Revert [sdk] Use reflection and dynamic types to start providers

build/Common.props

@@ -37,8 +37,7 @@
     <MicrosoftCodeCoveragePkgVer>[17.4.1]</MicrosoftCodeCoveragePkgVer>
     <MicrosoftExtensionsDependencyInjectionPkgVer>[3.1.0,)</MicrosoftExtensionsDependencyInjectionPkgVer>
     <MicrosoftExtensionsDependencyInjectionAbstractionsPkgVer>$(MicrosoftExtensionsDependencyInjectionPkgVer)</MicrosoftExtensionsDependencyInjectionAbstractionsPkgVer>
-    <MicrosoftExtensionsHostingPkgVer>[2.1.0,)</MicrosoftExtensionsHostingPkgVer>
-    <MicrosoftExtensionsHostingAbstractionsPkgVer>$(MicrosoftExtensionsHostingPkgVer)</MicrosoftExtensionsHostingAbstractionsPkgVer>
+    <MicrosoftExtensionsHostingAbstractionsPkgVer>[2.1.0,)</MicrosoftExtensionsHostingAbstractionsPkgVer>
     <MicrosoftExtensionsLoggingPkgVer>[3.1.0,)</MicrosoftExtensionsLoggingPkgVer>
     <MicrosoftExtensionsLoggingConfigurationPkgVer>$(MicrosoftExtensionsLoggingPkgVer)</MicrosoftExtensionsLoggingConfigurationPkgVer>
     <MicrosoftExtensionsOptionsPkgVer>[3.1.0,)</MicrosoftExtensionsOptionsPkgVer>

docs/trace/getting-started-aspnetcore/Program.cs

@@ -27,7 +27,8 @@
         .AddService(serviceName: "OTel.NET Getting Started"))
     .WithTracing(builder => builder
         .AddAspNetCoreInstrumentation()
-        .AddConsoleExporter());
+        .AddConsoleExporter())
+    .StartWithHost();
 
 var app = appBuilder.Build();
 

docs/trace/getting-started-aspnetcore/getting-started-aspnetcore.csproj

@@ -8,6 +8,7 @@
 
   <ItemGroup>
     <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Exporter.Console\OpenTelemetry.Exporter.Console.csproj" />
+    <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Extensions.Hosting\OpenTelemetry.Extensions.Hosting.csproj" />
     <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Instrumentation.AspNetCore\OpenTelemetry.Instrumentation.AspNetCore.csproj" />
   </ItemGroup>
 

examples/AspNetCore/Examples.AspNetCore.csproj

@@ -10,6 +10,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Extensions.Hosting\OpenTelemetry.Extensions.Hosting.csproj" />
     <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Exporter.Console\OpenTelemetry.Exporter.Console.csproj" />
     <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Exporter.OpenTelemetryProtocol\OpenTelemetry.Exporter.OpenTelemetryProtocol.csproj" />
     <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Exporter.OpenTelemetryProtocol.Logs\OpenTelemetry.Exporter.OpenTelemetryProtocol.Logs.csproj" />

examples/AspNetCore/Program.cs

@@ -44,7 +44,8 @@
 // for manual instrumentation
 appBuilder.Services.AddSingleton<Instrumentation>();
 
-// Configure OpenTelemetry tracing & metrics.
+// Configure OpenTelemetry tracing & metrics with auto-start using the
+// StartWithHost extension from OpenTelemetry.Extensions.Hosting.
 appBuilder.Services.AddOpenTelemetry()
     .ConfigureResource(configureResource)
     .WithTracing(builder =>
@@ -126,7 +127,8 @@
                 builder.AddConsoleExporter();
                 break;
         }
-    });
+    })
+    .StartWithHost();
 
 // Clear default logging providers used by WebApplication host.
 appBuilder.Logging.ClearProviders();

examples/GrpcService/Examples.GrpcService.csproj

@@ -16,6 +16,7 @@
     <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Exporter.Console\OpenTelemetry.Exporter.Console.csproj" />
     <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Exporter.Jaeger\OpenTelemetry.Exporter.Jaeger.csproj" />
     <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Exporter.Zipkin\OpenTelemetry.Exporter.Zipkin.csproj" />
+    <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Extensions.Hosting\OpenTelemetry.Extensions.Hosting.csproj" />
     <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Instrumentation.AspNetCore\OpenTelemetry.Instrumentation.AspNetCore.csproj" />
   </ItemGroup>
 

examples/GrpcService/Startup.cs

@@ -61,7 +61,8 @@ public void ConfigureServices(IServiceCollection services)
                             builder.AddConsoleExporter();
                             break;
                     }
-                });
+                })
+                .StartWithHost();
         }
 
         public void Configure(IApplicationBuilder app, IWebHostEnvironment env)

examples/MicroserviceExample/WebApi/Startup.cs

@@ -43,7 +43,8 @@ public void ConfigureServices(IServiceCollection services)
                     {
                         var zipkinHostName = Environment.GetEnvironmentVariable("ZIPKIN_HOSTNAME") ?? "localhost";
                         b.Endpoint = new Uri($"http://{zipkinHostName}:9411/api/v2/spans");
-                    }));
+                    }))
+                .StartWithHost();
         }
 
         public void Configure(IApplicationBuilder app, IWebHostEnvironment env)

examples/MicroserviceExample/WebApi/WebApi.csproj

@@ -10,6 +10,7 @@
   <ItemGroup>
     <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Instrumentation.AspNetCore\OpenTelemetry.Instrumentation.AspNetCore.csproj" />
     <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Exporter.Zipkin\OpenTelemetry.Exporter.Zipkin.csproj" />
+    <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Extensions.Hosting\OpenTelemetry.Extensions.Hosting.csproj" />
   </ItemGroup>
 
   <ItemGroup>

examples/MicroserviceExample/WorkerService/Program.cs

@@ -42,7 +42,8 @@ public static IHostBuilder CreateHostBuilder(string[] args) =>
                             {
                                 var zipkinHostName = Environment.GetEnvironmentVariable("ZIPKIN_HOSTNAME") ?? "localhost";
                                 b.Endpoint = new Uri($"http://{zipkinHostName}:9411/api/v2/spans");
-                            }));
+                            }))
+                        .StartWithHost();
                 });
     }
 }

examples/MicroserviceExample/WorkerService/WorkerService.csproj

@@ -11,6 +11,7 @@
   <ItemGroup>
     <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry\OpenTelemetry.csproj" />
     <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Exporter.Zipkin\OpenTelemetry.Exporter.Zipkin.csproj" />
+    <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Extensions.Hosting\OpenTelemetry.Extensions.Hosting.csproj" />
   </ItemGroup>
 
   <ItemGroup>

src/OpenTelemetry.Exporter.Jaeger/README.md

@@ -98,7 +98,8 @@ services.AddOpenTelemetry()
                 client.DefaultRequestHeaders.Add("X-MyCustomHeader", "value");
                 return client;
             };
-        }));
+        }))
+    .StartWithHost();
 ```
 
 For users using

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/README.md

@@ -135,7 +135,8 @@ services.AddOpenTelemetry()
                 client.DefaultRequestHeaders.Add("X-MyCustomHeader", "value");
                 return client;
             };
-        }));
+        }))
+    .StartWithHost();
 ```
 
 For users using

src/OpenTelemetry.Exporter.Prometheus.AspNetCore/README.md

@@ -28,7 +28,8 @@ dotnet add package --prerelease OpenTelemetry.Exporter.Prometheus.AspNetCore
     ```csharp
     services.AddOpenTelemetry()
         .WithMetrics(builder => builder
-            .AddPrometheusExporter());
+            .AddPrometheusExporter())
+        .StartWithHost();
     ```
 
 * Or configure directly:

src/OpenTelemetry.Exporter.Zipkin/README.md

@@ -87,7 +87,8 @@ services.AddOpenTelemetry()
             HttpClient client = new HttpClient();
             client.DefaultRequestHeaders.Add("X-MyCustomHeader", "value");
             return client;
-        }));
+        }))
+    .StartWithHost();
 ```
 
 For users using

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

@@ -1,11 +1,13 @@
 Microsoft.Extensions.DependencyInjection.OpenTelemetryServicesExtensions
 OpenTelemetry.Metrics.MeterProviderBuilderExtensions
+OpenTelemetry.OpenTelemetryBuilderHostingExtensions
 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
 static Microsoft.Extensions.DependencyInjection.OpenTelemetryServicesExtensions.AddOpenTelemetryTracing(this Microsoft.Extensions.DependencyInjection.IServiceCollection services, System.Action<OpenTelemetry.Trace.TracerProviderBuilder> configure) -> Microsoft.Extensions.DependencyInjection.IServiceCollection
 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.OpenTelemetryBuilderHostingExtensions.StartWithHost(this OpenTelemetry.OpenTelemetryBuilder builder) -> OpenTelemetry.OpenTelemetryBuilder
 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

src/OpenTelemetry.Extensions.Hosting/CHANGELOG.md

@@ -2,12 +2,6 @@
 
 ## Unreleased
 
-* Removed the `OpenTelemetryBuilder.StartWithHost` extension and moved the
-  functionality into the SDK `AddOpenTelemetry` extension. With this change
-  `OpenTelemetry.Extensions.Hosting` is no longer needed and will be marked as
-  deprecated.
-  ([#4151](https://github.com/open-telemetry/opentelemetry-dotnet/pull/4151))
-
 ## 1.4.0-rc.3
 
 Released 2023-Feb-01

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

@@ -0,0 +1,41 @@
+// <copyright file="HostingExtensionsEventSource.cs" company="OpenTelemetry Authors">
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+using System.Diagnostics.Tracing;
+
+namespace OpenTelemetry.Extensions.Hosting.Implementation
+{
+    /// <summary>
+    /// EventSource events emitted from the project.
+    /// </summary>
+    [EventSource(Name = "OpenTelemetry-Extensions-Hosting")]
+    internal sealed class HostingExtensionsEventSource : EventSource
+    {
+        public static HostingExtensionsEventSource Log = new();
+
+        [Event(1, Message = "OpenTelemetry TracerProvider was not found in application services. Tracing will remain disabled.", Level = EventLevel.Warning)]
+        public void TracerProviderNotRegistered()
+        {
+            this.WriteEvent(1);
+        }
+
+        [Event(2, Message = "OpenTelemetry MeterProvider was not found in application services. Metrics will remain disabled.", Level = EventLevel.Warning)]
+        public void MeterProviderNotRegistered()
+        {
+            this.WriteEvent(2);
+        }
+    }
+}

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

@@ -0,0 +1,64 @@
+// <copyright file="TelemetryHostedService.cs" company="OpenTelemetry Authors">
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+using System.Diagnostics;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using OpenTelemetry.Metrics;
+using OpenTelemetry.Trace;
+
+namespace OpenTelemetry.Extensions.Hosting.Implementation;
+
+internal sealed class TelemetryHostedService : IHostedService
+{
+    private readonly IServiceProvider serviceProvider;
+
+    public TelemetryHostedService(IServiceProvider serviceProvider)
+    {
+        this.serviceProvider = serviceProvider;
+    }
+
+    public Task StartAsync(CancellationToken cancellationToken)
+    {
+        // The sole purpose of this HostedService is to ensure all
+        // instrumentations, exporters, etc., are created and started.
+        Initialize(this.serviceProvider);
+
+        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>();
+        if (meterProvider == null)
+        {
+            HostingExtensionsEventSource.Log.MeterProviderNotRegistered();
+        }
+
+        var tracerProvider = serviceProvider.GetService<TracerProvider>();
+        if (tracerProvider == null)
+        {
+            HostingExtensionsEventSource.Log.TracerProviderNotRegistered();
+        }
+    }
+}

src/OpenTelemetry.Extensions.Hosting/OpenTelemetryBuilderHostingExtensions.cs

@@ -0,0 +1,54 @@
+// <copyright file="OpenTelemetryBuilderHostingExtensions.cs" company="OpenTelemetry Authors">
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+using Microsoft.Extensions.Hosting;
+using OpenTelemetry.Extensions.Hosting.Implementation;
+using OpenTelemetry.Internal;
+
+namespace OpenTelemetry;
+
+/// <summary>
+/// Contains hosting extension methods for the <see
+/// cref="OpenTelemetryBuilder"/> class.
+/// </summary>
+public static class OpenTelemetryBuilderHostingExtensions
+{
+    /// <summary>
+    /// Registers an <see cref="IHostedService"/> to automatically start all
+    /// configured OpenTelemetry services in the supplied <see
+    /// cref="IServiceCollection" />.
+    /// </summary>
+    /// <remarks>
+    /// Note: This is safe to be called multiple times. Only a single <see
+    /// cref="IHostedService"/> will be created for a given <see
+    /// cref="IServiceCollection"/>. This should generally be called by hosting
+    /// application code and NOT library authors.
+    /// </remarks>
+    /// <param name="builder"><see cref="OpenTelemetryBuilder"/>.</param>
+    /// <returns>The supplied <see cref="OpenTelemetryBuilder"/> for chaining
+    /// calls.</returns>
+    public static OpenTelemetryBuilder StartWithHost(this OpenTelemetryBuilder builder)
+    {
+        Guard.ThrowIfNull(builder);
+
+        builder.Services.TryAddEnumerable(
+            ServiceDescriptor.Singleton<IHostedService, TelemetryHostedService>());
+
+        return builder;
+    }
+}

src/OpenTelemetry.Extensions.Hosting/OpenTelemetryServicesExtensions.cs

@@ -51,7 +51,7 @@ public static class OpenTelemetryServicesExtensions
     /// <param name="services"><see cref="IServiceCollection"/>.</param>
     /// <returns>Supplied <see cref="IServiceCollection"/> for chaining
     /// calls.</returns>
-    [Obsolete("Use the AddOpenTelemetry().WithTracing(configure) pattern instead. This method will be removed in a future version.")]
+    [Obsolete("Use the AddOpenTelemetry().WithTracing(configure).StartWithHost() pattern instead. This method will be removed in a future version.")]
     public static IServiceCollection AddOpenTelemetryTracing(this IServiceCollection services)
         => AddOpenTelemetryTracing(services, b => { });
 
@@ -68,10 +68,10 @@ public static IServiceCollection AddOpenTelemetryTracing(this IServiceCollection
     /// cref="TracerProviderBuilder"/>.</param>
     /// <returns>Supplied <see cref="IServiceCollection"/> for chaining
     /// calls.</returns>
-    [Obsolete("Use the AddOpenTelemetry().WithTracing(configure) pattern instead. This method will be removed in a future version.")]
+    [Obsolete("Use the AddOpenTelemetry().WithTracing(configure).StartWithHost() pattern instead. This method will be removed in a future version.")]
     public static IServiceCollection AddOpenTelemetryTracing(this IServiceCollection services, Action<TracerProviderBuilder> configure)
     {
-        services.AddOpenTelemetry().WithTracing(configure);
+        services.AddOpenTelemetry().WithTracing(configure).StartWithHost();
 
         return services;
     }
@@ -100,7 +100,7 @@ public static IServiceCollection AddOpenTelemetryTracing(this IServiceCollection
     /// <param name="services"><see cref="IServiceCollection"/>.</param>
     /// <returns>Supplied <see cref="IServiceCollection"/> for chaining
     /// calls.</returns>
-    [Obsolete("Use the AddOpenTelemetry().WithMetrics(configure) pattern instead. This method will be removed in a future version.")]
+    [Obsolete("Use the AddOpenTelemetry().WithMetrics(configure).StartWithHost() pattern instead. This method will be removed in a future version.")]
     public static IServiceCollection AddOpenTelemetryMetrics(this IServiceCollection services)
         => AddOpenTelemetryMetrics(services, b => { });
 
@@ -117,10 +117,10 @@ public static IServiceCollection AddOpenTelemetryMetrics(this IServiceCollection
     /// cref="TracerProviderBuilder"/>.</param>
     /// <returns>Supplied <see cref="IServiceCollection"/> for chaining
     /// calls.</returns>
-    [Obsolete("Use the AddOpenTelemetry().WithMetrics(configure) pattern instead. This method will be removed in a future version.")]
+    [Obsolete("Use the AddOpenTelemetry().WithMetrics(configure).StartWithHost() pattern instead. This method will be removed in a future version.")]
     public static IServiceCollection AddOpenTelemetryMetrics(this IServiceCollection services, Action<MeterProviderBuilder> configure)
     {
-        services.AddOpenTelemetry().WithMetrics(configure);
+        services.AddOpenTelemetry().WithMetrics(configure).StartWithHost();
 
         return services;
     }