Introduce AgentBuilderOptions (#50)

* Introduce AgentBuilderOptions

Sadly we can not defer OltpExport to AgentBuilder.Build() in *all* IHostingEnvironments.

Atleast under WebApplicationHosts the IHostedLifecycleSerivce.StartingAsync happens on

app.Run() at which stage the IServiceCollection is marked as readonly.

To that end we now expose overloads to AddOpenTelemetry taking AgentBuilderOptions.

These are typically only needed for expert level control and not part of the documented getting started
approach.

This PR also addresses all warnings in the solution (branch started off for just that sorry!)

* remove recursive SkipOtlpRegistration extension method

* fix double logger initialization in logger tests

.editorconfig

@@ -191,6 +191,7 @@ resharper_csharp_accessor_owner_body=expression_body
 
 resharper_redundant_case_label_highlighting=do_not_show
 resharper_redundant_argument_default_value_highlighting=do_not_show
+resharper_explicit_caller_info_argument_highlighting=hint
 
 dotnet_diagnostic.IDE0057.severity = none
 

examples/Example.Elastic.OpenTelemetry.AspNetCore/Controllers/E2EController.cs

@@ -19,7 +19,7 @@ public async Task<IActionResult> Index()
 
 		await Task.Delay(100);
 
-		using var childActivity = activity?.Source.StartActivity("childActivity", ActivityKind.Internal);
+		using var childActivity = activity?.Source.StartActivity(ActivityKind.Internal);
 		await Task.Delay(200);
 
 		return View();
@@ -34,7 +34,7 @@ public async Task<IActionResult> Fail()
 
 		await Task.Delay(100);
 
-		using var childActivity = activity?.Source.StartActivity("childActivity", ActivityKind.Internal);
+		using var childActivity = activity?.Source.StartActivity(ActivityKind.Internal);
 		await Task.Delay(200);
 
 		throw new Exception("Random failure");

examples/Example.Elastic.OpenTelemetry.AspNetCore/Controllers/HomeController.cs

@@ -2,8 +2,8 @@
 // Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information
 using System.Diagnostics;
+using System.Net;
 using Example.Elastic.OpenTelemetry.AspNetCore.Models;
-using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Mvc;
 
 namespace Example.Elastic.OpenTelemetry.AspNetCore.Controllers;
@@ -17,19 +17,15 @@ public async Task<IActionResult> Index()
 	{
 		using var client = httpClientFactory.CreateClient();
 
-		var activityFeature = HttpContext.Features.Get<IHttpActivityFeature>();
-
+		// ReSharper disable once ExplicitCallerInfoArgument
 		using var activity = ActivitySource.StartActivity("DoingStuff", ActivityKind.Internal);
 		activity?.SetTag("CustomTag", "TagValue");
 
 		await Task.Delay(100);
 		var response = await client.GetAsync("http://elastic.co");
 		await Task.Delay(50);
 
-		if (response.StatusCode == System.Net.HttpStatusCode.OK)
-			activity?.SetStatus(ActivityStatusCode.Ok);
-		else
-			activity?.SetStatus(ActivityStatusCode.Error);
+		activity?.SetStatus(response.StatusCode == HttpStatusCode.OK ? ActivityStatusCode.Ok : ActivityStatusCode.Error);
 
 		return View();
 	}

examples/Example.Elastic.OpenTelemetry.Worker/Program.cs

@@ -2,7 +2,6 @@
 // Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information
 
-using Elastic.OpenTelemetry;
 using Example.Elastic.OpenTelemetry.Worker;
 using OpenTelemetry;
 using OpenTelemetry.Metrics;
@@ -11,13 +10,6 @@
 
 var builder = Host.CreateApplicationBuilder(args);
 
-/*
- * appBuilder.Services.AddOpenTelemetry()
-   .ConfigureResource(builder => builder.AddService(serviceName: "MyService"))
-   .WithTracing(builder => builder.AddConsoleExporter())
-   .WithMetrics(builder => builder.AddConsoleExporter());
- */
-
 builder.Services.AddElasticOpenTelemetry(Worker.ActivitySourceName, "CustomMeter")
 	.ConfigureResource(r => r.AddService(serviceName: "MyService"))
 	.WithTracing(t => t.AddConsoleExporter())

src/Elastic.OpenTelemetry/Agent.cs

@@ -30,7 +30,7 @@ private static string ParseAssemblyInformationalVersion(string? informationalVer
 		 * The following parts are optional: pre-release label, pre-release version, git height, Git SHA of current commit
 		 */
 
-		var indexOfPlusSign = informationalVersion!.IndexOf('+');
+		var indexOfPlusSign = informationalVersion.IndexOf('+');
 		return indexOfPlusSign > 0
 			? informationalVersion[..indexOfPlusSign]
 			: informationalVersion;

src/Elastic.OpenTelemetry/AgentBuilder.Build.cs

@@ -7,7 +7,6 @@
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using OpenTelemetry;
-using OpenTelemetry.Exporter;
 using OpenTelemetry.Metrics;
 using OpenTelemetry.Trace;
 
@@ -16,14 +15,6 @@ namespace Elastic.OpenTelemetry;
 /// <summary> TODO </summary>
 public static class OpenTelemetryBuilderExtensions
 {
-	/// <summary> TODO </summary>
-	public static IOpenTelemetryBuilder SkipOtlpExporter(this IOpenTelemetryBuilder builder)
-	{
-		if (builder is not AgentBuilder agentBuilder) return builder;
-
-		return agentBuilder.SkipOtlpExporter();
-	}
-
 	/// <summary> TODO </summary>
 	public static IOpenTelemetryBuilder WithLogger(this IOpenTelemetryBuilder builder, ILogger logger)
 	{
@@ -50,29 +41,6 @@ public static IAgent Build(this IOpenTelemetryBuilder builder, ILogger? logger =
 
 		log.SetAdditionalLogger(logger);
 
-		var openTelemetry =
-			Microsoft.Extensions.DependencyInjection.OpenTelemetryServicesExtensions.AddOpenTelemetry(agentBuilder.Services);
-
-		openTelemetry
-			.WithTracing(tracing =>
-			{
-				if (!agentBuilder.SkipOtlpRegistration)
-					tracing.AddOtlpExporter(agentBuilder.OtlpExporterName, agentBuilder.OtlpExporterConfiguration);
-				log.LogAgentBuilderBuiltTracerProvider();
-			})
-			.WithMetrics(metrics =>
-			{
-				if (!agentBuilder.SkipOtlpRegistration)
-				{
-					metrics.AddOtlpExporter(agentBuilder.OtlpExporterName, o =>
-					{
-						o.ExportProcessorType = ExportProcessorType.Simple;
-						o.Protocol = OtlpExportProtocol.HttpProtobuf;
-					});
-				}
-				log.LogAgentBuilderBuiltMeterProvider();
-			});
-
 		var sp = serviceProvider ?? agentBuilder.Services.BuildServiceProvider();
 		var tracerProvider = sp.GetService<TracerProvider>()!;
 		var meterProvider = sp.GetService<MeterProvider>()!;

src/Elastic.OpenTelemetry/AgentBuilder.cs

@@ -6,48 +6,83 @@
 using Elastic.OpenTelemetry.Diagnostics;
 using Elastic.OpenTelemetry.Diagnostics.Logging;
 using Elastic.OpenTelemetry.Extensions;
+using Elastic.OpenTelemetry.Hosting;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using OpenTelemetry;
 using OpenTelemetry.Exporter;
 using OpenTelemetry.Metrics;
-using OpenTelemetry.Resources;
 using OpenTelemetry.Trace;
 
 namespace Elastic.OpenTelemetry;
 
+
+/// <summary>
+/// Expert options to provide to <see cref="AgentBuilder"/> to control its initial OpenTelemetry registration
+/// </summary>
+public record AgentBuilderOptions
+{
+	/// <summary>
+	/// Provide an additional logger to the internal file logger.
+	/// <para>
+	/// The agent will always log to file if a Path is provided using the <c>ELASTIC_OTEL_LOG_DIRECTORY</c>
+	/// environment variable.</para>
+	/// </summary>
+	public ILogger? Logger { get; init; }
+
+	/// <summary>
+	/// Provides an <see cref="IServiceCollection"/> to register the agent into.
+	/// If null a new local instance will be used.
+	/// </summary>
+	public IServiceCollection? Services { get; init; }
+
+	/// <summary>
+	/// The initial activity sources to listen to.
+	/// <para>>These can always later be amended with <see cref="TracerProviderBuilder.AddSource"/></para>
+	/// </summary>
+	public string[] ActivitySources { get; init; } = [];
+
+	/// <summary>
+	/// Stops <see cref="AgentBuilder"/> to register OLTP exporters, useful for testing scenarios
+	/// </summary>
+	public bool SkipOtlpExporter { get; init; }
+
+	/// <summary>
+    /// Optional name which is used when retrieving OTLP options.
+	/// </summary>
+	public string? OtlpExporterName { get; init; }
+}
+
 /// <summary>
 /// Supports building <see cref="IAgent"/> instances which include Elastic defaults, but can also be customised.
 /// </summary>
 public class AgentBuilder : IOpenTelemetryBuilder
 {
-	private bool _skipOtlpRegistration;
-
-	internal Action<OtlpExporterOptions>? OtlpExporterConfiguration { get; private set; }
-	internal string? OtlpExporterName { get; private set; }
-	internal bool SkipOtlpRegistration => _skipOtlpRegistration;
 	internal AgentCompositeLogger Logger { get; }
 	internal LoggingEventListener EventListener { get; }
 
 	/// <inheritdoc cref="IOpenTelemetryBuilder.Services"/>
 	public IServiceCollection Services { get; }
 
 	/// <summary> TODO </summary>
-	public AgentBuilder(params string[] activitySourceNames) : this(null, null, activitySourceNames) { }
+	public AgentBuilder(params string[] activitySourceNames) : this(new AgentBuilderOptions
+	{
+		ActivitySources = activitySourceNames
+	}) { }
 
 	/// <summary> TODO </summary>
-	public AgentBuilder(ILogger? logger = null, IServiceCollection? services = null, params string[] activitySourceNames)
+	public AgentBuilder(AgentBuilderOptions options)
 	{
-		Logger = new AgentCompositeLogger(logger);
+		Logger = new AgentCompositeLogger(options.Logger);
 
 		// Enables logging of OpenTelemetry-SDK event source events
 		EventListener = new LoggingEventListener(Logger);
 
 		Logger.LogAgentPreamble();
 		Logger.LogAgentBuilderInitialized(Environment.NewLine, new StackTrace(true));
-		Services = services ?? new ServiceCollection();
+		Services = options.Services ?? new ServiceCollection();
 
-		if (services != null)
+		if (options.Services != null)
 			Services.AddHostedService<ElasticOtelDistroService>();
 
 		Services.AddSingleton(this);
@@ -60,7 +95,7 @@ public AgentBuilder(ILogger? logger = null, IServiceCollection? services = null,
 			{
 				tracing.ConfigureResource(r => r.AddDistroAttributes());
 
-				foreach (var source in activitySourceNames)
+				foreach (var source in options.ActivitySources)
 					tracing.LogAndAddSource(source, Logger);
 
 				tracing
@@ -74,7 +109,7 @@ public AgentBuilder(ILogger? logger = null, IServiceCollection? services = null,
 			{
 				metrics.ConfigureResource(r => r.AddDistroAttributes());
 
-				foreach (var source in activitySourceNames)
+				foreach (var source in options.ActivitySources)
 				{
 					Logger.LogMeterAdded(source, metrics.GetType().Name);
 					metrics.AddMeter(source);
@@ -86,24 +121,28 @@ public AgentBuilder(ILogger? logger = null, IServiceCollection? services = null,
 					.AddRuntimeInstrumentation()
 					.AddHttpClientInstrumentation();
 			});
-		Logger.LogAgentBuilderRegisteredServices();
-	}
-
-	/// <summary> TODO </summary>
-	public AgentBuilder SkipOtlpExporter()
-	{
-		_skipOtlpRegistration = true;
-		return this;
-	}
 
+		openTelemetry
+			.WithTracing(tracing =>
+			{
+				if (!options.SkipOtlpExporter)
+					tracing.AddOtlpExporter(options.OtlpExporterName, _ => { });
+				Logger.LogAgentBuilderBuiltTracerProvider();
+			})
+			.WithMetrics(metrics =>
+			{
+				if (!options.SkipOtlpExporter)
+				{
+					metrics.AddOtlpExporter(options.OtlpExporterName, o =>
+					{
+						o.ExportProcessorType = ExportProcessorType.Simple;
+						o.Protocol = OtlpExportProtocol.HttpProtobuf;
+					});
+				}
+				Logger.LogAgentBuilderBuiltMeterProvider();
+			});
 
-	/// <summary>
-	/// TODO
-	/// </summary>
-	public void ConfigureOtlpExporter(Action<OtlpExporterOptions> configure, string? name = null)
-	{
-		OtlpExporterConfiguration = configure ?? throw new ArgumentNullException(nameof(configure));
-		OtlpExporterName = name;
+		Logger.LogAgentBuilderRegisteredServices();
 	}
 }