Get transaction name from Web API controller route template

.ci/windows/msbuild-tools.ps1

@@ -3,12 +3,12 @@
 #
 
 # Install visualstudio2019buildtools
-choco install visualstudio2019buildtools -m -y --no-progress --force -r --version=16.8.5.0
+choco install visualstudio2019buildtools -m -y --no-progress --force -r --version=16.9.0.0
 if ($LASTEXITCODE -ne 0) {
   Write-Host "visualstudio2019buildtools installation failed."
   exit 1
 }
-choco install visualstudio2019professional -m -y --no-progress --force -r --version=16.8.5.0 --package-parameters "--includeRecommended --includeOptional"
+choco install visualstudio2019professional -m -y --no-progress --force -r --version=16.9.0.0 --package-parameters "--includeRecommended --includeOptional"
 if ($LASTEXITCODE -ne 0) {
   Write-Host "visualstudio2019professional installation failed."
   exit 1

sample/AspNetFullFrameworkSampleApp/AspNetFullFrameworkSampleApp.csproj

@@ -142,6 +142,7 @@
     <Compile Include="Mvc\JsonBadRequestResult.cs" />
     <Compile Include="Mvc\JsonNetValueProviderFactory.cs" />
     <Compile Include="Mvc\StreamResult.cs" />
+    <Compile Include="Controllers\AttributeRoutingWebApiController.cs" />
   </ItemGroup>
   <ItemGroup Condition="'$(OS)' == 'WINDOWS_NT'">
     <Content Include="Content\bootstrap-grid.css" />

sample/AspNetFullFrameworkSampleApp/Controllers/AttributeRoutingWebApiController.cs

@@ -0,0 +1,21 @@
+// Licensed to Elasticsearch B.V under
+// one or more agreements.
+// Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information
+
+using System.Web.Http;
+
+namespace AspNetFullFrameworkSampleApp.Controllers
+{
+	[RoutePrefix(RoutePrefix)]
+	public class AttributeRoutingWebApiController : ApiController
+	{
+		public const string RoutePrefix = "api/AttributeRoutingWebApi";
+		public const string Route = "{id}";
+
+		[HttpGet]
+		[Route(Route)]
+		public IHttpActionResult Get(string id) =>
+			Ok($"attributed routed web api controller {id}");
+	}
+}

src/Elastic.Apm.AspNetFullFramework/ElasticApmModule.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information
 
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Specialized;
 using System.Linq;
@@ -15,6 +16,7 @@
 using Elastic.Apm.Helpers;
 using Elastic.Apm.Logging;
 using Elastic.Apm.Model;
+using Elastic.Apm.Reflection;
 
 namespace Elastic.Apm.AspNetFullFramework
 {
@@ -30,6 +32,8 @@ public class ElasticApmModule : IHttpModule
 		private readonly string _dbgInstanceName;
 		private HttpApplication _application;
 		private IApmLogger _logger;
+		private Type _httpRouteDataInterfaceType;
+		private Func<object, string> _routeDataTemplateGetter;
 
 		public ElasticApmModule() =>
 			// ReSharper disable once ImpureMethodCallOnReadonlyValueField
@@ -77,6 +81,7 @@ private void InitImpl(HttpApplication application)
 						PlatformDetection.DotNetRuntimeDescription, HttpRuntime.IISVersion);
 			}
 
+			_routeDataTemplateGetter = CreateWebApiAttributeRouteTemplateGetter();
 			_application = application;
 			_application.BeginRequest += OnBeginRequest;
 			_application.EndRequest += OnEndRequest;
@@ -285,8 +290,31 @@ private void ProcessEndRequest(object sender)
 						else
 							routeData = values;
 
-						_logger?.Trace()?.Log("Calculating transaction name based on route data");
-						var name = Transaction.GetNameFromRouteContext(routeData);
+						string name = null;
+
+						// if we're dealing with Web API attribute routing, get transaction name from the route template
+						if (routeData.TryGetValue("MS_SubRoutes", out var template) && _httpRouteDataInterfaceType != null)
+						{
+							if (template is IEnumerable enumerable)
+							{
+								var enumerator = enumerable.GetEnumerator();
+								if (enumerator.MoveNext())
+								{
+									var subRoute = enumerator.Current;
+									if (subRoute != null && _httpRouteDataInterfaceType.IsInstanceOfType(subRoute))
+									{
+										_logger?.Trace()?.Log("Calculating transaction name from web api attribute routing");
+										name = _routeDataTemplateGetter(subRoute);
+									}
+								}
+							}
+						}
+						else
+						{
+							_logger?.Trace()?.Log("Calculating transaction name based on route data");
+							name = Transaction.GetNameFromRouteContext(routeData);
+						}
+
 						if (!string.IsNullOrWhiteSpace(name)) transaction.Name = $"{context.Request.HttpMethod} {name}";
 					}
 					else
@@ -427,5 +455,37 @@ private static void SafeAgentSetup(string dbgInstanceName)
 				agentComponents.Dispose();
 			}
 		}
+
+		/// <summary>
+		/// Compiles a delegate from a lambda expression to get the route template from HttpRouteData when
+		/// System.Web.Http is referenced.
+		/// </summary>
+		private Func<object, string> CreateWebApiAttributeRouteTemplateGetter()
+		{
+			_httpRouteDataInterfaceType = Type.GetType("System.Web.Http.Routing.IHttpRouteData,System.Web.Http");
+			if (_httpRouteDataInterfaceType != null)
+			{
+				var routePropertyInfo = _httpRouteDataInterfaceType.GetProperty("Route");
+				if (routePropertyInfo != null)
+				{
+					var routeType = routePropertyInfo.PropertyType;
+					var routeTemplatePropertyInfo = routeType.GetProperty("RouteTemplate");
+					if (routeTemplatePropertyInfo != null)
+					{
+						var routePropertyGetter = ExpressionBuilder.BuildPropertyGetter(_httpRouteDataInterfaceType, routePropertyInfo);
+						var routeTemplatePropertyGetter = ExpressionBuilder.BuildPropertyGetter(routeType, routeTemplatePropertyInfo);
+						return routeData =>
+						{
+							var route = routePropertyGetter(routeData);
+							return route is null
+								? null
+								: routeTemplatePropertyGetter(route) as string;
+						};
+					}
+				}
+			}
+
+			return null;
+		}
 	}
 }

src/Elastic.Apm/Reflection/ExpressionBuilder.cs

@@ -0,0 +1,38 @@
+// Licensed to Elasticsearch B.V under
+// one or more agreements.
+// Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information
+
+using System;
+using System.Linq.Expressions;
+using System.Reflection;
+
+namespace Elastic.Apm.Reflection
+{
+	internal class ExpressionBuilder
+	{
+		/// <summary>
+		/// Builds a delegate to get a property of type <typeparamref name="TProperty"/> from an object
+		/// of type <typeparamref name="TObject"/>
+		/// </summary>
+		public static Func<TObject, TProperty> BuildPropertyGetter<TObject, TProperty>(string propertyName)
+		{
+			var parameterExpression = Expression.Parameter(typeof(TObject), "value");
+			var memberExpression = Expression.Property(parameterExpression, propertyName);
+			return Expression.Lambda<Func<TObject, TProperty>>(memberExpression, parameterExpression).Compile();
+		}
+
+		/// <summary>
+		/// Builds a delegate to get a property from an object. <paramref name="type"/> is cast to <see cref="Object"/>,
+		/// with the returned property cast to <see cref="Object"/>.
+		/// </summary>
+		public static Func<object, object> BuildPropertyGetter(Type type, PropertyInfo propertyInfo)
+		{
+			var parameterExpression = Expression.Parameter(typeof(object), "value");
+			var parameterCastExpression = Expression.Convert(parameterExpression, type);
+			var memberExpression = Expression.Property(parameterCastExpression, propertyInfo);
+			var returnCastExpression = Expression.Convert(memberExpression, typeof(object));
+			return Expression.Lambda<Func<object, object>>(returnCastExpression, parameterExpression).Compile();
+		}
+	}
+}

test/Elastic.Apm.AspNetFullFramework.Tests/TestsBase.cs

@@ -187,6 +187,9 @@ internal static class SampleAppUrlPaths
 			internal static readonly SampleAppUrlPathData WebApiPage =
 				new SampleAppUrlPathData(WebApiController.Path, 200);
 
+			internal static SampleAppUrlPathData AttributeRoutingWebApiPage(string id) =>
+				new SampleAppUrlPathData(AttributeRoutingWebApiController.RoutePrefix + "/" + id, 200);
+
 			internal static readonly SampleAppUrlPathData WebformsPage =
 				new SampleAppUrlPathData(nameof(Webforms) + ".aspx", 200);
 

test/Elastic.Apm.AspNetFullFramework.Tests/TransactionNameTests.cs

@@ -8,6 +8,7 @@
 using System.Net.Http.Headers;
 using System.Text;
 using System.Threading.Tasks;
+using AspNetFullFrameworkSampleApp.Controllers;
 using FluentAssertions;
 using Xunit;
 using Xunit.Abstractions;
@@ -118,6 +119,20 @@ await WaitAndCustomVerifyReceivedData(receivedData =>
 			});
 		}
 
+		[AspNetFullFrameworkFact]
+		public async Task Name_Should_Be_RouteTemplate_When_WebApi_Attribute_Routing()
+		{
+			var pathData = SampleAppUrlPaths.AttributeRoutingWebApiPage("foo");
+			await SendGetRequestToSampleAppAndVerifyResponse(pathData.Uri, pathData.StatusCode);
+
+			await WaitAndCustomVerifyReceivedData(receivedData =>
+			{
+				receivedData.Transactions.Count.Should().Be(1);
+				var transaction = receivedData.Transactions.Single();
+				transaction.Name.Should().Be($"GET {AttributeRoutingWebApiController.RoutePrefix}/{AttributeRoutingWebApiController.Route}");
+			});
+		}
+
 		[AspNetFullFrameworkFact]
 		public async Task Name_Should_Be_Path_When_Webforms_Page()
 		{