docs: resource-detector should not be tied to tracing

OpenTelemetry.sln

@@ -333,6 +333,13 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "experimental-apis", "experi
 		docs\diagnostics\experimental-apis\README.md = docs\diagnostics\experimental-apis\README.md
 	EndProjectSection
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "resources", "resources", "{A115CE4C-71A8-4B95-96A5-C1DF46FD94C2}"
+	ProjectSection(SolutionItems) = preProject
+		docs\resources\README.md = docs\resources\README.md
+	EndProjectSection
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "extending-the-sdk", "docs\resources\extending-the-sdk\extending-the-sdk.csproj", "{7BE494FC-4B0D-4340-A62A-9C9F3E7389FE}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -615,6 +622,10 @@ Global
 		{B4856711-6D4C-4246-A686-49458D4C1301}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{B4856711-6D4C-4246-A686-49458D4C1301}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{B4856711-6D4C-4246-A686-49458D4C1301}.Release|Any CPU.Build.0 = Release|Any CPU
+		{7BE494FC-4B0D-4340-A62A-9C9F3E7389FE}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{7BE494FC-4B0D-4340-A62A-9C9F3E7389FE}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{7BE494FC-4B0D-4340-A62A-9C9F3E7389FE}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{7BE494FC-4B0D-4340-A62A-9C9F3E7389FE}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -667,6 +678,8 @@ Global
 		{B4856711-6D4C-4246-A686-49458D4C1301} = {5B7FB835-3FFF-4BC2-99C5-A5B5FAE3C818}
 		{52AF6D7D-9E66-4234-9A2C-5D16C6F22B40} = {7C87CAF9-79D7-4C26-9FFB-F3F1FB6911F1}
 		{17A22B0E-6EC3-4A39-B955-0A486AD06699} = {52AF6D7D-9E66-4234-9A2C-5D16C6F22B40}
+		{A115CE4C-71A8-4B95-96A5-C1DF46FD94C2} = {7C87CAF9-79D7-4C26-9FFB-F3F1FB6911F1}
+		{7BE494FC-4B0D-4340-A62A-9C9F3E7389FE} = {A115CE4C-71A8-4B95-96A5-C1DF46FD94C2}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {55639B5C-0770-4A22-AB56-859604650521}

docs/logs/extending-the-sdk/README.md

@@ -3,6 +3,7 @@
 * [Building your own exporter](#exporter)
 * [Building your own processor](#processor)
 * [Building your own sampler](#sampler)
+* [Building your own resource detector](../../resources/README.md#resource-detector)
 * [References](#references)
 
 ## Exporter

docs/metrics/customizing-the-sdk/README.md

@@ -596,7 +596,7 @@ It is recommended to model attributes that are static throughout the lifetime of
 the process as Resources, instead of adding them as attributes(tags) on each
 measurement.
 
-Follow [this](../../trace/extending-the-sdk/README.md#resource-detector) document
+Follow [this](../../resources/README.md#resource-detector) document
 to learn about writing custom resource detectors.
 
 The snippet below shows configuring the `Resource` associated with the provider.

docs/metrics/extending-the-sdk/README.md

@@ -4,6 +4,7 @@
 * [Building your own reader](#reader)
 * [Building your own exemplar filter](#exemplarfilter)
 * [Building your own exemplar reservoir](#exemplarreservoir)
+* [Building your own resource detector](../../resources/README.md#resource-detector)
 * [References](#references)
 
 ## Exporter

docs/resources/README.md

@@ -0,0 +1,109 @@
+# Resources
+
+## Resource Detector
+
+OpenTelemetry .NET SDK provides a resource detector for detecting resource
+information from the `OTEL_RESOURCE_ATTRIBUTES` and `OTEL_SERVICE_NAME`
+environment variables.
+
+Custom resource detectors can be implemented:
+
+* ResourceDetectors should inherit from
+  `OpenTelemetry.Resources.IResourceDetector`, (which belongs to the
+  [OpenTelemetry](../../src/OpenTelemetry/README.md) package), and implement
+  the `Detect` method.
+
+A demo `ResourceDetector` is shown [here](./extending-the-sdk/MyResourceDetector.cs):
+
+```csharp
+using OpenTelemetry.Resources;
+
+internal class MyResourceDetector : IResourceDetector
+{
+    public Resource Detect()
+    {
+        var attributes = new List<KeyValuePair<string, object>>
+        {
+            new KeyValuePair<string, object>("key", "val"),
+        };
+
+        return new Resource(attributes);
+    }
+}
+```
+
+There are two different ways to add the custom `ResourceDetector` to the
+OTEL signals, via the `Sdk.Create` approach:
+
+```csharp
+using System.Diagnostics;
+using System.Diagnostics.Metrics;
+using Microsoft.Extensions.Logging;
+using OpenTelemetry;
+using OpenTelemetry.Metrics;
+using OpenTelemetry.Resources;
+using OpenTelemetry.Trace;
+
+namespace ExtendingTheSdk;
+
+public class Program
+{
+    private static readonly ActivitySource DemoSource = new("OTel.Demo");
+    private static readonly Meter MeterDemoSource = new("OTel.Demo");
+
+    public static void Main()
+    {
+        using var tracerProvider = Sdk.CreateTracerProviderBuilder()
+            .AddSource("OTel.Demo")
+            .SetResourceBuilder(ResourceBuilder.CreateEmpty().AddDetector(
+                new MyResourceDetector()))
+            .Build();
+
+        using var meterProvider = Sdk.CreateMeterProviderBuilder()
+            .SetResourceBuilder(ResourceBuilder.CreateEmpty().AddDetector(
+                new MyResourceDetector()))
+            .Build();
+
+        using var loggerFactory = LoggerFactory.Create(builder =>
+        {
+            builder.AddOpenTelemetry(options =>
+            {
+                options.SetResourceBuilder(ResourceBuilder
+                    .CreateDefault().AddDetector(
+                        new MyResourceDetector()));
+            });
+        });
+
+        using (var foo = DemoSource.StartActivity("Foo"))
+        {
+            using (var bar = DemoSource.StartActivity("Bar"))
+            {
+                using (var baz = DemoSource.StartActivity("Baz"))
+                {
+                }
+            }
+        }
+
+        var counter = MeterDemoSource.CreateCounter<long>("counter");
+        for (var i = 0; i < 20000; i++)
+            counter.Add(1, new("tag1", "value1"), new("tag2", "value2"));
+
+        var logger = loggerFactory.CreateLogger("OTel.Demo");
+        logger
+            .LogInformation("Hello from {name} {price}.", "tomato", 2.99);
+    }
+}
+```
+
+or via `OpenTelemetry.Extensions.Hosting` method:
+
+```csharp
+    services.AddSingleton<MyResourceDetector>();
+
+    services.AddOpenTelemetry()
+        .ConfigureResource(builder => builder
+            .AddDetector(sp =>
+                sp.GetRequiredService<MyResourceDetector>()))
+        .WithTracing(builder => builder.AddConsoleExporter())
+        .WithMetrics(builder => builder.AddConsoleExporter());
+```

docs/resources/extending-the-sdk/MyResourceDetector.cs

@@ -0,0 +1,17 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+using OpenTelemetry.Resources;
+
+internal class MyResourceDetector : IResourceDetector
+{
+    public Resource Detect()
+    {
+        var attributes = new List<KeyValuePair<string, object>>
+        {
+            new KeyValuePair<string, object>("key", "val"),
+        };
+
+        return new Resource(attributes);
+    }
+}

docs/resources/extending-the-sdk/Program.cs

@@ -0,0 +1,61 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+using System.Diagnostics;
+using System.Diagnostics.Metrics;
+using Microsoft.Extensions.Logging;
+using OpenTelemetry;
+using OpenTelemetry.Metrics;
+using OpenTelemetry.Resources;
+using OpenTelemetry.Trace;
+
+namespace ExtendingTheSdk;
+
+public class Program
+{
+    private static readonly ActivitySource DemoSource = new("OTel.Demo");
+    private static readonly Meter MeterDemoSource = new("OTel.Demo");
+
+    public static void Main()
+    {
+        using var tracerProvider = Sdk.CreateTracerProviderBuilder()
+            .AddSource("OTel.Demo")
+            .SetResourceBuilder(ResourceBuilder.CreateEmpty().AddDetector(
+                new MyResourceDetector()))
+            .Build();
+
+        using var meterProvider = Sdk.CreateMeterProviderBuilder()
+            .SetResourceBuilder(ResourceBuilder.CreateEmpty().AddDetector(
+                new MyResourceDetector()))
+            .Build();
+
+        using var loggerFactory = LoggerFactory.Create(builder =>
+        {
+            builder.AddOpenTelemetry(options =>
+            {
+                options.SetResourceBuilder(ResourceBuilder.CreateDefault().AddDetector(
+                    new MyResourceDetector()));
+            });
+        });
+
+        using (var foo = DemoSource.StartActivity("Foo"))
+        {
+            using (var bar = DemoSource.StartActivity("Bar"))
+            {
+                using (var baz = DemoSource.StartActivity("Baz"))
+                {
+                }
+            }
+        }
+
+        var counter = MeterDemoSource.CreateCounter<long>("counter");
+        for (var i = 0; i < 20000; i++)
+        {
+            counter.Add(1, new KeyValuePair<string, object?>("tag1", "value1"), new KeyValuePair<string, object?>("tag2", "value2"));
+        }
+
+        var logger = loggerFactory.CreateLogger("OTel.Demo");
+        logger
+            .LogInformation("Hello from {Name} {Price}", "tomato", 2.99);
+    }
+}

docs/resources/extending-the-sdk/extending-the-sdk.csproj

@@ -0,0 +1,5 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <ItemGroup>
+    <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry\OpenTelemetry.csproj" />
+  </ItemGroup>
+</Project>

docs/trace/customizing-the-sdk/README.md

@@ -312,7 +312,7 @@ It is recommended to model attributes that are static throughout the lifetime of
 the process as Resources, instead of adding them as attributes(tags) on each
 `Activity`.
 
-Follow [this](../extending-the-sdk/README.md#resource-detector) document
+Follow [this](../../resources/README.md#resource-detector) document
 to learn about writing custom resource detectors.
 
 The snippet below shows configuring the `Resource` associated with the provider.

docs/trace/extending-the-sdk/README.md

@@ -6,7 +6,7 @@ Quick links:
 * [Building your own instrumentation library](#instrumentation-library)
 * [Building your own processor](#processor)
 * [Building your own sampler](#sampler)
-* [Building your own resource detector](#resource-detector)
+* [Building your own resource detector](../../resources/README.md#resource-detector)
 * [Registration extension method guidance for library authors](#registration-extension-method-guidance-for-library-authors)
 * [References](#references)
 
@@ -341,21 +341,6 @@ class MySampler : Sampler
 
 A demo sampler is shown [here](./MySampler.cs).
 
-## Resource Detector
-
-OpenTelemetry .NET SDK provides a resource detector for detecting resource
-information from the `OTEL_RESOURCE_ATTRIBUTES` and `OTEL_SERVICE_NAME`
-environment variables.
-
-Custom resource detectors can be implemented:
-
-* ResourceDetectors should inherit from
-  `OpenTelemetry.Resources.IResourceDetector`, (which belongs to the
-  [OpenTelemetry](../../../src/OpenTelemetry/README.md) package), and implement
-  the `Detect` method.
-
-A demo ResourceDetector is shown [here](./MyResourceDetector.cs).
-
 ## Registration extension method guidance for library authors
 
 > [!NOTE]