Publicize required methods to allow for custom implementations of resource detectors.

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

@@ -0,0 +1,31 @@
+// <copyright file="MyResourceDetector.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.Collections.Generic;
+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/trace/extending-the-sdk/Program.cs

@@ -16,6 +16,7 @@
 
 using System.Diagnostics;
 using OpenTelemetry;
+using OpenTelemetry.Resources;
 using OpenTelemetry.Trace;
 
 public class Program
@@ -27,6 +28,7 @@ public static void Main()
         using var tracerProvider = Sdk.CreateTracerProviderBuilder()
             .SetSampler(new MySampler())
             .AddSource("OTel.Demo")
+            .SetResourceBuilder(ResourceBuilder.CreateEmpty().AddDetector(new MyResourceDetector()))
             .AddProcessor(new MyProcessor("ProcessorA"))
             .AddProcessor(new MyProcessor("ProcessorB"))
             .AddProcessor(new SimpleActivityExportProcessor(new MyExporter("ExporterX")))

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

@@ -4,6 +4,7 @@
 * [Building your own instrumentation library](#instrumentation-library)
 * [Building your own processor](#processor)
 * [Building your own sampler](#sampler)
+* [Building your own resource detector](#resource-detector)
 * [References](#references)
 
 ## Exporter
@@ -293,6 +294,21 @@ 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).
+
 ## References
 
 * [Exporter

src/OpenTelemetry/.publicApi/net461/PublicAPI.Unshipped.txt

@@ -114,6 +114,8 @@ OpenTelemetry.ReadOnlyTagCollection.GetEnumerator() -> OpenTelemetry.ReadOnlyTag
 OpenTelemetry.ReadOnlyTagCollection.ReadOnlyTagCollection() -> void
 OpenTelemetry.Resources.IResourceDetector
 OpenTelemetry.Resources.IResourceDetector.Detect() -> OpenTelemetry.Resources.Resource
+OpenTelemetry.Resources.Resource.Resource(System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, object>> attributes) -> void
+OpenTelemetry.Resources.ResourceBuilder.AddDetector(OpenTelemetry.Resources.IResourceDetector resourceDetector) -> OpenTelemetry.Resources.ResourceBuilder
 OpenTelemetry.Trace.BatchExportActivityProcessorOptions
 OpenTelemetry.Trace.BatchExportActivityProcessorOptions.BatchExportActivityProcessorOptions() -> void
 override OpenTelemetry.BaseExportProcessor<T>.OnForceFlush(int timeoutMilliseconds) -> bool

src/OpenTelemetry/.publicApi/netstandard2.0/PublicAPI.Unshipped.txt

@@ -114,6 +114,8 @@ OpenTelemetry.ReadOnlyTagCollection.GetEnumerator() -> OpenTelemetry.ReadOnlyTag
 OpenTelemetry.ReadOnlyTagCollection.ReadOnlyTagCollection() -> void
 OpenTelemetry.Resources.IResourceDetector
 OpenTelemetry.Resources.IResourceDetector.Detect() -> OpenTelemetry.Resources.Resource
+OpenTelemetry.Resources.Resource.Resource(System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, object>> attributes) -> void
+OpenTelemetry.Resources.ResourceBuilder.AddDetector(OpenTelemetry.Resources.IResourceDetector resourceDetector) -> OpenTelemetry.Resources.ResourceBuilder
 OpenTelemetry.Trace.BatchExportActivityProcessorOptions
 OpenTelemetry.Trace.BatchExportActivityProcessorOptions.BatchExportActivityProcessorOptions() -> void
 override OpenTelemetry.BaseExportProcessor<T>.OnForceFlush(int timeoutMilliseconds) -> bool

src/OpenTelemetry/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+* Publicize required methods to allow for custom implementations of resource
+  detectors.
+  ([2949](https://github.com/open-telemetry/opentelemetry-dotnet/pull/2949/))
+
 * Make `IResourceDetector` public to allow custom implementations of resource
   detectors.
   ([2897](https://github.com/open-telemetry/opentelemetry-dotnet/pull/2897))

src/OpenTelemetry/Resources/Resource.cs

@@ -35,7 +35,7 @@ public class Resource
         /// Initializes a new instance of the <see cref="Resource"/> class.
         /// </summary>
         /// <param name="attributes">An <see cref="IEnumerable{T}"/> of attributes that describe the resource.</param>
-        internal Resource(IEnumerable<KeyValuePair<string, object>> attributes)
+        public Resource(IEnumerable<KeyValuePair<string, object>> attributes)
         {
             if (attributes == null)
             {

src/OpenTelemetry/Resources/ResourceBuilder.cs

@@ -86,9 +86,7 @@ public Resource Build()
             return finalResource;
         }
 
-        // Internal until spec is finalized.
-        // https://github.com/open-telemetry/oteps/blob/master/text/0111-auto-resource-detection.md
-        internal ResourceBuilder AddDetector(IResourceDetector resourceDetector)
+        public ResourceBuilder AddDetector(IResourceDetector resourceDetector)
         {
             Guard.ThrowIfNull(resourceDetector);