Introduce support for distributed tracing and Open Telemetry

EventStore.Client.sln

@@ -33,6 +33,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "EventStore.Client.UserManag
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "EventStore.Client.Tests.Common", "test\EventStore.Client.Tests.Common\EventStore.Client.Tests.Common.csproj", "{E326832D-DE52-4DE4-9E54-C800908B75F3}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "EventStore.Client.Extensions.OpenTelemetry", "src\EventStore.Client.Extensions.OpenTelemetry\EventStore.Client.Extensions.OpenTelemetry.csproj", "{3723933C-585A-49BE-98E8-52D3FAD904CE}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|x64 = Debug|x64
@@ -94,6 +96,10 @@ Global
 		{E326832D-DE52-4DE4-9E54-C800908B75F3}.Debug|x64.Build.0 = Debug|Any CPU
 		{E326832D-DE52-4DE4-9E54-C800908B75F3}.Release|x64.ActiveCfg = Release|Any CPU
 		{E326832D-DE52-4DE4-9E54-C800908B75F3}.Release|x64.Build.0 = Release|Any CPU
+		{3723933C-585A-49BE-98E8-52D3FAD904CE}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{3723933C-585A-49BE-98E8-52D3FAD904CE}.Debug|x64.Build.0 = Debug|Any CPU
+		{3723933C-585A-49BE-98E8-52D3FAD904CE}.Release|x64.ActiveCfg = Release|Any CPU
+		{3723933C-585A-49BE-98E8-52D3FAD904CE}.Release|x64.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{D3744A86-DD35-4104-AAEE-84B79062C4A2} = {EA59C1CB-16DA-4F68-AF8A-642A969B4CF8}
@@ -109,5 +115,6 @@ Global
 		{6CEB731F-72E1-461F-A6B3-54DBF3FD786C} = {C51F2C69-45A9-4D0D-A708-4FC319D5D340}
 		{22634CEE-4F7B-4679-A48D-38A2A8580ECA} = {C51F2C69-45A9-4D0D-A708-4FC319D5D340}
 		{E326832D-DE52-4DE4-9E54-C800908B75F3} = {C51F2C69-45A9-4D0D-A708-4FC319D5D340}
+		{3723933C-585A-49BE-98E8-52D3FAD904CE} = {EA59C1CB-16DA-4F68-AF8A-642A969B4CF8}
 	EndGlobalSection
 EndGlobal

README.md

@@ -19,6 +19,14 @@ Reference the nuget package(s) for the API that you would like to call
 
 [User Management](https://www.nuget.org/packages/EventStore.Client.Grpc.UserManagement)
 
+## Open Telemetry
+
+Telemetry instrumentation can be enabled by installing the [Open Telemetry Extensions](https://www.nuget.org/packages/EventStore.Client.Extensions.OpenTelemetry) package.
+
+Once installed you can configure instrumentation using the `AddEventStoreClientInstrumentation` extension method on a `TracerProviderBuilder`.
+
+Tracing is the only telemetry currently exported, specifically for the `Append` and `Subscribe` (Catchup and Persistent) operations.
+
 ## Support
 
 Information on support and commercial tools such as LDAP authentication can be found here: [Event Store Support](https://eventstore.com/support/).

src/Directory.Build.props

@@ -4,7 +4,7 @@
         <RootNamespace>EventStore.Client</RootNamespace>
     </PropertyGroup>
 
-    <PropertyGroup Condition="$(MSBuildProjectName) != 'EventStore.Client'">
+    <PropertyGroup Condition="$(MSBuildProjectName) != 'EventStore.Client' And $(MSBuildProjectName) != 'EventStore.Client.Extensions.OpenTelemetry'">
         <ESPackageIdSuffix>$(MSBuildProjectName.Remove(0,18))</ESPackageIdSuffix>
         <ESProto>$(ESPackageIdSuffix.ToLower()).proto</ESProto>
         <ESProtoPath>../EventStore.Client.Common/protos/$(ESProto)</ESProtoPath>
@@ -50,6 +50,10 @@
         <Compile Include="../EventStore.Client.Common/**/*.cs" Link="Common\%(RecursiveDir)/%(FileName)%(Extension)"/>
     </ItemGroup>
 
+    <ItemGroup Condition="$(MSBuildProjectName) == 'EventStore.Client.Streams' Or $(MSBuildProjectName) == 'EventStore.Client.PersistentSubscriptions'">
+    	<Compile Include="../EventStore.Client/Diagnostics/**/*.cs" Link="Diagnostics\%(RecursiveDir)/%(FileName)%(Extension)"/>
+    </ItemGroup>
+
     <ItemGroup>
         <AssemblyAttribute Include="System.Runtime.CompilerServices.InternalsVisibleTo">
             <_Parameter1>$(ProjectName).Tests</_Parameter1>

src/EventStore.Client.Common/Constants.cs

@@ -39,10 +39,10 @@ public static class Exceptions {
 	}
 
 	public static class Metadata {
-		public const           string   Type             = "type";
-		public const           string   Created          = "created";
-		public const           string   ContentType      = "content-type";
-		public static readonly string[] RequiredMetadata = { Type, ContentType };
+		public const           string   Type               = "type";
+		public const           string   Created            = "created";
+		public const           string   ContentType        = "content-type";
+		public static readonly string[] RequiredMetadata   = { Type, ContentType };
 
 		public static class ContentTypes {
 			public const string ApplicationJson        = "application/json";
@@ -58,4 +58,4 @@ public static class Headers {
 		public const string ConnectionName = "connection-name";
 		public const string RequiresLeader = "requires-leader";
 	}
-}
+}

src/EventStore.Client.Extensions.OpenTelemetry/EventStore.Client.Extensions.OpenTelemetry.csproj

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project Sdk="Microsoft.NET.Sdk">
+	<PropertyGroup>
+		<RootNamespace>EventStore.Client.Extensions.OpenTelemetry</RootNamespace>
+	</PropertyGroup>
+
+	<PropertyGroup>
+		<PackageId>EventStore.Client.Extensions.OpenTelemetry</PackageId>
+		<Description>Extensions used to facilitate instrumentation of the EventStore Client.</Description>
+	</PropertyGroup>
+
+	<ItemGroup>
+	  <PackageReference Include="OpenTelemetry.Api" Version="1.8.0" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<Compile Include="../EventStore.Client/Diagnostics/EventStoreClientInstrumentation.cs" Link="%(FileName)%(Extension)"/>
+	</ItemGroup>
+
+</Project>

src/EventStore.Client.Extensions.OpenTelemetry/TracerProviderBuilderExtensions.cs

@@ -0,0 +1,19 @@
+using EventStore.Client.Diagnostics;
+using JetBrains.Annotations;
+using OpenTelemetry.Trace;
+
+namespace EventStore.Client.Extensions.OpenTelemetry;
+
+/// <summary>
+/// Extension methods used to facilitate instrumentation of the EventStore Client.
+/// </summary>
+[PublicAPI]
+public static class TracerProviderBuilderExtensions {
+	/// <summary>
+	/// Enables instrumentation of the EventStore .NET Client on the OpenTelemetry TracerProvider.
+	/// </summary>
+	/// <param name="builder"><see cref="TracerProviderBuilder"/> being configured.</param>
+	/// <returns>The instance of <see cref="TracerProviderBuilder"/> to chain configuration.</returns>
+	public static TracerProviderBuilder AddEventStoreClientInstrumentation(this TracerProviderBuilder builder)
+		=> builder.AddSource(EventStoreClientInstrumentation.ActivitySourceName);
+}