Add GlobalPropagators API and have instrumentation default to it

examples/MicroserviceExample/Utils/Messaging/MessageSender.cs

@@ -28,7 +28,7 @@ namespace Utils.Messaging
     public class MessageSender : IDisposable
     {
         private static readonly ActivitySource ActivitySource = new ActivitySource(nameof(MessageSender));
-        private static readonly TextMapPropagator Propagator = new TraceContextPropagator();
+        private static readonly TextMapPropagator Propagator = Propagators.DefaultTextMapPropagator;
 
         private readonly ILogger<MessageSender> logger;
         private readonly IConnection connection;

src/OpenTelemetry.Api/CHANGELOG.md

@@ -15,6 +15,8 @@
   to CompositeTextMapPropagator. IPropagator is renamed to TextMapPropagator
   and changed from interface to abstract class.
   ([#1427](https://github.com/open-telemetry/opentelemetry-dotnet/pull/1427))
+* Added GlobalPropagators API via Propagators.DefaultTextMapPropagator.
+  ([#1427](https://github.com/open-telemetry/opentelemetry-dotnet/pull/1428))
 
 ## 0.7.0-beta.1
 

src/OpenTelemetry.Api/Context/Propagation/NoopTextMapPropagator.cs

@@ -0,0 +1,37 @@
+// <copyright file="NoopTextMapPropagator.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;
+using System.Collections.Generic;
+
+namespace OpenTelemetry.Context.Propagation
+{
+    internal class NoopTextMapPropagator : TextMapPropagator
+    {
+        private static readonly PropagationContext DefaultPropagationContext = default;
+
+        public override ISet<string> Fields => null;
+
+        public override PropagationContext Extract<T>(PropagationContext context, T carrier, Func<T, string, IEnumerable<string>> getter)
+        {
+            return DefaultPropagationContext;
+        }
+
+        public override void Inject<T>(PropagationContext context, T carrier, Action<T, string, string> setter)
+        {
+        }
+    }
+}

src/OpenTelemetry.Api/Context/Propagation/Propagators.cs

@@ -0,0 +1,36 @@
+// <copyright file="Propagators.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>
+
+namespace OpenTelemetry.Context.Propagation
+{
+    /// <summary>
+    /// Propagators allow setting the global default Propagators.
+    /// </summary>
+    public static class Propagators
+    {
+        private static readonly TextMapPropagator Noop = new NoopTextMapPropagator();
+
+        /// <summary>
+        /// Gets or sets the Default TextMapPropagator to be used.
+        /// </summary>
+        public static TextMapPropagator DefaultTextMapPropagator { get; set; } = Noop;
+
+        internal static void Reset()
+        {
+            DefaultTextMapPropagator = Noop;
+        }
+    }
+}

src/OpenTelemetry.Instrumentation.AspNet/AspNetInstrumentationOptions.cs

@@ -27,13 +27,10 @@ namespace OpenTelemetry.Instrumentation.AspNet
     public class AspNetInstrumentationOptions
     {
         /// <summary>
-        /// Gets or sets <see cref="TextMapPropagator"/> for context propagation. Default value: <see cref="CompositeTextMapPropagator"/> with <see cref="TraceContextPropagator"/> &amp; <see cref="BaggagePropagator"/>.
+        /// Gets or sets <see cref="TextMapPropagator"/> for context propagation.
+        /// By default, <see cref="Propagators.DefaultTextMapPropagator" /> will be used.
         /// </summary>
-        public TextMapPropagator Propagator { get; set; } = new CompositeTextMapPropagator(new TextMapPropagator[]
-        {
-            new TraceContextPropagator(),
-            new BaggagePropagator(),
-        });
+        public TextMapPropagator Propagator { get; set; } = Propagators.DefaultTextMapPropagator;
 
         /// <summary>
         /// Gets or sets a Filter function to filter instrumentation for requests on a per request basis.

src/OpenTelemetry.Instrumentation.AspNet/CHANGELOG.md

@@ -6,6 +6,8 @@
   to CompositeTextMapPropagator. IPropagator is renamed to TextMapPropagator
   and changed from interface to abstract class.
   ([#1427](https://github.com/open-telemetry/opentelemetry-dotnet/pull/1427))
+* Propagators.DefaultTextMapPropagator will be used as the default Propagator
+  ([#1427](https://github.com/open-telemetry/opentelemetry-dotnet/pull/1428))
 
 ## 0.7.0-beta.1
 

src/OpenTelemetry.Instrumentation.AspNetCore/AspNetCoreInstrumentationOptions.cs

@@ -27,13 +27,10 @@ namespace OpenTelemetry.Instrumentation.AspNetCore
     public class AspNetCoreInstrumentationOptions
     {
         /// <summary>
-        /// Gets or sets <see cref="TextMapPropagator"/> for context propagation. Default value: <see cref="CompositeTextMapPropagator"/> with <see cref="TraceContextPropagator"/> &amp; <see cref="BaggagePropagator"/>.
+        /// Gets or sets <see cref="TextMapPropagator"/> for context propagation.
+        /// By default, <see cref="Propagators.DefaultTextMapPropagator" /> will be used.
         /// </summary>
-        public TextMapPropagator Propagator { get; set; } = new CompositeTextMapPropagator(new TextMapPropagator[]
-        {
-            new TraceContextPropagator(),
-            new BaggagePropagator(),
-        });
+        public TextMapPropagator Propagator { get; set; } = Propagators.DefaultTextMapPropagator;
 
         /// <summary>
         /// Gets or sets a Filter function to filter instrumentation for requests on a per request basis.

src/OpenTelemetry.Instrumentation.AspNetCore/CHANGELOG.md

@@ -14,6 +14,8 @@
   to CompositeTextMapPropagator. IPropagator is renamed to TextMapPropagator
   and changed from interface to abstract class.
   ([#1427](https://github.com/open-telemetry/opentelemetry-dotnet/pull/1427))
+* Propagators.DefaultTextMapPropagator will be used as the default Propagator
+  ([#1427](https://github.com/open-telemetry/opentelemetry-dotnet/pull/1428))
 
 ## 0.7.0-beta.1
 

src/OpenTelemetry.Instrumentation.Http/CHANGELOG.md

@@ -10,6 +10,8 @@
   to CompositeTextMapPropagator. IPropagator is renamed to TextMapPropagator
   and changed from interface to abstract class.
   ([#1427](https://github.com/open-telemetry/opentelemetry-dotnet/pull/1427))
+* Propagators.DefaultTextMapPropagator will be used as the default Propagator
+  ([#1427](https://github.com/open-telemetry/opentelemetry-dotnet/pull/1428))
 
 ## 0.7.0-beta.1
 

src/OpenTelemetry.Instrumentation.Http/HttpClientInstrumentationOptions.cs

@@ -35,13 +35,10 @@ public class HttpClientInstrumentationOptions
         public bool SetHttpFlavor { get; set; }
 
         /// <summary>
-        /// Gets or sets <see cref="TextMapPropagator"/> for context propagation. Default value: <see cref="CompositeTextMapPropagator"/> with <see cref="TraceContextPropagator"/> &amp; <see cref="BaggagePropagator"/>.
+        /// Gets or sets <see cref="TextMapPropagator"/> for context propagation.
+        /// By default, <see cref="Propagators.DefaultTextMapPropagator" /> will be used.
         /// </summary>
-        public TextMapPropagator Propagator { get; set; } = new CompositeTextMapPropagator(new TextMapPropagator[]
-        {
-            new TraceContextPropagator(),
-            new BaggagePropagator(),
-        });
+        public TextMapPropagator Propagator { get; set; } = Propagators.DefaultTextMapPropagator;
 
         /// <summary>
         /// Gets or sets a Filter function to filter instrumentation for requests on a per request basis.

src/OpenTelemetry/Logs/OpenTelemetryLoggerProvider.cs

@@ -31,6 +31,13 @@ public class OpenTelemetryLoggerProvider : ILoggerProvider, ISupportExternalScop
         private bool disposed;
         private IExternalScopeProvider scopeProvider;
 
+        static OpenTelemetryLoggerProvider()
+        {
+            // Accessing Sdk class is just to trigger its static ctor,
+            // which sets default Propagators and default Activity Id format
+            _ = Sdk.SuppressInstrumentation;
+        }
+
         public OpenTelemetryLoggerProvider(IOptionsMonitor<OpenTelemetryLoggerOptions> options)
             : this(options?.CurrentValue)
         {

src/OpenTelemetry/Sdk.cs

@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+using System.Diagnostics;
+using OpenTelemetry.Context.Propagation;
 using OpenTelemetry.Metrics;
 using OpenTelemetry.Trace;
 
@@ -24,6 +26,18 @@ namespace OpenTelemetry
     /// </summary>
     public static class Sdk
     {
+        static Sdk()
+        {
+            Propagators.DefaultTextMapPropagator = new CompositeTextMapPropagator(new TextMapPropagator[]
+            {
+                new TraceContextPropagator(),
+                new BaggagePropagator(),
+            });
+
+            Activity.DefaultIdFormat = ActivityIdFormat.W3C;
+            Activity.ForceDefaultIdFormat = true;
+        }
+
         /// <summary>
         /// Gets a value indicating whether instrumentation is suppressed (disabled).
         /// </summary>

src/OpenTelemetry/Trace/TracerProviderSdk.cs

@@ -34,12 +34,6 @@ internal class TracerProviderSdk : TracerProvider
         private readonly ActivitySourceAdapter adapter;
         private BaseProcessor<Activity> processor;
 
-        static TracerProviderSdk()
-        {
-            Activity.DefaultIdFormat = ActivityIdFormat.W3C;
-            Activity.ForceDefaultIdFormat = true;
-        }
-
         internal TracerProviderSdk(
             Resource resource,
             IEnumerable<string> sources,

test/OpenTelemetry.Instrumentation.AspNetCore.Tests/BasicTests.cs

@@ -58,6 +58,21 @@ public void AddAspNetCoreInstrumentation_BadArgs()
             Assert.Throws<ArgumentNullException>(() => builder.AddAspNetCoreInstrumentation());
         }
 
+        [Fact]
+        public void DefaultPropagatorIsFromPropagators()
+        {
+            var options = new AspNetCoreInstrumentationOptions();
+            Assert.Same(Propagators.DefaultTextMapPropagator, options.Propagator);
+        }
+
+        [Fact]
+        public void PropagatorSetDoesNotAffectGlobalPropagators()
+        {
+            var options = new AspNetCoreInstrumentationOptions();
+            options.Propagator = new TraceContextPropagator();
+            Assert.NotSame(Propagators.DefaultTextMapPropagator, options.Propagator);
+        }
+
         [Fact]
         public async Task StatusIsUnsetOn200Response()
         {

test/OpenTelemetry.Tests/Context/PropagatorsTest.cs

@@ -0,0 +1,51 @@
+// <copyright file="PropagatorsTest.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;
+using OpenTelemetry.Context.Propagation;
+using OpenTelemetry.Context.Propagation.Tests;
+using Xunit;
+
+namespace OpenTelemetry.Context.Tests
+{
+    public class PropagatorsTest : IDisposable
+    {
+        public PropagatorsTest()
+        {
+            Propagators.Reset();
+        }
+
+        [Fact]
+        public void DefaultTextMapPropagatorIsNoop()
+        {
+            Assert.IsType<NoopTextMapPropagator>(Propagators.DefaultTextMapPropagator);
+            Assert.Same(Propagators.DefaultTextMapPropagator, Propagators.DefaultTextMapPropagator);
+        }
+
+        [Fact]
+        public void CanSetPropagator()
+        {
+            var testPropagator = new TestPropagator(string.Empty, string.Empty);
+            Propagators.DefaultTextMapPropagator = testPropagator;
+            Assert.Same(testPropagator, Propagators.DefaultTextMapPropagator);
+        }
+
+        public void Dispose()
+        {
+            Propagators.Reset();
+        }
+    }
+}