Add support for OTEL_SERVICE_NAME environmental variable

src/OpenTelemetry/CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## Unreleased
 
+* `ResourceBuilder.AddEnvironmentVariableDetector` handles `OTEL_SERVICE_NAME`
+   environmental variable. ([#2209](https://github.com/open-telemetry/opentelemetry-dotnet/pull/2209))
+
 * Removes upper constraint for Microsoft.Extensions.Logging
   dependencies. ([#2179](https://github.com/open-telemetry/opentelemetry-dotnet/pull/2179))
 

src/OpenTelemetry/README.md

@@ -5,17 +5,19 @@
 
 * [Installation](#installation)
 * [Introduction](#introduction)
-* [Getting started with Logs](#getting-started-with-logging)
-* [Getting started with Traces](#getting-started-with-tracing)
-* [Tracing Configuration](#tracing-configuration)
-  * [ActivitySource](#activity-source)
+* [Getting started with Logging](#getting-started-with-logging)
+* [Getting started with Tracing](#getting-started-with-tracing)
+* [Tracing configuration](#tracing-configuration)
+  * [Activity Source](#activity-source)
   * [Instrumentation](#instrumentation)
   * [Processor](#processor)
   * [Resource](#resource)
   * [Sampler](#sampler)
 * [Advanced topics](#advanced-topics)
   * [Propagators](#propagators)
 * [Troubleshooting](#troubleshooting)
+  * [Configuration Parameters](#configuration-parameters)
+  * [Remarks](#remarks)
 * [References](#references)
 
 ## Installation
@@ -243,6 +245,16 @@ using var tracerProvider = Sdk.CreateTracerProviderBuilder()
     .Build();
 ```
 
+It is also to configure the resource by using `AddEnvironmentVariableDetector`
+together with following environmental variables:
+
+<!-- markdownlint-disable MD013 -->
+| Environment variable       | Description                                        |
+| -------------------------- | -------------------------------------------------  |
+| `OTEL_RESOURCE_ATTRIBUTES` | Key-value pairs to be used as resource attributes. |
+| `OTEL_SERVICE_NAME`        | Sets the value of the `service.name` resource attribute. If `service.name` is also provided in `OTEL_RESOURCE_ATTRIBUTES`, then `OTEL_SERVICE_NAME` takes precedence. |
+<!-- markdownlint-enable MD013 -->
+
 ### Sampler
 
 [Samplers](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/sdk.md#sampler)

src/OpenTelemetry/Resources/OtelServiceNameEnvVarDetector.cs

@@ -0,0 +1,42 @@
+// <copyright file="OtelServiceNameEnvVarDetector.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;
+using System.Collections.Generic;
+
+namespace OpenTelemetry.Resources
+{
+    internal class OtelServiceNameEnvVarDetector : IResourceDetector
+    {
+        private const string EnvVarKey = "OTEL_SERVICE_NAME";
+
+        public Resource Detect()
+        {
+            var resource = Resource.Empty;
+
+            string envResourceAttributeValue = Environment.GetEnvironmentVariable(EnvVarKey);
+            if (!string.IsNullOrEmpty(envResourceAttributeValue))
+            {
+                resource = new Resource(new Dictionary<string, object>
+                {
+                    [ResourceSemanticConventions.AttributeServiceName] = envResourceAttributeValue,
+                });
+            }
+
+            return resource;
+        }
+    }
+}

src/OpenTelemetry/Resources/ResourceBuilderExtensions.cs

@@ -110,16 +110,16 @@ public static ResourceBuilder AddAttributes(this ResourceBuilder resourceBuilder
         }
 
         /// <summary>
-        /// Adds resource attributes parsed from an environment variable to a
-        /// <see cref="ResourceBuilder"/> following the <a
+        /// Adds resource attributes parsed from OTEL_RESOURCE_ATTRIBUTES, OTEL_SERVICE_NAME environment variables
+        /// to a <see cref="ResourceBuilder"/> following the <a
         /// href="https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/resource/sdk.md#specifying-resource-information-via-an-environment-variable">Resource
         /// SDK</a>.
         /// </summary>
         /// <param name="resourceBuilder"><see cref="ResourceBuilder"/>.</param>
         /// <returns>Returns <see cref="ResourceBuilder"/> for chaining.</returns>
         public static ResourceBuilder AddEnvironmentVariableDetector(this ResourceBuilder resourceBuilder)
         {
-            return resourceBuilder.AddDetector(new OtelEnvResourceDetector());
+            return resourceBuilder.AddDetector(new OtelEnvResourceDetector()).AddDetector(new OtelServiceNameEnvVarDetector());
         }
 
         private static string GetFileVersion()

test/OpenTelemetry.Tests/Resources/OtelServiceNameEnvVarDetectorTests.cs

@@ -0,0 +1,62 @@
+// <copyright file="OtelServiceNameEnvVarDetectorTests.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;
+using System.Collections.Generic;
+using Xunit;
+
+namespace OpenTelemetry.Resources.Tests
+{
+    public class OtelServiceNameEnvVarDetectorTests : IDisposable
+    {
+        private const string OtelEnvVarKey = "OTEL_SERVICE_NAME";
+
+        public OtelServiceNameEnvVarDetectorTests()
+        {
+            Environment.SetEnvironmentVariable(OtelEnvVarKey, null);
+        }
+
+        public void Dispose()
+        {
+            Environment.SetEnvironmentVariable(OtelEnvVarKey, null);
+        }
+
+        [Fact]
+        public void OtelServiceNameEnvVar_Null()
+        {
+            // Act
+            var resource = new OtelServiceNameEnvVarDetector().Detect();
+
+            // Assert
+            Assert.Equal(Resource.Empty, resource);
+        }
+
+        [Fact]
+        public void OtelServiceNameEnvVar_WithValue()
+        {
+            // Arrange
+            var envVarValue = "my-service";
+            Environment.SetEnvironmentVariable(OtelEnvVarKey, envVarValue);
+
+            // Act
+            var resource = new OtelServiceNameEnvVarDetector().Detect();
+
+            // Assert
+            Assert.NotEqual(Resource.Empty, resource);
+            Assert.Contains(new KeyValuePair<string, object>(ResourceSemanticConventions.AttributeServiceName, envVarValue), resource.Attributes);
+        }
+    }
+}

test/OpenTelemetry.Tests/Resources/ResourceTest.cs

@@ -25,11 +25,17 @@ public class ResourceTest : IDisposable
     {
         private const string KeyName = "key";
         private const string ValueName = "value";
-        private const string OtelEnvVarKey = "OTEL_RESOURCE_ATTRIBUTES";
+        private const string ResourceAttributesEnvVarKey = "OTEL_RESOURCE_ATTRIBUTES";
+        private const string ServiceNameEnvVarKey = "OTEL_SERVICE_NAME";
 
         public ResourceTest()
         {
-            Environment.SetEnvironmentVariable(OtelEnvVarKey, null);
+            ClearEnvVars();
+        }
+
+        public void Dispose()
+        {
+            ClearEnvVars();
         }
 
         [Fact]
@@ -421,10 +427,10 @@ public void GetResourceWithDefaultAttributes_ResourceWithAttrs()
         }
 
         [Fact]
-        public void GetResourceWithDefaultAttributes_WithEnvVar()
+        public void GetResourceWithDefaultAttributes_WithResourceEnvVar()
         {
             // Arrange
-            Environment.SetEnvironmentVariable(OtelEnvVarKey, "EVKey1=EVVal1,EVKey2=EVVal2");
+            Environment.SetEnvironmentVariable(ResourceAttributesEnvVarKey, "EVKey1=EVVal1,EVKey2=EVVal2");
             var resource = ResourceBuilder.CreateDefault().AddEnvironmentVariableDetector().AddAttributes(this.CreateAttributes(2)).Build();
 
             // Assert
@@ -436,9 +442,54 @@ public void GetResourceWithDefaultAttributes_WithEnvVar()
             Assert.Contains(new KeyValuePair<string, object>("EVKey2", "EVVal2"), attributes);
         }
 
-        public void Dispose()
+        [Fact]
+        public void GetResource_WithServiceEnvVar()
+        {
+            // Arrange
+            Environment.SetEnvironmentVariable(ServiceNameEnvVarKey, "some-service");
+            var resource = ResourceBuilder.CreateDefault().AddEnvironmentVariableDetector().AddAttributes(this.CreateAttributes(2)).Build();
+
+            // Assert
+            var attributes = resource.Attributes;
+            Assert.Equal(3, attributes.Count());
+            ValidateAttributes(attributes, 0, 1);
+            Assert.Contains(new KeyValuePair<string, object>("service.name", "some-service"), attributes);
+        }
+
+        [Fact]
+        public void GetResource_WithServiceNameSetWithTwoEnvVars()
+        {
+            // Arrange
+            Environment.SetEnvironmentVariable(ResourceAttributesEnvVarKey, "service.name=from-resource-attr");
+            Environment.SetEnvironmentVariable(ServiceNameEnvVarKey, "from-service-name");
+            var resource = ResourceBuilder.CreateDefault().AddEnvironmentVariableDetector().AddAttributes(this.CreateAttributes(2)).Build();
+
+            // Assert
+            var attributes = resource.Attributes;
+            Assert.Equal(3, attributes.Count());
+            ValidateAttributes(attributes, 0, 1);
+            Assert.Contains(new KeyValuePair<string, object>("service.name", "from-service-name"), attributes);
+        }
+
+        [Fact]
+        public void GetResource_WithServiceNameSetWithTwoEnvVarsAndCode()
+        {
+            // Arrange
+            Environment.SetEnvironmentVariable(ResourceAttributesEnvVarKey, "service.name=from-resource-attr");
+            Environment.SetEnvironmentVariable(ServiceNameEnvVarKey, "from-service-name");
+            var resource = ResourceBuilder.CreateDefault().AddEnvironmentVariableDetector().AddService("from-code").AddAttributes(this.CreateAttributes(2)).Build();
+
+            // Assert
+            var attributes = resource.Attributes;
+            Assert.Equal(4, attributes.Count());
+            ValidateAttributes(attributes, 0, 1);
+            Assert.Contains(new KeyValuePair<string, object>("service.name", "from-code"), attributes);
+        }
+
+        private void ClearEnvVars()
         {
-            Environment.SetEnvironmentVariable(OtelEnvVarKey, null);
+            Environment.SetEnvironmentVariable(ResourceAttributesEnvVarKey, null);
+            Environment.SetEnvironmentVariable(ServiceNameEnvVarKey, null);
         }
 
         private static void AddAttributes(Dictionary<string, object> attributes, int attributeCount, int startIndex = 0)