Port AzureWebAppTelemetryInitializer (#332)

Author: xavierdecoster

src/NuGet.Services.Logging/NuGet.Services.Logging.csproj

@@ -50,6 +50,7 @@
   <ItemGroup>
     <Compile Include="ApplicationInsights.cs" />
     <Compile Include="ApplicationInsightsConfiguration.cs" />
+    <Compile Include="TelemetryInitializers\AzureWebAppTelemetryInitializer.cs" />
     <Compile Include="TelemetryInitializers\DeploymentIdTelemetryEnricher.cs" />
     <Compile Include="TelemetryInitializers\DeploymentLabelEnricher.cs" />
     <Compile Include="DurationMetric.cs" />

src/NuGet.Services.Logging/TelemetryInitializers/AzureWebAppTelemetryInitializer.cs

@@ -0,0 +1,32 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using Microsoft.ApplicationInsights.Channel;
+using Microsoft.ApplicationInsights.Extensibility;
+
+namespace NuGet.Services.Logging
+{
+    /// <summary>
+    /// Overrides the initialized telemetry context. This should be added last in
+    /// the Application Insights telemetry list.
+    /// See: https://github.com/microsoft/ApplicationInsights-dotnet-server/blob/e5a0edbe570e0938d3cb7a36a57b25d0db4d3c01/Src/WindowsServer/WindowsServer.Shared/AzureWebAppRoleEnvironmentTelemetryInitializer.cs#L12
+    /// </summary>
+    public class AzureWebAppTelemetryInitializer
+        : ITelemetryInitializer
+    {
+        private const string StagingSlotSuffix = "-staging";
+
+        public void Initialize(ITelemetry telemetry)
+        {
+            // Application Insight's Azure Web App Role Environment telemetry initializer uses
+            // the hostname for the "cloud_roleName" property, which unintentionally creates separate
+            // role names for our production/staging slots.
+            var roleName = telemetry.Context.Cloud.RoleName;
+            if (!string.IsNullOrEmpty(roleName) && roleName.EndsWith(StagingSlotSuffix, StringComparison.OrdinalIgnoreCase))
+            {
+                telemetry.Context.Cloud.RoleName = roleName.Substring(0, roleName.Length - StagingSlotSuffix.Length);
+            }
+        }
+    }
+}

tests/NuGet.Services.Logging.Tests/NuGet.Services.Logging.Tests.csproj

@@ -54,6 +54,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="ApplicationInsightsTests.cs" />
+    <Compile Include="TelemetryInitializers\AzureWebAppTelemetryInitializerFacts.cs" />
     <Compile Include="TelemetryInitializers\DeploymentLabelEnricherTests.cs" />
     <Compile Include="Extensions\DiagnosticsTelemetryModuleExtensionsTests.cs" />
     <Compile Include="ExceptionTelemetryProcessorTests.cs" />

tests/NuGet.Services.Logging.Tests/TelemetryInitializers/AzureWebAppTelemetryInitializerFacts.cs

@@ -0,0 +1,34 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.ApplicationInsights.Channel;
+using Microsoft.ApplicationInsights.DataContracts;
+using Moq;
+using Xunit;
+
+namespace NuGet.Services.Logging.Tests
+{
+    public class AzureWebAppTelemetryInitializerFacts
+    {
+        [Theory]
+        [InlineData(null, null)]
+        [InlineData("hello", "hello")]
+        [InlineData("-staging-test", "-staging-test")]
+        [InlineData("hello-staging", "hello")]
+        [InlineData("hello-sTAGing", "hello")]
+        public void UpdatesRoleName(string input, string expected)
+        {
+            var telemetry = new Mock<ITelemetry>();
+            var context = new TelemetryContext();
+
+            context.Cloud.RoleName = input;
+
+            telemetry.Setup(t => t.Context).Returns(context);
+
+            var target = new AzureWebAppTelemetryInitializer();
+            target.Initialize(telemetry.Object);
+
+            Assert.Equal(expected, context.Cloud.RoleName);
+        }
+    }
+}