Extensibility prototype (#129)

* First prototype

* Use plugin manager to organize plugin loading. Add possibility to load multiple plugins.

* PR cleanup and fixes

* Fix plugin file name loading

* Fix vendoring sample references

* Fix comments

* refactor and add logging

* Fix plugin load logging

* Refactor plugins passing to tracer

* remove static property

* PR fixes and tests

* Refactor extendability points loading

* Refactor plugin with target framework loading

* Flatten propagators extension point

* Add logging for plugin config parsing error and fix comment

* Refactor composite propagator

Datadog.Trace.sln

@@ -33,13 +33,13 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution
 		.gitattributes = .gitattributes
 		.gitignore = .gitignore
 		Datadog.Trace.proj = Datadog.Trace.proj
-		OpenTelemetry.AutoInstrumentation.snk = OpenTelemetry.AutoInstrumentation.snk
 		Directory.Build.props = Directory.Build.props
 		docker-compose.yml = docker-compose.yml
 		GlobalSuppressions.cs = GlobalSuppressions.cs
 		integrations.json = integrations.json
 		LICENSE = LICENSE
 		LICENSE-3rdparty.csv = LICENSE-3rdparty.csv
+		OpenTelemetry.AutoInstrumentation.snk = OpenTelemetry.AutoInstrumentation.snk
 		docs\README.md = docs\README.md
 		stylecop.json = stylecop.json
 	EndProjectSection
@@ -428,7 +428,9 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "crank", "crank", "{E3FB283A
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "DuplicateTypeProxy", "test\test-applications\regression\DuplicateTypeProxy\DuplicateTypeProxy.csproj", "{34B67004-7249-4EF1-8E12-6E6DA37EA6BE}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Samples.AspNetCoreRazorPages", "test\test-applications\integrations\Samples.AspNetCoreRazorPages\Samples.AspNetCoreRazorPages.csproj", "{1B9E6BF4-9D48-4988-9945-248096119E46}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Samples.AspNetCoreRazorPages", "test\test-applications\integrations\Samples.AspNetCoreRazorPages\Samples.AspNetCoreRazorPages.csproj", "{1B9E6BF4-9D48-4988-9945-248096119E46}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Samples.Vendoring", "test\test-applications\integrations\Samples.Vendoring\Samples.Vendoring.csproj", "{0D4ACA4A-44DC-4603-8992-926B5BED5D76}"
 EndProject
 Global
 	GlobalSection(SharedMSBuildProjectFiles) = preSolution
@@ -1590,18 +1592,28 @@ Global
 		{34B67004-7249-4EF1-8E12-6E6DA37EA6BE}.Release|x64.Build.0 = Release|x64
 		{34B67004-7249-4EF1-8E12-6E6DA37EA6BE}.Release|x86.ActiveCfg = Release|x86
 		{34B67004-7249-4EF1-8E12-6E6DA37EA6BE}.Release|x86.Build.0 = Release|x86
-		{1B9E6BF4-9D48-4988-9945-248096119E46}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{1B9E6BF4-9D48-4988-9945-248096119E46}.Release|Any CPU.Build.0 = Release|Any CPU
 		{1B9E6BF4-9D48-4988-9945-248096119E46}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{1B9E6BF4-9D48-4988-9945-248096119E46}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{1B9E6BF4-9D48-4988-9945-248096119E46}.Debug|x64.ActiveCfg = Debug|Any CPU
 		{1B9E6BF4-9D48-4988-9945-248096119E46}.Debug|x64.Build.0 = Debug|Any CPU
 		{1B9E6BF4-9D48-4988-9945-248096119E46}.Debug|x86.ActiveCfg = Debug|Any CPU
 		{1B9E6BF4-9D48-4988-9945-248096119E46}.Debug|x86.Build.0 = Debug|Any CPU
+		{1B9E6BF4-9D48-4988-9945-248096119E46}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{1B9E6BF4-9D48-4988-9945-248096119E46}.Release|Any CPU.Build.0 = Release|Any CPU
 		{1B9E6BF4-9D48-4988-9945-248096119E46}.Release|x64.ActiveCfg = Release|Any CPU
 		{1B9E6BF4-9D48-4988-9945-248096119E46}.Release|x64.Build.0 = Release|Any CPU
 		{1B9E6BF4-9D48-4988-9945-248096119E46}.Release|x86.ActiveCfg = Release|Any CPU
 		{1B9E6BF4-9D48-4988-9945-248096119E46}.Release|x86.Build.0 = Release|Any CPU
+		{0D4ACA4A-44DC-4603-8992-926B5BED5D76}.Debug|Any CPU.ActiveCfg = Debug|x86
+		{0D4ACA4A-44DC-4603-8992-926B5BED5D76}.Debug|x64.ActiveCfg = Debug|x64
+		{0D4ACA4A-44DC-4603-8992-926B5BED5D76}.Debug|x64.Build.0 = Debug|x64
+		{0D4ACA4A-44DC-4603-8992-926B5BED5D76}.Debug|x86.ActiveCfg = Debug|x86
+		{0D4ACA4A-44DC-4603-8992-926B5BED5D76}.Debug|x86.Build.0 = Debug|x86
+		{0D4ACA4A-44DC-4603-8992-926B5BED5D76}.Release|Any CPU.ActiveCfg = Release|x86
+		{0D4ACA4A-44DC-4603-8992-926B5BED5D76}.Release|x64.ActiveCfg = Release|x64
+		{0D4ACA4A-44DC-4603-8992-926B5BED5D76}.Release|x64.Build.0 = Release|x64
+		{0D4ACA4A-44DC-4603-8992-926B5BED5D76}.Release|x86.ActiveCfg = Release|x86
+		{0D4ACA4A-44DC-4603-8992-926B5BED5D76}.Release|x86.Build.0 = Release|x86
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -1727,6 +1739,7 @@ Global
 		{E3FB283A-B766-4887-95E1-329667671921} = {A0C5FBBB-CFB2-4FB9-B8F0-55676E9DCF06}
 		{34B67004-7249-4EF1-8E12-6E6DA37EA6BE} = {498A300E-D036-49B7-A43D-821D1CAF11A5}
 		{1B9E6BF4-9D48-4988-9945-248096119E46} = {BAF8F246-3645-42AD-B1D0-0F7EAFBAB34A}
+		{0D4ACA4A-44DC-4603-8992-926B5BED5D76} = {BAF8F246-3645-42AD-B1D0-0F7EAFBAB34A}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {160A1D00-1F5B-40F8-A155-621B4459D78F}

src/Datadog.Trace.ClrProfiler.Managed/Instrumentation.cs

@@ -4,6 +4,7 @@
 using Datadog.Trace.Configuration;
 using Datadog.Trace.DiagnosticListeners;
 using Datadog.Trace.Logging;
+using Datadog.Trace.Plugins;
 using Datadog.Trace.ServiceFabric;
 
 namespace Datadog.Trace.ClrProfiler
@@ -59,8 +60,11 @@ public static void Initialize()
 
             try
             {
-                // ensure global instance is created if it's not already
-                _ = Tracer.Instance;
+                // Creates GlobalSettings instance and loads plugins
+                var plugins = PluginManager.TryLoadPlugins(GlobalSettings.Source.PluginsConfiguration);
+
+                // First call to create Tracer instace
+                Tracer.Instance = new Tracer(plugins);
             }
             catch
             {

src/Datadog.Trace/Configuration/ConfigurationKeys.cs

@@ -12,6 +12,11 @@ public static class ConfigurationKeys
         /// </summary>
         public const string ConfigurationFileName = "OTEL_TRACE_CONFIG_FILE";
 
+        /// <summary>
+        /// Configuration key for the path to the plugins configuration file.
+        /// </summary>
+        public const string PluginConfigurationFileName = "OTEL_DOTNET_TRACER_PLUGINS_FILE";
+
         /// <summary>
         /// Configuration key for the application's environment. Sets the "env" tag on every <see cref="Span"/>.
         /// </summary>

src/Datadog.Trace/Configuration/GlobalSettings.cs

@@ -32,6 +32,11 @@ internal GlobalSettings(IConfigurationSource source)
             DiagnosticSourceEnabled = source?.GetBool(ConfigurationKeys.DiagnosticSourceEnabled) ??
                                       // default value
                                       true;
+
+            if (TryLoadPluginJsonConfigurationFile(source, out JsonConfigurationSource jsonConfigurationSource))
+            {
+                PluginsConfiguration = jsonConfigurationSource;
+            }
         }
 
         /// <summary>
@@ -55,6 +60,11 @@ internal GlobalSettings(IConfigurationSource source)
         /// </summary>
         internal bool DiagnosticSourceEnabled { get; }
 
+        /// <summary>
+        /// Gets the plugins configuration.
+        /// </summary>
+        internal JsonConfigurationSource PluginsConfiguration { get; }
+
         /// <summary>
         /// Set whether debug mode is enabled.
         /// Affects the level of logs written to file.
@@ -121,15 +131,28 @@ internal static CompositeConfigurationSource CreateDefaultConfigurationSource()
             return configurationSource;
         }
 
-        private static bool TryLoadJsonConfigurationFile(IConfigurationSource configurationSource, out IConfigurationSource jsonConfigurationSource)
+        private static bool TryLoadPluginJsonConfigurationFile(IConfigurationSource configurationSource, out JsonConfigurationSource jsonConfigurationSource)
+        {
+            var configurationFileName = configurationSource?.GetString(ConfigurationKeys.PluginConfigurationFileName) ??
+                                        Path.Combine(GetCurrentDirectory(), "plugins.json");
+
+            return TryLoadJsonConfigurationFile(configurationFileName, out jsonConfigurationSource);
+        }
+
+        private static bool TryLoadJsonConfigurationFile(IConfigurationSource configurationSource, out JsonConfigurationSource jsonConfigurationSource)
+        {
+            // if environment variable is not set, look for default file name in the current directory
+            var configurationFileName = configurationSource.GetString(ConfigurationKeys.ConfigurationFileName) ??
+                                        configurationSource.GetString("OTEL_DOTNET_TRACER_CONFIG_FILE") ??
+                                        Path.Combine(GetCurrentDirectory(), "datadog.json");
+
+            return TryLoadJsonConfigurationFile(configurationFileName, out jsonConfigurationSource);
+        }
+
+        private static bool TryLoadJsonConfigurationFile(string configurationFileName, out JsonConfigurationSource jsonConfigurationSource)
         {
             try
             {
-                // if environment variable is not set, look for default file name in the current directory
-                var configurationFileName = configurationSource.GetString(ConfigurationKeys.ConfigurationFileName) ??
-                                            configurationSource.GetString("OTEL_DOTNET_TRACER_CONFIG_FILE") ??
-                                            Path.Combine(GetCurrentDirectory(), "datadog.json");
-
                 if (string.Equals(Path.GetExtension(configurationFileName), ".JSON", StringComparison.OrdinalIgnoreCase) &&
                     File.Exists(configurationFileName))
                 {

src/Datadog.Trace/Configuration/JsonConfigurationSource.cs

@@ -145,6 +145,15 @@ public IDictionary<string, string> GetDictionary(string key, bool allowOptionalM
             return GetDictionaryInternal(key, allowOptionalMappings);
         }
 
+        /// <summary>
+        /// Gets the string representation of json config.
+        /// </summary>
+        /// <returns>String format.</returns>
+        public override string ToString()
+        {
+            return _configuration.ToString();
+        }
+
         private IDictionary<string, string> GetDictionaryInternal(string key, bool allowOptionalMappings)
         {
             var token = _configuration.SelectToken(key, errorWhenNoMatch: false);

src/Datadog.Trace/Configuration/TracerSettings.cs

@@ -3,6 +3,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Text.RegularExpressions;
+using Datadog.Trace.Configuration.Types;
 using Datadog.Trace.ExtensionMethods;
 using Datadog.Trace.PlatformHelpers;
 using Datadog.Trace.Util;
@@ -369,7 +370,7 @@ public TracerSettings(IConfigurationSource source)
         /// Default is <c>Datadog</c>
         /// <seealso cref="ConfigurationKeys.Propagators"/>
         /// </summary>
-        public HashSet<PropagatorType> Propagators { get; set; }
+        public HashSet<string> Propagators { get; set; }
 
         /// <summary>
         /// Gets or sets a value indicating whether runtime metrics
@@ -640,18 +641,18 @@ internal string GetServiceName(Tracer tracer, string serviceName)
             return ServiceNameMappings.GetServiceName(tracer.DefaultServiceName, serviceName);
         }
 
-        private static HashSet<PropagatorType> GetPropagators(IConfigurationSource source)
+        private static HashSet<string> GetPropagators(IConfigurationSource source)
         {
-            var propagators = source.GetTypedValues<PropagatorType>(ConfigurationKeys.Propagators);
+            var propagators = source.GetStrings(ConfigurationKeys.Propagators);
 
             if (!propagators.Any())
             {
                 // TODO: Default to W3C (be aware of integration tests)
                 // see more: https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/context/api-propagators.md#global-propagators
-                return new HashSet<PropagatorType>() { PropagatorType.Datadog };
+                return new HashSet<string>() { PropagatorTypes.Datadog };
             }
 
-            return new HashSet<PropagatorType>(propagators);
+            return new HashSet<string>(propagators);
         }
     }
 }

src/Datadog.Trace/Configuration/Types/PropagatorTypes.cs

@@ -0,0 +1,23 @@
+namespace Datadog.Trace.Configuration.Types
+{
+    /// <summary>
+    /// Contains default available propagator types.
+    /// </summary>
+    public static class PropagatorTypes
+    {
+        /// <summary>
+        /// The Datadog propagator.
+        /// </summary>
+        public const string Datadog = "Datadog";
+
+        /// <summary>
+        /// The B3 propagator
+        /// </summary>
+        public const string B3 = "B3";
+
+        /// <summary>
+        /// The W3C propagator
+        /// </summary>
+        public const string W3C = "W3C";
+    }
+}

src/Datadog.Trace/Conventions/ITraceIdConvention.cs

@@ -3,10 +3,19 @@ namespace Datadog.Trace.Conventions
     /// <summary>
     /// Convention used when defining format of TraceId.
     /// </summary>
-    internal interface ITraceIdConvention
+    public interface ITraceIdConvention
     {
+        /// <summary>
+        /// Generates new unique trace id based on convention.
+        /// </summary>
+        /// <returns>Trace id.</returns>
         TraceId GenerateNewTraceId();
 
+        /// <summary>
+        /// Creates new trace id based on given string.
+        /// </summary>
+        /// <param name="id">String of id.</param>
+        /// <returns>Trace id.</returns>
         TraceId CreateFromString(string id);
     }
 }

src/Datadog.Trace/FrameworkDescription.cs

@@ -1,10 +1,8 @@
 using System;
-using System.Linq;
+using System.Collections.Generic;
 using System.Reflection;
-using System.Runtime.InteropServices;
-using System.Text.RegularExpressions;
+using System.Runtime.Versioning;
 using Datadog.Trace.Logging;
-using Microsoft.Win32;
 
 namespace Datadog.Trace
 {
@@ -29,6 +27,15 @@ internal partial class FrameworkDescription
             Tuple.Create(378389, "4.5"),
         };
 
+        private static readonly IReadOnlyDictionary<string, string> TargetFrameworkMapping = new Dictionary<string, string>()
+        {
+            { ".NETFramework,Version=v4.5", "net45" },
+            { ".NETFramework,Version=v4.6.1", "net461" },
+            { ".NETStandard,Version=v2.0", "netstandard2.0" },
+            { ".NETCoreApp,Version=v3.1", "netcoreapp3.1" },
+            { ".NETCoreApp,Version=v5.0", "net50" }
+        };
+
         private FrameworkDescription(
             string name,
             string productVersion,
@@ -41,6 +48,7 @@ private FrameworkDescription(
             OSPlatform = osPlatform;
             OSArchitecture = osArchitecture;
             ProcessArchitecture = processArchitecture;
+            TargetFramework = GetTargetFramework();
         }
 
         public string Name { get; }
@@ -53,6 +61,8 @@ private FrameworkDescription(
 
         public string ProcessArchitecture { get; }
 
+        public string TargetFramework { get; }
+
         public override string ToString()
         {
             // examples:
@@ -61,6 +71,20 @@ public override string ToString()
             return $"{Name} {ProductVersion} {ProcessArchitecture} on {OSPlatform} {OSArchitecture}";
         }
 
+        private static string GetTargetFramework()
+        {
+            var framework = typeof(FrameworkDescription).Assembly
+                .GetCustomAttribute<TargetFrameworkAttribute>()?
+                .FrameworkName;
+
+            if (!TargetFrameworkMapping.TryGetValue(framework, out string targetFramework))
+            {
+                throw new InvalidOperationException($"Target framework mapping is not defined for '{framework}'");
+            }
+
+            return targetFramework;
+        }
+
         private static string GetVersionFromAssemblyAttributes()
         {
             string productVersion = null;

src/Datadog.Trace/Plugins/IOTelExtension.cs

@@ -0,0 +1,9 @@
+namespace Datadog.Trace.Plugins
+{
+    /// <summary>
+    /// Base marker interface for extendability points.
+    /// </summary>
+    public interface IOTelExtension
+    {
+    }
+}