[AzureMonitorExporter] Prevent multiple Azure Monitor Exporter registrations on the same IServiceCollection (Azure#48926)

* Prevent multiple Azure Monitor Exporter registrations on the same IServiceCollection

* Add EnsureSingleUseAzureMonitorExporterRegistration at metrics

Author: rajkumar-rangaraj

sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/AzureMonitorExporterExtensions.cs

@@ -82,6 +82,8 @@ public static TracerProviderBuilder AddAzureMonitorTraceExporter(
                     exporterOptions.Credential ??= credential;
                 }
 
+                sp.EnsureNoUseAzureMonitorExporterRegistrations();
+
                 builder.AddProcessor(new CompositeProcessor<Activity>(new BaseProcessor<Activity>[]
                 {
                     new StandardMetricsExtractionProcessor(new AzureMonitorMetricExporter(exporterOptions)),
@@ -143,6 +145,8 @@ public static MeterProviderBuilder AddAzureMonitorMetricExporter(
                     exporterOptions.Credential ??= credential;
                 }
 
+                sp.EnsureNoUseAzureMonitorExporterRegistrations();
+
                 return new PeriodicExportingMetricReader(new AzureMonitorMetricExporter(exporterOptions))
                 { TemporalityPreference = MetricReaderTemporalityPreference.Delta };
             });
@@ -239,6 +243,8 @@ public static LoggerProviderBuilder AddAzureMonitorLogExporter(
                     exporterOptions.Credential ??= credential;
                 }
 
+                sp.EnsureNoUseAzureMonitorExporterRegistrations();
+
                 // TODO: Do we need provide an option to alter BatchExportLogRecordProcessorOptions?
                 return new BatchLogRecordExportProcessor(new AzureMonitorLogExporter(exporterOptions));
             });

sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/ExporterRegistrationHostedService.cs

@@ -53,6 +53,9 @@ private static void Initialize(IServiceProvider serviceProvider)
             var tracerProvider = serviceProvider!.GetService<TracerProvider>();
             if (tracerProvider != null)
             {
+                // Ensure that the AzureMonitorTraceExporter is registered only once
+                serviceProvider!.EnsureSingleUseAzureMonitorExporterRegistration();
+
                 // Add a processor manually to the TracerProvider created by the SDK
                 var exporterOptions = serviceProvider!.GetRequiredService<IOptionsMonitor<AzureMonitorExporterOptions>>().Get(Options.DefaultName);
 
@@ -73,6 +76,9 @@ private static void Initialize(IServiceProvider serviceProvider)
             var loggerProvider = serviceProvider!.GetService<LoggerProvider>();
             if (loggerProvider != null)
             {
+                // Ensure that the AzureMonitorLogExporter is registered only once
+                serviceProvider!.EnsureSingleUseAzureMonitorExporterRegistration();
+
                 // Add a processor manually to the LoggerProvider created by the SDK
                 var exporterOptions = serviceProvider!.GetRequiredService<IOptionsMonitor<AzureMonitorExporterOptions>>().Get(Options.DefaultName);
                 var exporter = new AzureMonitorLogExporter(exporterOptions);

sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/OpenTelemetryBuilderExtensions.cs

@@ -12,6 +12,7 @@
 using OpenTelemetry;
 using OpenTelemetry.Logs;
 using System;
+using OpenTelemetry.Metrics;
 
 namespace Azure.Monitor.OpenTelemetry.Exporter
 {
@@ -64,21 +65,33 @@ public static IOpenTelemetryBuilder UseAzureMonitorExporter(this IOpenTelemetryB
                 builder.Services.Configure(configureAzureMonitor);
             }
 
+            builder.Services.AddSingleton(UseAzureMonitorExporterRegistration.Instance);
+
             // Note: We automatically turn on signals for "UseAzureMonitorExporter"
             builder
                 .WithLogging()
-                .WithMetrics(metrics => metrics.AddAzureMonitorMetricExporter())
+                .WithMetrics()
                 .WithTracing();
 
             builder.Services.Configure<OpenTelemetryLoggerOptions>((loggingOptions) =>
             {
                 loggingOptions.IncludeFormattedMessage = true;
             });
 
+            builder.Services.ConfigureOpenTelemetryMeterProvider((serviceProvider, meterProviderBuilder) =>
+            {
+                // Ensure that the AzureMonitorMetricExporter is registered only once
+                serviceProvider!.EnsureSingleUseAzureMonitorExporterRegistration();
+
+                var exporterOptions = serviceProvider!.GetRequiredService<IOptionsMonitor<AzureMonitorExporterOptions>>().Get(Options.DefaultName);
+                meterProviderBuilder.AddReader(new PeriodicExportingMetricReader(new AzureMonitorMetricExporter(exporterOptions))
+                    { TemporalityPreference = MetricReaderTemporalityPreference.Delta });
+            });
+
             // Register Manager as a singleton
-            builder.Services.TryAddSingleton<LiveMetricsClientManager>(sp =>
+            builder.Services.TryAddSingleton<LiveMetricsClientManager>(serviceProvider =>
             {
-                AzureMonitorExporterOptions exporterOptions = sp.GetRequiredService<IOptionsMonitor<AzureMonitorExporterOptions>>().Get(Options.DefaultName);
+                AzureMonitorExporterOptions exporterOptions = serviceProvider.GetRequiredService<IOptionsMonitor<AzureMonitorExporterOptions>>().Get(Options.DefaultName);
                 var azureMonitorLiveMetricsOptions = new AzureMonitorLiveMetricsOptions();
                 exporterOptions.SetValueToLiveMetricsOptions(azureMonitorLiveMetricsOptions);
 
@@ -95,9 +108,9 @@ public static IOpenTelemetryBuilder UseAzureMonitorExporter(this IOpenTelemetryB
                     }
                 });
 
-            builder.Services.AddHostedService(sp =>
+            builder.Services.AddHostedService(serviceProvider =>
             {
-                return new ExporterRegistrationHostedService(sp);
+                return new ExporterRegistrationHostedService(serviceProvider);
             });
 
             return builder;

sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/OpenTelemetryBuilderServiceProviderExtensions.cs

@@ -0,0 +1,30 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using System.Linq;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Azure.Monitor.OpenTelemetry.Exporter
+{
+    internal static class OpenTelemetryBuilderServiceProviderExtensions
+    {
+        public static void EnsureSingleUseAzureMonitorExporterRegistration(this IServiceProvider serviceProvider)
+        {
+            var registrations = serviceProvider.GetServices<UseAzureMonitorExporterRegistration>();
+            if (registrations.Count() > 1)
+            {
+                throw new NotSupportedException("Multiple calls to UseAzureMonitorExporter on the same IServiceCollection are not supported.");
+            }
+        }
+
+        public static void EnsureNoUseAzureMonitorExporterRegistrations(this IServiceProvider serviceProvider)
+        {
+            var registrations = serviceProvider.GetServices<UseAzureMonitorExporterRegistration>();
+            if (registrations.Any())
+            {
+                throw new NotSupportedException("Signal-specific AddAzureMonitorExporter / UseAzureMonitor methods and the cross-cutting UseAzureMonitorExporter method being invoked on the same IServiceCollection is not supported.");
+            }
+        }
+    }
+}

sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/UseAzureMonitorExporterRegistration.cs

@@ -0,0 +1,22 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+namespace Azure.Monitor.OpenTelemetry.Exporter;
+
+// Note: This class is added to the IServiceCollection when UseAzureMonitorExporter is
+// called. Its purpose is to detect registrations so that subsequent calls and
+// calls to signal-specific UseAzureMonitorExporter can throw.
+internal sealed class UseAzureMonitorExporterRegistration
+{
+    public static readonly UseAzureMonitorExporterRegistration Instance = new();
+
+    private UseAzureMonitorExporterRegistration()
+    {
+        // Note: Some dependency injection containers (ex: Unity, Grace) will
+        // automatically create services if they have a public constructor even
+        // if the service was never registered into the IServiceCollection. The
+        // behavior of UseAzureMonitorExporterRegistration requires that it should only
+        // exist if registered. This private constructor is intended to prevent
+        // automatic instantiation.
+    }
+}