
             _messageTemplate = new MessageTemplateParser().Parse(options.MessageTemplate);
         }
 
@@ -78,13 +80,14 @@ bool LogCompletion(HttpContext httpContext, DiagnosticContextCollector collector
 
             if (!collector.TryComplete(out var collectedProperties))
                 collectedProperties = NoProperties;
-            
+
+            // Enrich diagnostic context
+            _enrichDiagnosticContext?.Invoke(_diagnosticContext, httpContext);
+
             // Last-in (correctly) wins...
             var properties = collectedProperties.Concat(new[]
             {
                 new LogEventProperty("RequestMethod", new ScalarValue(httpContext.Request.Method)),
-                new LogEventProperty("RequestHost", new ScalarValue(httpContext.Request.Host.Value)),
-                new LogEventProperty("RequestScheme", new ScalarValue(httpContext.Request.Scheme)),
                 new LogEventProperty("RequestPath", new ScalarValue(GetPath(httpContext))),
                 new LogEventProperty("StatusCode", new ScalarValue(statusCode)),
                 new LogEventProperty("Elapsed", new ScalarValue(elapsedMs))

src/Serilog.AspNetCore/AspNetCore/RequestLoggingOptions.cs

@@ -45,6 +45,11 @@ public class RequestLoggingOptions
         /// </value>
         public Func<HttpContext, double, Exception, LogEventLevel> GetLevel { get; set; }
 
+        /// <summary>
+        /// Gets or sets the action that allows you to enrich the diagnostic context
+        /// </summary>
+        public Action<IDiagnosticContext, HttpContext> EnrichDiagnosticContext { get; set; }
+
         internal RequestLoggingOptions() { }
     }
 }