[Tracing] Improve dependency injection support in tracing build-up using SDK

examples/MicroserviceExample/WorkerService/Program.cs

@@ -37,7 +37,7 @@ public static void Main(string[] args)
 
                     services.AddSingleton<MessageReceiver>();
 
-                    services.AddOpenTelemetryTracing((builder) =>
+                    services.AddOpenTelemetryTracing(builder =>
                     {
                         builder
                             .AddSource(nameof(MessageReceiver))

src/OpenTelemetry.Extensions.Hosting/.publicApi/netstandard2.0/PublicAPI.Unshipped.txt

@@ -1,6 +1,5 @@
 Microsoft.Extensions.DependencyInjection.OpenTelemetryServicesExtensions
 OpenTelemetry.Metrics.MeterProviderBuilderExtensions
-OpenTelemetry.Trace.TracerProviderBuilderExtensions
 static Microsoft.Extensions.DependencyInjection.OpenTelemetryServicesExtensions.AddOpenTelemetryMetrics(this Microsoft.Extensions.DependencyInjection.IServiceCollection services) -> Microsoft.Extensions.DependencyInjection.IServiceCollection
 static Microsoft.Extensions.DependencyInjection.OpenTelemetryServicesExtensions.AddOpenTelemetryMetrics(this Microsoft.Extensions.DependencyInjection.IServiceCollection services, System.Action<OpenTelemetry.Metrics.MeterProviderBuilder> configure) -> Microsoft.Extensions.DependencyInjection.IServiceCollection
 static Microsoft.Extensions.DependencyInjection.OpenTelemetryServicesExtensions.AddOpenTelemetryTracing(this Microsoft.Extensions.DependencyInjection.IServiceCollection services) -> Microsoft.Extensions.DependencyInjection.IServiceCollection
@@ -10,9 +9,3 @@ static OpenTelemetry.Metrics.MeterProviderBuilderExtensions.AddReader<T>(this Op
 static OpenTelemetry.Metrics.MeterProviderBuilderExtensions.Build(this OpenTelemetry.Metrics.MeterProviderBuilder meterProviderBuilder, System.IServiceProvider serviceProvider) -> OpenTelemetry.Metrics.MeterProvider
 static OpenTelemetry.Metrics.MeterProviderBuilderExtensions.Configure(this OpenTelemetry.Metrics.MeterProviderBuilder meterProviderBuilder, System.Action<System.IServiceProvider, OpenTelemetry.Metrics.MeterProviderBuilder> configure) -> OpenTelemetry.Metrics.MeterProviderBuilder
 static OpenTelemetry.Metrics.MeterProviderBuilderExtensions.GetServices(this OpenTelemetry.Metrics.MeterProviderBuilder meterProviderBuilder) -> Microsoft.Extensions.DependencyInjection.IServiceCollection
-static OpenTelemetry.Trace.TracerProviderBuilderExtensions.AddInstrumentation<T>(this OpenTelemetry.Trace.TracerProviderBuilder tracerProviderBuilder) -> OpenTelemetry.Trace.TracerProviderBuilder
-static OpenTelemetry.Trace.TracerProviderBuilderExtensions.AddProcessor<T>(this OpenTelemetry.Trace.TracerProviderBuilder tracerProviderBuilder) -> OpenTelemetry.Trace.TracerProviderBuilder
-static OpenTelemetry.Trace.TracerProviderBuilderExtensions.Build(this OpenTelemetry.Trace.TracerProviderBuilder tracerProviderBuilder, System.IServiceProvider serviceProvider) -> OpenTelemetry.Trace.TracerProvider
-static OpenTelemetry.Trace.TracerProviderBuilderExtensions.Configure(this OpenTelemetry.Trace.TracerProviderBuilder tracerProviderBuilder, System.Action<System.IServiceProvider, OpenTelemetry.Trace.TracerProviderBuilder> configure) -> OpenTelemetry.Trace.TracerProviderBuilder
-static OpenTelemetry.Trace.TracerProviderBuilderExtensions.GetServices(this OpenTelemetry.Trace.TracerProviderBuilder tracerProviderBuilder) -> Microsoft.Extensions.DependencyInjection.IServiceCollection
-static OpenTelemetry.Trace.TracerProviderBuilderExtensions.SetSampler<T>(this OpenTelemetry.Trace.TracerProviderBuilder tracerProviderBuilder) -> OpenTelemetry.Trace.TracerProviderBuilder

src/OpenTelemetry.Extensions.Hosting/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+* Dependency injection support when configuring
+  `TracerProvider` has been moved into the SDK.
+  ([#3533](https://github.com/open-telemetry/opentelemetry-dotnet/pull/3533))
+
 ## 1.0.0-rc9.6
 
 Released 2022-Aug-18

src/OpenTelemetry.Extensions.Hosting/Implementation/TelemetryHostedService.cs

@@ -15,49 +15,56 @@
 // </copyright>
 
 using System;
+using System.Diagnostics;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using OpenTelemetry.Metrics;
 using OpenTelemetry.Trace;
 
-namespace OpenTelemetry.Extensions.Hosting.Implementation
+namespace OpenTelemetry.Extensions.Hosting.Implementation;
+
+internal sealed class TelemetryHostedService : IHostedService
 {
-    internal class TelemetryHostedService : IHostedService
+    private readonly IServiceProvider serviceProvider;
+
+    public TelemetryHostedService(IServiceProvider serviceProvider)
     {
-        private readonly IServiceProvider serviceProvider;
+        this.serviceProvider = serviceProvider;
+    }
 
-        public TelemetryHostedService(IServiceProvider serviceProvider)
+    public Task StartAsync(CancellationToken cancellationToken)
+    {
+        try
         {
-            this.serviceProvider = serviceProvider;
+            // The sole purpose of this HostedService is to ensure all
+            // instrumentations, exporters, etc., are created and started.
+            Initialize(this.serviceProvider);
         }
-
-        public Task StartAsync(CancellationToken cancellationToken)
+        catch (Exception ex)
         {
-            try
-            {
-                // The sole purpose of this HostedService is to ensure all
-                // instrumentations, exporters, etc., are created and started.
-                var meterProvider = this.serviceProvider.GetService<MeterProvider>();
-                var tracerProvider = this.serviceProvider.GetService<TracerProvider>();
-
-                if (meterProvider == null && tracerProvider == null)
-                {
-                    throw new InvalidOperationException("Could not resolve either MeterProvider or TracerProvider through application ServiceProvider, OpenTelemetry SDK has not been initialized.");
-                }
-            }
-            catch (Exception ex)
-            {
-                HostingExtensionsEventSource.Log.FailedOpenTelemetrySDK(ex);
-            }
-
-            return Task.CompletedTask;
+            HostingExtensionsEventSource.Log.FailedOpenTelemetrySDK(ex);
         }
 
-        public Task StopAsync(CancellationToken cancellationToken)
+        return Task.CompletedTask;
+    }
+
+    public Task StopAsync(CancellationToken cancellationToken)
+    {
+        return Task.CompletedTask;
+    }
+
+    internal static void Initialize(IServiceProvider serviceProvider)
+    {
+        Debug.Assert(serviceProvider != null, "serviceProvider was null");
+
+        var meterProvider = serviceProvider.GetService<MeterProvider>();
+        var tracerProvider = serviceProvider.GetService<TracerProvider>();
+
+        if (meterProvider == null && tracerProvider == null)
         {
-            return Task.CompletedTask;
+            throw new InvalidOperationException("Could not resolve either MeterProvider or TracerProvider through application ServiceProvider, OpenTelemetry SDK has not been initialized.");
         }
     }
 }

src/OpenTelemetry.Extensions.Hosting/OpenTelemetry.Extensions.Hosting.csproj

@@ -1,8 +1,8 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <!-- OmniSharp/VS Code requires TargetFrameworks to be in descending order for IntelliSense and analysis. -->
     <TargetFrameworks>netstandard2.0</TargetFrameworks>
-    <Description>Startup extensions to register OpenTelemetry into the applications using Microsoft.Extensions.DependencyInjection and Microsoft.Extensions.Hosting</Description>
+    <Description>Contains extensions to register and start OpenTelemetry in applications using Microsoft.Extensions.Hosting</Description>
     <RootNamespace>OpenTelemetry</RootNamespace>
   </PropertyGroup>
 

src/OpenTelemetry.Extensions.Hosting/OpenTelemetryServicesExtensions.cs

@@ -32,28 +32,38 @@ namespace Microsoft.Extensions.DependencyInjection
     public static class OpenTelemetryServicesExtensions
     {
         /// <summary>
-        /// Adds OpenTelemetry TracerProvider to the specified <see cref="IServiceCollection" />.
+        /// Configure OpenTelemetry and register a <see cref="IHostedService"/>
+        /// to automatically start tracing services in the supplied <see
+        /// cref="IServiceCollection" />.
         /// </summary>
-        /// <param name="services">The <see cref="IServiceCollection" /> to add services to.</param>
-        /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns>
+        /// <remarks>
+        /// Note: This is safe to be called multiple times and by library authors.
+        /// Only a single <see cref="TracerProvider"/> will be created for a given
+        /// <see cref="IServiceCollection"/>.
+        /// </remarks>
+        /// <param name="services"><see cref="IServiceCollection"/>.</param>
+        /// <returns>Supplied <see cref="IServiceCollection"/> for chaining calls.</returns>
         public static IServiceCollection AddOpenTelemetryTracing(this IServiceCollection services)
-        {
-            return services.AddOpenTelemetryTracing(builder => { });
-        }
+            => AddOpenTelemetryTracing(services, (b) => { });
 
         /// <summary>
-        /// Adds OpenTelemetry TracerProvider to the specified <see cref="IServiceCollection" />.
+        /// Configure OpenTelemetry and register a <see cref="IHostedService"/>
+        /// to automatically start tracing services in the supplied <see
+        /// cref="IServiceCollection" />.
         /// </summary>
-        /// <param name="services">The <see cref="IServiceCollection" /> to add services to.</param>
+        /// <remarks><inheritdoc cref="AddOpenTelemetryTracing(IServiceCollection)" path="/remarks"/></remarks>
+        /// <param name="services"><see cref="IServiceCollection"/>.</param>
         /// <param name="configure">Callback action to configure the <see cref="TracerProviderBuilder"/>.</param>
-        /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns>
+        /// <returns>Supplied <see cref="IServiceCollection"/> for chaining calls.</returns>
         public static IServiceCollection AddOpenTelemetryTracing(this IServiceCollection services, Action<TracerProviderBuilder> configure)
         {
-            Guard.ThrowIfNull(configure);
+            Guard.ThrowIfNull(services);
 
-            var builder = new TracerProviderBuilderHosting(services);
-            configure(builder);
-            return services.AddOpenTelemetryTracing(sp => builder.Build(sp));
+            services.ConfigureOpenTelemetryTracing(configure);
+
+            services.TryAddEnumerable(ServiceDescriptor.Singleton<IHostedService, TelemetryHostedService>());
+
+            return services;
         }
 
         /// <summary>
@@ -81,34 +91,6 @@ public static IServiceCollection AddOpenTelemetryMetrics(this IServiceCollection
             return services.AddOpenTelemetryMetrics(sp => builder.Build(sp));
         }
 
-        /// <summary>
-        /// Adds OpenTelemetry TracerProvider to the specified <see cref="IServiceCollection" />.
-        /// </summary>
-        /// <param name="services">The <see cref="IServiceCollection" /> to add services to.</param>
-        /// <param name="createTracerProvider">A delegate that provides the tracer provider to be registered.</param>
-        /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns>
-        private static IServiceCollection AddOpenTelemetryTracing(this IServiceCollection services, Func<IServiceProvider, TracerProvider> createTracerProvider)
-        {
-            Guard.ThrowIfNull(services);
-            Guard.ThrowIfNull(createTracerProvider);
-
-            // Accessing Sdk class is just to trigger its static ctor,
-            // which sets default Propagators and default Activity Id format
-            _ = Sdk.SuppressInstrumentation;
-
-            try
-            {
-                services.TryAddEnumerable(ServiceDescriptor.Singleton<IHostedService, TelemetryHostedService>());
-                return services.AddSingleton(s => createTracerProvider(s));
-            }
-            catch (Exception ex)
-            {
-                HostingExtensionsEventSource.Log.FailedInitialize(ex);
-            }
-
-            return services;
-        }
-
         /// <summary>
         /// Adds OpenTelemetry MeterProvider to the specified <see cref="IServiceCollection" />.
         /// </summary>

src/OpenTelemetry.Extensions.Hosting/README.md

@@ -45,27 +45,27 @@ Similar methods exist for registering instrumentation (`AddInstrumentation<T>`)
 and setting a sampler (`SetSampler<T>`).
 
 You can also access the application `IServiceProvider` directly and accomplish
-the same registration using the `Configure` extension like this:
+the same registration using the `ConfigureBuilder` extension like this:
 
 ```csharp
 services.AddSingleton<MyProcessor>();
 
 services.AddOpenTelemetryTracing(hostingBuilder => hostingBuilder
-    .Configure((sp, builder) => builder
+    .ConfigureBuilder((sp, builder) => builder
         .AddAspNetCoreInstrumentation()
         .AddHttpClientInstrumentation()
         .AddProcessor(sp.GetRequiredService<MyProcessor>())));
 ```
 
-**Note:** `Configure` is called _after_ the `IServiceProvider` has been built
+**Note:** `ConfigureBuilder` is called _after_ the `IServiceProvider` has been built
 from the application `IServiceCollection` so any services registered in the
-`Configure` callback will be ignored.
+`ConfigureBuilder` callback will be ignored.
 
 #### Building Extension Methods
 
 Library authors may want to configure the OpenTelemetry `TracerProvider` and
 register application services to provide more complex features. This can be
-accomplished concisely by using the `TracerProviderBuilder.GetServices`
+accomplished concisely by using the `TracerProviderBuilder.ConfigureServices`
 extension method inside of a more general `TracerProviderBuilder` configuration
 extension like this:
 
@@ -74,15 +74,13 @@ public static class MyLibraryExtensions
 {
     public static TracerProviderBuilder AddMyFeature(this TracerProviderBuilder tracerProviderBuilder)
     {
-        (tracerProviderBuilder.GetServices()
-            ?? throw new NotSupportedException(
-                "MyFeature requires a hosting TracerProviderBuilder instance."))
-            .AddHostedService<MyHostedService>()
-            .AddSingleton<MyService>()
-            .AddSingleton<MyProcessor>()
-            .AddSingleton<MySampler>();
-
         return tracerProviderBuilder
+            .ConfigureServices(services =>
+                services
+                    .AddHostedService<MyHostedService>()
+                    .AddSingleton<MyService>()
+                    .AddSingleton<MyProcessor>()
+                    .AddSingleton<MySampler>())
             .AddProcessor<MyProcessor>()
             .SetSampler<MySampler>();
     }