Restore OTEL_SDK_DISABLED in AzureMonitorExporterOptions callbacks

CHANGELOG.md

@@ -1,7 +1,7 @@
 # Changelog
 
 ## Unreleased
-- [Fix `DisableTelemetry` not disabling metrics export: `OTEL_SDK_DISABLED` was set in IConfiguration too late (during options callback) after the OTel MeterProvider had already been constructed. Moved the check to a hosted service that runs before OpenTelemetry's TelemetryHostedService.](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3156)
+- [Fix `OTEL_SDK_DISABLED` not being honored when `TelemetryConfiguration.DisableTelemetry` is set in DI scenarios.](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3156), [#3157](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3157)
 - [Fix `TrackAvailability` ignoring user-specified `Timestamp` on `AvailabilityTelemetry`. The timestamp is now emitted as `microsoft.availability.testTimestamp` so downstream exporters can use the correct event time.](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3153)
 - [Added `netstandard2.0` target framework to `Microsoft.ApplicationInsights` package to support customers with shared libraries targeting netstandard2.0.](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3142)
 - [Fix `TelemetryClient.Context.Cloud.RoleName` set after construction now applies to all telemetry.](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3129)

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

@@ -99,7 +99,7 @@
                         .WithApplicationInsights()
                         .UseApplicationInsightsTelemetry();
 
                     AddTelemetryConfigAndClient(services, VersionUtils.ExtensionLabelShimAspNetCore + VersionUtils.GetVersion(typeof(ApplicationInsightsExtensions)));
                     services.AddSingleton<IJavaScriptSnippet, JavaScriptSnippet>();
                     services.AddSingleton<JavaScriptSnippet>();
                 }
@@ -205,6 +205,12 @@
                 {
                     var serviceOptions = aiOptions.Value;
 
+                    // Set OTEL_SDK_DISABLED in configuration if DisableTelemetry is true
+                    if (telemetryConfig.DisableTelemetry)
+                    {
+                        config["OTEL_SDK_DISABLED"] = "true";
+                    }
+
                     if (!string.IsNullOrEmpty(telemetryConfig.StorageDirectory))
                     {
                         exporterOptions.StorageDirectory = telemetryConfig.StorageDirectory;

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

@@ -98,7 +98,7 @@
                             .WithApplicationInsights()
                             .UseApplicationInsightsTelemetry();
 
                     AddTelemetryConfigAndClient(services, VersionUtils.ExtensionLabelShimWorkerService + VersionUtils.GetVersion(typeof(ApplicationInsightsExtensions)));
                 }
 
                 return services;
@@ -200,6 +200,12 @@
                 {
                     var serviceOptions = aiOptions.Value;
 
+                    // Set OTEL_SDK_DISABLED in configuration if DisableTelemetry is true
+                    if (telemetryConfig.DisableTelemetry)
+                    {
+                        config["OTEL_SDK_DISABLED"] = "true";
+                    }
+
                     if (!string.IsNullOrEmpty(telemetryConfig.StorageDirectory))
                     {
                         exporterOptions.StorageDirectory = telemetryConfig.StorageDirectory;

NETCORE/src/Shared/Extensions/ApplicationInsightsExtensions.cs

@@ -20,6 +20,7 @@
 
     using Microsoft.Extensions.Configuration;
     using Microsoft.Extensions.Logging;
+    using Microsoft.Extensions.Logging.Abstractions;
     using Microsoft.Extensions.Options;
 
     /// <summary>
@@ -92,6 +93,17 @@ private static void AddTelemetryConfigAndClient(IServiceCollection services, str
         {
             services.AddOptions();
 
+            // Register a no-op ILoggerProvider at position 0 that depends on TelemetryConfiguration.
+            // ILoggerFactory resolves all ILoggerProvider instances in registration order during host
+            // construction. By inserting this first, TelemetryConfiguration is resolved (which sets
+            // OTEL_SDK_DISABLED in IConfiguration) before OpenTelemetry's LoggerProvider factory runs.
+            // Without this, LoggerProvider checks IConfiguration before OTEL_SDK_DISABLED is set.
+            services.Insert(0, ServiceDescriptor.Singleton<ILoggerProvider>(sp =>
+            {
+                _ = sp.GetRequiredService<TelemetryConfiguration>();
+                return NullLoggerProvider.Instance;
+            }));
+
             // 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 =>