Added layout render for ASP.NET Core Connection.Id

Add TryGetConnection to HttpContextExtensions and update layout renders that use connection to use that instead.

src/NLog.Web.AspNetCore/LayoutRenderers/AspNetRequestConnectionIdLayoutRenderer.cs

@@ -0,0 +1,36 @@
+using NLog.LayoutRenderers;
+using NLog.Web.Internal;
+using System.Text;
+
+namespace NLog.Web.LayoutRenderers
+{
+    /// <summary>
+    /// ASP.NET request connection id
+    /// </summary>
+    /// <remarks>
+    /// ${aspnet-request-connection-id}
+    /// </remarks>
+    [LayoutRenderer("aspnet-request-connection-id")]
+    public class AspNetRequestConnectionIdLayoutRenderer : AspNetLayoutRendererBase
+    {
+        /// <summary>
+        /// Renders the ASP.NET connection ID
+        /// </summary>
+        /// <param name="builder">The <see cref="StringBuilder" /> to append the rendered data to.</param>
+        /// <param name="logEvent">Logging event.</param>
+        protected override void DoAppend(StringBuilder builder, LogEventInfo logEvent)
+        {
+            var connection = HttpContextAccessor.HttpContext.TryGetConnection();
+            if (connection == null)
+            {
+                return;
+            }
+
+            var id = connection.Id;
+            if(!string.IsNullOrEmpty(id))
+            {
+                builder.Append(id);
+            }
+        }
+    }
+}

src/Shared/Internal/HttpContextExtensions.cs

@@ -46,6 +46,14 @@ internal static HttpResponseBase TryGetResponse(this HttpContextBase context)
             }
         }
 #else
+        internal static ConnectionInfo TryGetConnection(this HttpContext context)
+        {
+            var connection = context?.Connection;
+            if (connection == null)
+                InternalLogger.Debug("HttpContext Connection Lookup returned null");
+            return connection;
+        }
+
         internal static HttpRequest TryGetRequest(this HttpContext context)
         {
             var request = context?.Request;

src/Shared/LayoutRenderers/AspNetRequestLocalIpLayoutRenderer.cs

@@ -26,7 +26,7 @@ protected override void DoAppend(StringBuilder builder, LogEventInfo logEvent)
             var httpContext = HttpContextAccessor.HttpContext;
 
 #if ASP_NET_CORE
-            var connection = httpContext.Connection;
+            var connection = httpContext.TryGetConnection();
             if (connection == null)
             {
                 return;

src/Shared/LayoutRenderers/AspNetRequestLocalPortLayoutRenderer.cs

@@ -25,7 +25,7 @@ protected override void DoAppend(StringBuilder builder, LogEventInfo logEvent)
         {
             var httpContext = HttpContextAccessor.HttpContext;
 #if ASP_NET_CORE
-            var connection = httpContext.Connection;
+            var connection = httpContext.TryGetConnection();
             if (connection == null)
             {
                 return;

src/Shared/LayoutRenderers/AspNetRequestRemotePortLayoutRenderer.cs

@@ -26,7 +26,7 @@ protected override void DoAppend(StringBuilder builder, LogEventInfo logEvent)
             var httpContext = HttpContextAccessor.HttpContext;
 
 #if ASP_NET_CORE
-            var connection = httpContext.Connection;
+            var connection = httpContext.TryGetConnection();
             if (connection == null)
             {
                 return;

tests/NLog.Web.AspNetCore.Tests/LayoutRenderers/AspNetRequestConnectionIdLayoutRendererTests.cs

@@ -0,0 +1,52 @@
+using NLog.Web.LayoutRenderers;
+using NSubstitute;
+using NSubstitute.ReturnsExtensions;
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Xunit;
+
+namespace NLog.Web.Tests.LayoutRenderers
+{
+    public class AspNetRequestConnectionIdLayoutRendererTests : LayoutRenderersTestBase<AspNetRequestConnectionIdLayoutRenderer>
+    {
+        [Fact]
+        public void SuccessTest()
+        {
+            // Arrange
+            var (renderer, httpContext) = CreateWithHttpContext();
+
+            httpContext.Connection.Id.Returns("My Connection Id");
+            // Act
+            string result = renderer.Render(new LogEventInfo());
+            // Assert
+            Assert.Equal("My Connection Id", result);
+        }
+
+        [Fact]
+        public void EmptyTest()
+        {
+            // Arrange
+            var (renderer, httpContext) = CreateWithHttpContext();
+
+            httpContext.Connection.Id.Returns("");
+            // Act
+            string result = renderer.Render(new LogEventInfo());
+            // Assert
+            Assert.Equal("", result);
+        }
+
+        [Fact]
+        public void NullTest()
+        {
+            // Arrange
+            var (renderer, httpContext) = CreateWithHttpContext();
+
+            httpContext.Connection.Id.ReturnsNull();
+            // Act
+            string result = renderer.Render(new LogEventInfo());
+            // Assert
+            Assert.Equal("", result);
+        }
+    }
+}