Add DisableTelemetry support using OpenTelemetry OTEL_SDK_DISABLED

.publicApi/Microsoft.ApplicationInsights.dll/Stable/PublicAPI.Unshipped.txt

@@ -283,7 +283,6 @@ override Microsoft.ApplicationInsights.Metrics.MetricIdentifier.Equals(object ot
 override Microsoft.ApplicationInsights.Metrics.MetricIdentifier.GetHashCode() -> int
 override Microsoft.ApplicationInsights.Metrics.MetricIdentifier.ToString() -> string
 static Microsoft.ApplicationInsights.Extensibility.TelemetryConfiguration.CreateDefault() -> Microsoft.ApplicationInsights.Extensibility.TelemetryConfiguration
-static Microsoft.ApplicationInsights.Extensibility.TelemetryConfiguration.CreateFromConfiguration(string config) -> Microsoft.ApplicationInsights.Extensibility.TelemetryConfiguration
 static Microsoft.ApplicationInsights.Metrics.MetricIdentifier.DefaultMetricNamespace.get -> string
 static Microsoft.ApplicationInsights.Metrics.MetricIdentifier.DefaultMetricNamespace.set -> void
 static Microsoft.ApplicationInsights.TelemetryClientExtensions.StartOperation<T>(this Microsoft.ApplicationInsights.TelemetryClient telemetryClient, string operationName) -> Microsoft.ApplicationInsights.Extensibility.IOperationHolder<T>

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

@@ -0,0 +1,107 @@
+namespace Microsoft.ApplicationInsights.Tests
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Diagnostics;
+    using System.Linq;
+    using Microsoft.ApplicationInsights.DataContracts;
+    using Microsoft.ApplicationInsights.Extensibility;
+    using Microsoft.Extensions.Logging;
+    using OpenTelemetry;
+    using OpenTelemetry.Logs;
+    using OpenTelemetry.Metrics;
+    using OpenTelemetry.Trace;
+    using Xunit;
+
+    /// <summary>
+    /// Tests for DisableTelemetry property in TelemetryConfiguration.
+    /// Verifies that when DisableTelemetry is set to true, the OTEL_SDK_DISABLED environment variable
+    /// is set and telemetry data does not flow through the OpenTelemetry SDK.
+    /// </summary>
+    [Collection("TelemetryClientTests")]
+    public class TelemetryConfigurationOtelSdkDisabledTests
+    {
+        private const string OtelSdkDisabledEnvVar = "OTEL_SDK_DISABLED";
+
+        [Fact]
+        public void WhenDisableTelemetryIsTrue_TelemetryDataIsNotExported()
+        {
+            // Save original value to restore after test
+            var originalEnvValue = Environment.GetEnvironmentVariable(OtelSdkDisabledEnvVar);
+
+            try
+            {
+                // Arrange
+                var logItems = new List<LogRecord>();
+                var activityItems = new List<Activity>();
+                var configuration = new TelemetryConfiguration();
+                configuration.ConnectionString = "InstrumentationKey=" + Guid.NewGuid().ToString();
+                configuration.DisableTelemetry = true;
+                configuration.ConfigureOpenTelemetryBuilder(b => b
+                    .WithLogging(l => l.AddInMemoryExporter(logItems))
+                    .WithTracing(t => t.AddInMemoryExporter(activityItems)));
+
+                var telemetryClient = new TelemetryClient(configuration);
+
+                // Act
+                telemetryClient.TrackEvent("TestEvent");
+                telemetryClient.TrackTrace("TestTrace");
+                telemetryClient.TrackDependency("HTTP", "example.com", "GET /api", DateTimeOffset.Now, TimeSpan.FromMilliseconds(100), true);
+                telemetryClient.Flush();
+
+                // Assert - No data should be exported when telemetry is disabled
+                Assert.Empty(logItems);
+                Assert.Empty(activityItems);
+                Assert.Equal("true", Environment.GetEnvironmentVariable(OtelSdkDisabledEnvVar));
+
+                // Cleanup
+                configuration.Dispose();
+            }
+            finally
+            {
+                // Restore original environment variable value
+                Environment.SetEnvironmentVariable(OtelSdkDisabledEnvVar, originalEnvValue);
+            }
+        }
+
+        [Fact]
+        public void WhenDisableTelemetryIsFalse_TelemetryDataIsExported()
+        {
+            // Save original value to restore after test
+            var originalEnvValue = Environment.GetEnvironmentVariable(OtelSdkDisabledEnvVar);
+
+            try
+            {
+                // Arrange
+                var logItems = new List<LogRecord>();
+                var configuration = new TelemetryConfiguration();
+                configuration.SamplingRatio = 1.0f;
+                configuration.ConnectionString = "InstrumentationKey=" + Guid.NewGuid().ToString();
+                configuration.DisableTelemetry = false;
+                configuration.ConfigureOpenTelemetryBuilder(b => b
+                    .WithLogging(l => l.AddInMemoryExporter(logItems)));
+
+                var telemetryClient = new TelemetryClient(configuration);
+
+                // Act
+                telemetryClient.TrackEvent("TestEvent");
+                telemetryClient.Flush();
+
+                // Assert - Data should be exported when telemetry is enabled
+                Assert.NotEmpty(logItems);
+                var logRecord = logItems.FirstOrDefault(l =>
+                    l.Attributes != null && l.Attributes.Any(a =>
+                        a.Key == "microsoft.custom_event.name" && a.Value?.ToString() == "TestEvent"));
+                Assert.NotNull(logRecord);
+
+                // Cleanup
+                configuration.Dispose();
+            }
+            finally
+            {
+                // Restore original environment variable value
+                Environment.SetEnvironmentVariable(OtelSdkDisabledEnvVar, originalEnvValue);
+            }
+        }
+    }
+}

BASE/src/Microsoft.ApplicationInsights/Extensibility/TelemetryConfiguration.cs

@@ -226,22 +226,6 @@ public static TelemetryConfiguration CreateDefault()
             return DefaultInstance.Value;
         }
 
-        /// <summary>
-        /// Creates a new <see cref="TelemetryConfiguration"/> instance loaded from the specified configuration.
-        /// </summary>
-        /// <param name="config">An xml serialized configuration.</param>
-        /// <exception cref="ArgumentNullException">Throws if the config value is null or empty.</exception>
-        public static TelemetryConfiguration CreateFromConfiguration(string config)
-        {
-            if (string.IsNullOrWhiteSpace(config))
-            {
-                throw new ArgumentNullException(nameof(config));
-            }
-
-            var configuration = new TelemetryConfiguration();
-            return configuration;
-        }
-
         /// <summary>
         /// Allows extending the OpenTelemetry builder configuration.
         /// </summary>
@@ -365,6 +349,8 @@ internal OpenTelemetrySdk Build()
                     return this.openTelemetrySdk;
                 }
 
+                Environment.SetEnvironmentVariable("OTEL_SDK_DISABLED", this.disableTelemetry ? "true" : "false");
+
                 this.openTelemetrySdk = OpenTelemetrySdk.Create(builder =>
                 {
                     this.builderConfiguration(builder);

BASE/src/Microsoft.ApplicationInsights/TelemetryClientExtensions.cs

@@ -53,7 +53,7 @@
      string parentOperationId = null)
      where T : OperationTelemetry, new()
         {
             if (telemetryClient == null)
             {
                 throw new ArgumentNullException(nameof(telemetryClient));
             }
@@ -135,12 +135,12 @@
             T operationTelemetry)
             where T : OperationTelemetry
         {
             if (telemetryClient == null)
             {
                 throw new ArgumentNullException(nameof(telemetryClient));
             }
 
             if (operationTelemetry == null)
             {
                 throw new ArgumentNullException(nameof(operationTelemetry));
             }
@@ -217,14 +217,14 @@
             Activity activity)
             where T : OperationTelemetry, new()
         {
             if (telemetryClient == null)
             {
                 throw new ArgumentNullException(nameof(telemetryClient));
             }
 
             if (activity == null)
             {
-                throw new ArgumentNullException(nameof(activity));
+                return null;
             }
 
             // if already started activity, we just link it — not create a new one
@@ -269,7 +269,7 @@
             IOperationHolder<T> operation)
             where T : OperationTelemetry
         {
             if (telemetryClient == null)
             {
                 throw new ArgumentNullException(nameof(telemetryClient));
             }

CHANGELOG.md

@@ -3,7 +3,6 @@
 ## Unreleased
 
 - [The JavaScript in `Microsoft.ApplicationInsights.AspNetCore` has been updated to version 10.](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3078)
-
 - [Centralized package version management](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3080)
 - [Update OpenTelemetry dependencies](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3080)
   - OpenTelemetry 1.15.0
@@ -12,7 +11,8 @@
   - OpenTelemetry.Instrumentation.Http 1.15.0
   - OpenTelemetry.Instrumentation.SqlClient 1.15.0-rc.1
   - OpenTelemetry.Resources.Azure 1.15.0-beta.1
-
+- [Added support to disable telemetry via TelemetryConfiguration.DisableTelemetry](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3084)
+
 ## Version 3.0.0-beta2
 ### Added
 - [Automatic configuration binding from "ApplicationInsights" section in appsettings.json for both AspNetCore and WorkerService packages with configuration precedence: environment variables > explicit configuration > appsettings.json](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3064)

NETCORE/src/Microsoft.ApplicationInsights.AspNetCore/Extensions/ApplicationInsightsExtensions.cs

@@ -9,6 +9,7 @@
     using Microsoft.ApplicationInsights.AspNetCore;
     using Microsoft.ApplicationInsights.AspNetCore.Extensibility.Implementation.Tracing;
     using Microsoft.ApplicationInsights.AspNetCore.Extensions;
+    using Microsoft.ApplicationInsights.Extensibility;
     using Microsoft.ApplicationInsights.Extensibility.Implementation.Tracing;
     using Microsoft.ApplicationInsights.Internals;
     using Microsoft.Extensions.Configuration;
@@ -188,9 +189,15 @@ internal static IOpenTelemetryBuilder UseApplicationInsightsTelemetry(this IOpen
 
             // Configure Azure Monitor Exporter with connection string and sampling from ApplicationInsightsServiceOptions
             builder.Services.AddOptions<AzureMonitorExporterOptions>()
-                .Configure<IOptions<ApplicationInsightsServiceOptions>>((exporterOptions, aiOptions) =>
+                .Configure<IOptions<ApplicationInsightsServiceOptions>, TelemetryConfiguration, IConfiguration>((exporterOptions, aiOptions, telemetryConfig, config) =>
                 {
                     var serviceOptions = aiOptions.Value;
+
+                    // Set OTEL_SDK_DISABLED in configuration if DisableTelemetry is true
+                    if (telemetryConfig.DisableTelemetry)
+                    {
+                        config["OTEL_SDK_DISABLED"] = "true";
+                    }
 
                     // Copy connection string to Azure Monitor Exporter
                     if (!string.IsNullOrEmpty(serviceOptions.ConnectionString))

NETCORE/src/Microsoft.ApplicationInsights.WorkerService/ApplicationInsightsExtensions.cs

@@ -6,6 +6,7 @@
     using System.Reflection;
     using Azure.Monitor.OpenTelemetry.Exporter;
     using Microsoft.ApplicationInsights;
+    using Microsoft.ApplicationInsights.Extensibility;
     using Microsoft.ApplicationInsights.Extensibility.Implementation.Tracing;
     using Microsoft.ApplicationInsights.Internals;
     using Microsoft.ApplicationInsights.WorkerService;
@@ -183,10 +184,16 @@ internal static IOpenTelemetryBuilder UseApplicationInsightsTelemetry(this IOpen
 
             // Configure Azure Monitor Exporter with connection string and sampling from ApplicationInsightsServiceOptions
             builder.Services.AddOptions<AzureMonitorExporterOptions>()
-                .Configure<IOptions<ApplicationInsightsServiceOptions>>((exporterOptions, aiOptions) =>
+                .Configure<IOptions<ApplicationInsightsServiceOptions>, TelemetryConfiguration, IConfiguration>((exporterOptions, aiOptions, telemetryConfig, config) =>
                 {
                     var serviceOptions = aiOptions.Value;
 
+                    // Set OTEL_SDK_DISABLED in configuration if DisableTelemetry is true
+                    if (telemetryConfig.DisableTelemetry)
+                    {
+                        config["OTEL_SDK_DISABLED"] = "true";
+                    }
+
                     // Copy connection string to Azure Monitor Exporter
                     if (!string.IsNullOrEmpty(serviceOptions.ConnectionString))
                     {

NETCORE/src/Shared/Extensions/ApplicationInsightsExtensions.cs

@@ -92,7 +92,8 @@ private static void AddTelemetryConfigAndClient(IServiceCollection services)
         {
             services.AddOptions();
 
-            // Register TelemetryConfiguration as singleton with factory that creates it for DI scenarios
+            // Register TelemetryConfiguration singleton with factory that creates it for DI scenarios
+            // We use a factory to ensure skipDefaultBuilderConfiguration: true is passed
             services.AddSingleton<TelemetryConfiguration>(provider =>
             {
                 var options = provider.GetRequiredService<IOptions<ApplicationInsightsServiceOptions>>().Value;
@@ -105,6 +106,19 @@ private static void AddTelemetryConfigAndClient(IServiceCollection services)
                 {
                     configuration.ConnectionString = options.ConnectionString;
                 }
+
+                // Apply any Configure<TelemetryConfiguration> callbacks
+                var configureOptions = provider.GetServices<IConfigureOptions<TelemetryConfiguration>>();
+                foreach (var configure in configureOptions)
+                {
+                    configure.Configure(configuration);
+                }
+
+                var postConfigureOptions = provider.GetServices<IPostConfigureOptions<TelemetryConfiguration>>();
+                foreach (var postConfigure in postConfigureOptions)
+                {
+                    postConfigure.PostConfigure(Options.DefaultName, configuration);
+                }
 
                 return configuration;
             });

docs/concepts.md

@@ -58,3 +58,36 @@ Please review our full guide on [Telemetry correlation in Application Insights](
 Sampling is the recommended way to reduce telemetry traffic, data costs, and storage costs, while preserving a statistically correct analysis of application data.
 
 Please review our full guide on [Sampling in Application Insights](https://docs.microsoft.com/azure/azure-monitor/app/sampling).
+
+
+## Disabling Telemetry
+
+You can disable all telemetry collection using the `DisableTelemetry` property:
+
+```C#
+var configuration = TelemetryConfiguration.CreateDefault();
+configuration.ConnectionString = "InstrumentationKey=00000000-0000-0000-0000-000000000000";
+configuration.DisableTelemetry = true;
+var tc = new TelemetryClient(configuration);
+```
+
+When `DisableTelemetry` is set to `true`, the SDK internally sets the `OTEL_SDK_DISABLED` environment variable to `true` before building the OpenTelemetry SDK. This causes the OpenTelemetry SDK (version 1.15.0+) to return no-op implementations for all telemetry signals, preventing any telemetry data from being collected or exported.
+
+**Note:** The `DisableTelemetry` property must be set before the first `TelemetryClient` is created, as the OpenTelemetry SDK is built at that time.
+
+### Disabling Telemetry in DI Scenarios (ASP.NET Core / Worker Service)
+
+For dependency injection scenarios, you must configure `DisableTelemetry` **before** calling `AddApplicationInsightsTelemetry()`:
+
+```C#
+public void ConfigureServices(IServiceCollection services)
+{
+    // Configure DisableTelemetry BEFORE AddApplicationInsightsTelemetry
+    services.Configure<TelemetryConfiguration>(tc => tc.DisableTelemetry = true);
+
+    // Add and initialize the Application Insights SDK
+    services.AddApplicationInsightsTelemetry();
+}
+```
+
+This ensures the `OTEL_SDK_DISABLED` environment variable is set before the OpenTelemetry SDK is initialized.

examples/AspNetCoreWebApp/Startup.cs

@@ -1,5 +1,6 @@
 namespace AspNetCoreWebApp
 {
+    using Microsoft.ApplicationInsights.Extensibility;
     using Microsoft.AspNetCore.Builder;
     using Microsoft.AspNetCore.Hosting;
     using Microsoft.Extensions.Configuration;
@@ -26,6 +27,8 @@ public void ConfigureServices(IServiceCollection services)
 
             });*/
 
+            // services.Configure<TelemetryConfiguration>(tc => tc.DisableTelemetry = true);
+
             // Add and initialize the Application Insights SDK.
             services.AddApplicationInsightsTelemetry();
             /*services.AddApplicationInsightsTelemetry(new ApplicationInsightsServiceOptions