Fix: Cloud RoleName/Instance update applies to all telemetry

BASE/Test/Microsoft.ApplicationInsights.Test/Microsoft.ApplicationInsights.Tests/TelemetryClientTest.cs

@@ -2151,6 +2151,24 @@ public void TrackRequest_BothUserIdAndAuthenticatedUserId_MapsToBothAttributes()
 
         #endregion
 
+        [Fact]
+        public void CloudContextRoleNameSetsEnvironmentVariable()
+        {
+            try
+            {
+                this.telemetryClient.Context.Cloud.RoleName = "TestRoleName";
+                Assert.Equal("TestRoleName", Environment.GetEnvironmentVariable("APPLICATIONINSIGHTS_CLOUD_ROLE_NAME"));
+
+                this.telemetryClient.Context.Cloud.RoleInstance = "TestRoleInstance";
+                Assert.Equal("TestRoleInstance", Environment.GetEnvironmentVariable("APPLICATIONINSIGHTS_CLOUD_ROLE_INSTANCE"));
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable("APPLICATIONINSIGHTS_CLOUD_ROLE_NAME", null);
+                Environment.SetEnvironmentVariable("APPLICATIONINSIGHTS_CLOUD_ROLE_INSTANCE", null);
+            }
+        }
+
         private double ComputeSomethingHeavy()
         {
             var random = new Random();

BASE/src/Microsoft.ApplicationInsights/Extensibility/Implementation/CloudContext.cs

@@ -1,10 +1,22 @@
 namespace Microsoft.ApplicationInsights.Extensibility.Implementation
 {
+    using System;
+
     /// <summary>
     /// Encapsulates information about a cloud where an application is running.
     /// </summary>
     internal sealed class CloudContext
     {
+        /// <summary>
+        /// Environment variable key used to communicate cloud role name override to the exporter.
+        /// </summary>
+        internal const string CloudRoleNameEnvironmentVariable = "APPLICATIONINSIGHTS_CLOUD_ROLE_NAME";
+
+        /// <summary>
+        /// Environment variable key used to communicate cloud role instance override to the exporter.
+        /// </summary>
+        internal const string CloudRoleInstanceEnvironmentVariable = "APPLICATIONINSIGHTS_CLOUD_ROLE_INSTANCE";
+
         private string roleName;
         private string roleInstance;
 
@@ -17,17 +29,33 @@ internal CloudContext()
         /// </summary>
         public string RoleName
         {
-            get { return string.IsNullOrEmpty(this.roleName) ? null : this.roleName; }
-            set { this.roleName = value; }
+            get
+            {
+                return string.IsNullOrEmpty(this.roleName) ? null : this.roleName;
+            }
+
+            set
+            {
+                this.roleName = value;
+                Environment.SetEnvironmentVariable(CloudRoleNameEnvironmentVariable, value);
+            }
         }
 
         /// <summary>
         /// Gets or sets the role instance.
         /// </summary>
         public string RoleInstance
         {
-            get { return string.IsNullOrEmpty(this.roleInstance) ? null : this.roleInstance; }
-            set { this.roleInstance = value; }
+            get
+            {
+                return string.IsNullOrEmpty(this.roleInstance) ? null : this.roleInstance;
+            }
+
+            set
+            {
+                this.roleInstance = value;
+                Environment.SetEnvironmentVariable(CloudRoleInstanceEnvironmentVariable, value);
+            }
         }
     }
 }

CHANGELOG.md

@@ -1,7 +1,8 @@
 # Changelog
 
 ## Unreleased
-- [Fix bug where Debug/Trace level logs from TrackTrace API were not emitted to Application Insights](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3121/changes)
+- [Fix `TelemetryClient.Context.Cloud.RoleName` set after construction now applies to all telemetry.](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3129)
+- [Fix bug where Debug/Trace level logs from TrackTrace API were not emitted to Application Insights](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3121)
 - [Fix Track API calls to not mutate the passed in dictionary if it is readonly](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3119)
 - [Fix `NullReferenceException` in `TelemetryClient.Flush()` and `FlushAsync()` when called from DI scenarios](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3125)
 - [Fix `ApplicationVersion` ignored: `ApplicationInsightsServiceOptions.ApplicationVersion` is now applied as `service.version` on the OpenTelemetry Resource for both AspNetCore and WorkerService packages](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3124)