Default Resource should have service.name attribute

src/OpenTelemetry/CHANGELOG.md

@@ -44,6 +44,10 @@ Released 2021-Jan-29
   [#1501](https://github.com/open-telemetry/opentelemetry-dotnet/pull/1655)
   for details on Metric release plans.
 * Fix Resource attribute telemetry.sdk.version to have correct file version.
+* Default `Resource` has been updated. No longer linked to Telemetry SDK,
+  but that enabled through .AddTelemetrySDK() extensions. Instead provides
+  default service.name attribute composed of local service and process name.
+  [#1744](https://github.com/open-telemetry/opentelemetry-dotnet/pull/1744)
 
 ## 1.0.0-rc1.1
 

src/OpenTelemetry/Resources/ResourceBuilder.cs

@@ -30,15 +30,22 @@ private ResourceBuilder()
         {
         }
 
+        private static Resource DefaultResource { get; } = new Resource(new Dictionary<string, object>
+        {
+            [ResourceSemanticConventions.AttributeServiceName] = "unknown_service:"
+                + (string.IsNullOrWhiteSpace(System.Diagnostics.Process.GetCurrentProcess().ProcessName)
+                ? System.Diagnostics.Process.GetCurrentProcess().ProcessName : string.Empty),
+        });
+
         /// <summary>
-        /// Creates a <see cref="ResourceBuilder"/> instance with SDK defaults
-        /// added. See <a
-        /// href="https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/resource/semantic_conventions/">resource
+        /// Creates a <see cref="ResourceBuilder"/> instance with Default
+        /// service.name added. See <a
+        /// href="https://github.com/open-telemetry/opentelemetry-specification/tree/master/specification/resource/semantic_conventions#service/">resource
         /// semantic conventions</a> for details.
         /// </summary>
         /// <returns>Created <see cref="ResourceBuilder"/>.</returns>
         public static ResourceBuilder CreateDefault()
-            => new ResourceBuilder().AddTelemetrySdk(); // TODO: Seek spec clarify on whether or not OtelEnvResourceDetector should be added by default.
+            => new ResourceBuilder().AddResource(DefaultResource);
 
         /// <summary>
         /// Creates an empty <see cref="ResourceBuilder"/> instance.

src/OpenTelemetry/Resources/ResourceBuilderExtensions.cs

@@ -90,7 +90,7 @@ public static ResourceBuilder AddService(
         /// <summary>
         /// Adds service information to a <see cref="ResourceBuilder"/>
         /// following <a
-        /// href="https://github.com/open-telemetry/opentelemetry-specification/tree/main/specification/resource/semantic_conventions#telemetry-sdk">semantic
+        /// href="https://github.com/open-telemetry/opentelemetry-specification/tree/master/specification/resource/semantic_conventions#telemetry-sdk">semantic
         /// conventions</a>.
         /// </summary>
         /// <param name="resourceBuilder"><see cref="ResourceBuilder"/>.</param>

test/OpenTelemetry.Tests/Resources/ResourceTest.cs

@@ -330,6 +330,18 @@ public void MergeResource_UpdatingResourceOverridesCurrentResource()
             Assert.Contains(new KeyValuePair<string, object>("value", "updatedValue"), newResource.Attributes);
         }
 
+        [Fact]
+        public void GetResourceWithTelemetrySDKAttributes()
+        {
+            // Arrange
+            var resource = ResourceBuilder.CreateDefault().AddTelemetrySdk().AddEnvironmentVariableDetector().Build();
+
+            // Assert
+            var attributes = resource.Attributes;
+            Assert.Equal(4, attributes.Count());
+            ValidateTelemetrySdkAttributes(attributes);
+        }
+
         [Fact]
         public void GetResourceWithDefaultAttributes_EmptyResource()
         {
@@ -338,8 +350,8 @@ public void GetResourceWithDefaultAttributes_EmptyResource()
 
             // Assert
             var attributes = resource.Attributes;
-            Assert.Equal(3, attributes.Count());
-            ValidateTelemetrySdkAttributes(attributes);
+            Assert.Single(attributes);
+            ValidateDefaultAttributes(attributes);
         }
 
         [Fact]
@@ -350,9 +362,9 @@ public void GetResourceWithDefaultAttributes_ResourceWithAttrs()
 
             // Assert
             var attributes = resource.Attributes;
-            Assert.Equal(5, attributes.Count());
+            Assert.Equal(3, attributes.Count());
             ValidateAttributes(attributes, 0, 1);
-            ValidateTelemetrySdkAttributes(attributes);
+            ValidateDefaultAttributes(attributes);
         }
 
         [Fact]
@@ -364,9 +376,9 @@ public void GetResourceWithDefaultAttributes_WithEnvVar()
 
             // Assert
             var attributes = resource.Attributes;
-            Assert.Equal(7, attributes.Count());
+            Assert.Equal(5, attributes.Count());
             ValidateAttributes(attributes, 0, 1);
-            ValidateTelemetrySdkAttributes(attributes);
+            ValidateDefaultAttributes(attributes);
             Assert.Contains(new KeyValuePair<string, object>("EVKey1", "EVVal1"), attributes);
             Assert.Contains(new KeyValuePair<string, object>("EVKey2", "EVVal2"), attributes);
         }
@@ -412,6 +424,13 @@ private static void ValidateTelemetrySdkAttributes(IEnumerable<KeyValuePair<stri
             Assert.Single(versionAttribute);
         }
 
+        private static void ValidateDefaultAttributes(IEnumerable<KeyValuePair<string, object>> attributes)
+        {
+            var serviceName = attributes.Where(pair => pair.Key.Equals("service.name"));
+            Assert.Single(serviceName);
+            Assert.Contains("unknown_service:", serviceName.FirstOrDefault().Value as string);
+        }
+
         private Dictionary<string, object> CreateAttributes(int attributeCount, int startIndex = 0)
         {
             var attributes = new Dictionary<string, object>();

test/OpenTelemetry.Tests/Trace/TracerProviderSdkTest.cs

@@ -375,6 +375,22 @@ public void TracerProviderSdkBuildsWithDefaultResource()
             var resource = tracerProvider.GetResource();
             var attributes = resource.Attributes;
 
+            Assert.NotNull(resource);
+            Assert.NotEqual(Resource.Empty, resource);
+            Assert.Single(resource.Attributes);
+            Assert.Equal(resource.Attributes.FirstOrDefault().Key, ResourceSemanticConventions.AttributeServiceName);
+            Assert.Contains("unknown_service:", (string)resource.Attributes.FirstOrDefault().Value);
+
+        }
+
+        [Fact]
+        public void TracerProviderSdkBuildsWithSDKResource()
+        {
+            var tracerProvider = Sdk.CreateTracerProviderBuilder().SetResourceBuilder(
+                ResourceBuilder.CreateDefault().AddTelemetrySdk()).Build();
+            var resource = tracerProvider.GetResource();
+            var attributes = resource.Attributes;
+
             Assert.NotNull(resource);
             Assert.NotEqual(Resource.Empty, resource);
             Assert.Contains(new KeyValuePair<string, object>("telemetry.sdk.name", "opentelemetry"), attributes);