exports service.name to StackDriver if the value is present in an ins…

…tance of OpenTelemetry.Resources.Resource (#1652)

When many services collaborate, information about a service's name can help understand which service creates which trace. Google Trace Explorer allows the display of a service name next to trace information.

src/OpenTelemetry.Exporter.Stackdriver/CHANGELOG.md

@@ -4,6 +4,9 @@
 
 * Update OpenTelemetry SDK version to `1.8.0`.
   ([#1635](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/1635))
+* When many services collaborate, information about a service's name can help understand which service creates which trace.
+  Google Trace Explorer allows the display of a service name next to trace information.
+  Please use `services.ConfigureResource(resource => resource.AddService("my-service", "1.0.0"))` to add service name and version.
 
 ## 1.0.0-beta.5
 

src/OpenTelemetry.Exporter.Stackdriver/Implementation/ResourceExtensions.cs

@@ -0,0 +1,38 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+using System.Collections.Generic;
+using Google.Cloud.Trace.V2;
+using OpenTelemetry.Resources;
+
+namespace OpenTelemetry.Exporter.Stackdriver.Implementation;
+
+internal static class ResourceExtensions
+{
+    private static readonly HashSet<string> ExportableResourceNames =
+    [
+        ResourceSemanticConventions.AttributeServiceName,
+        ResourceSemanticConventions.AttributeServiceVersion
+    ];
+
+    /// <summary>
+    ///     Adds resource attributes to the span.
+    /// </summary>
+    /// <param name="span">Google Cloud Trace Span to be annotated.</param>
+    /// <param name="resource">
+    ///     The Resource contains attributes such as "service.name" that provide metadata about the service being traced.
+    ///     These attributes are used to annotate the Google Cloud Trace Span, enhancing the trace data available in the Google
+    ///     Trace Explorer UI.
+    /// </param>
+    public static void AnnotateWith(this Span span, Resource resource)
+    {
+        span.Attributes ??= new Span.Types.Attributes();
+        foreach (var attr in resource.Attributes)
+        {
+            if (ExportableResourceNames.Contains(attr.Key))
+            {
+                span.Attributes.AttributeMap.Add(attr.Key, attr.Value.ToAttributeValue());
+            }
+        }
+    }
+}

src/OpenTelemetry.Exporter.Stackdriver/Implementation/ResourceSemanticConventions.cs

@@ -0,0 +1,10 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+namespace OpenTelemetry.Exporter.Stackdriver.Implementation;
+
+internal class ResourceSemanticConventions
+{
+    public const string AttributeServiceName = "service.name";
+    public const string AttributeServiceVersion = "service.version";
+}

src/OpenTelemetry.Exporter.Stackdriver/StackdriverTraceExporter.cs

@@ -10,6 +10,7 @@
 using Google.Cloud.Trace.V2;
 using Grpc.Core;
 using OpenTelemetry.Exporter.Stackdriver.Implementation;
+using OpenTelemetry.Resources;
 
 namespace OpenTelemetry.Exporter.Stackdriver;
 
@@ -93,12 +94,19 @@ public override ExportResult Export(in Batch<Activity> batch)
             ProjectName = this.googleCloudProjectId,
         };
 
+        Resource? resource = this.ParentProvider?.GetResource();
         foreach (var activity in batch)
         {
             // It should never happen that the time has no correct kind, only if OpenTelemetry is used incorrectly.
             if (activity.StartTimeUtc.Kind == DateTimeKind.Utc)
             {
-                batchSpansRequest.Spans.Add(activity.ToSpan(this.googleCloudProjectId.ProjectId));
+                Span span = activity.ToSpan(this.googleCloudProjectId.ProjectId);
+                if (resource != null)
+                {
+                    span.AnnotateWith(resource);
+                }
+
+                batchSpansRequest.Spans.Add(span);
             }
         }
 

test/OpenTelemetry.Exporter.Stackdriver.Tests/ResourceExtensionsTests.cs

@@ -0,0 +1,46 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+using System.Collections.Generic;
+using Google.Cloud.Trace.V2;
+using OpenTelemetry.Exporter.Stackdriver.Implementation;
+using OpenTelemetry.Resources;
+using Xunit;
+
+namespace OpenTelemetry.Exporter.Stackdriver.Tests;
+
+public class ResourceExtensionsTests
+{
+    [Fact]
+    public void Enriches_Span_Attributes_With_Service_Name()
+    {
+        const string serviceName = "some service name";
+        const string serviceVersion = "2.3.4";
+        var resource = new Resource(new Dictionary<string, object>
+        {
+            ["key1"] = "value1",
+            ["key2"] = "value2",
+            [ResourceSemanticConventions.AttributeServiceName] = serviceName,
+            [ResourceSemanticConventions.AttributeServiceVersion] = serviceVersion,
+        });
+
+        var span = new Span();
+        span.AnnotateWith(resource);
+        Assert.Contains(span.Attributes.AttributeMap, kvp =>
+            kvp.Key == ResourceSemanticConventions.AttributeServiceName &&
+            kvp.Value.StringValue.Value == serviceName);
+
+        Assert.Contains(span.Attributes.AttributeMap, kvp =>
+            kvp.Key == ResourceSemanticConventions.AttributeServiceVersion &&
+            kvp.Value.StringValue.Value == serviceVersion);
+    }
+
+    [Fact]
+    public void Otel_Resource_Has_No_Service_Name()
+    {
+        var resource = new Resource(new Dictionary<string, object> { ["key1"] = "value1", ["key2"] = "value2" });
+
+        var span = new Span();
+        span.AnnotateWith(resource);
+    }
+}