Configure service.instance.id if missing

Configure a default value for the `service.instance.id` resource attribute if not specified by the user.

Author: martincostello

CHANGELOG.md

@@ -17,6 +17,7 @@ This component adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.h
 - Support for file-based configuration of the IL rewrite for
   SqlClient instrumentation setting
 - Add support for `StackExchange.Redis` for applications targeting .NET Framework.
+- Automatically set the `service.instance.id` resource attribute if not provided.
 
 ### Changed
 

src/OpenTelemetry.AutoInstrumentation/Configurations/ResourceConfigurator.cs

@@ -48,6 +48,12 @@ public static ResourceBuilder CreateResourceBuilder(ResourceSettings resourceSet
             resourceBuilder.AddAttributes([new(Constants.ResourceAttributes.AttributeServiceName, ServiceNameConfigurator.GetFallbackServiceName())]);
         }
 
+        if (resource.Attributes.All(kvp => kvp.Key != Constants.ResourceAttributes.AttributeServiceInstanceId))
+        {
+            // service.instance.id was not configured yet use the fallback.
+            resourceBuilder.AddAttributes([new(Constants.ResourceAttributes.AttributeServiceInstanceId, Guid.NewGuid().ToString())]);
+        }
+
         var pluginManager = Instrumentation.PluginManager;
         if (pluginManager != null)
         {

src/OpenTelemetry.AutoInstrumentation/Constants.cs

@@ -27,6 +27,7 @@ public static class HttpSpanAttributes
     public static class ResourceAttributes
     {
         public const string AttributeServiceName = "service.name";
+        public const string AttributeServiceInstanceId = "service.instance.id";
     }
 
     public static class ConfigurationValues

test/IntegrationTests/AspNetTests.cs

@@ -8,7 +8,7 @@
 
 namespace IntegrationTests;
 
-public class AspNetTests
+public class AspNetTests(ITestOutputHelper output)
 {
     private const string ServiceName = "TestApplication.AspNet.NetFramework";
 
@@ -22,11 +22,6 @@ public class AspNetTests
         }
     };
 
-    public AspNetTests(ITestOutputHelper output)
-    {
-        Output = output;
-    }
-
     public enum Gac
     {
         /// <summary>
@@ -53,7 +48,7 @@ public enum AppPoolMode
         Integrated
     }
 
-    private ITestOutputHelper Output { get; }
+    private ITestOutputHelper Output { get; } = output;
 
     [Theory]
     [Trait("Category", "EndToEnd")]
@@ -179,8 +174,9 @@ public async Task TracesResource()
         // on the firewall.
         using var collector = new MockSpansCollector(Output, host: "*");
         using var fwPort = FirewallHelper.OpenWinPort(collector.Port, Output);
-        collector.ResourceExpector.Expect("service.name", ServiceName); // this is set via env var in Dockerfile and Wep.config, but env var has precedence
-        collector.ResourceExpector.Expect("deployment.environment.name", "test"); // this is set via Wep.config
+        collector.ResourceExpector.Expect("service.name", ServiceName); // this is set via env var in Dockerfile and Web.config, but env var has precedence
+        collector.ResourceExpector.Expect("deployment.environment.name", "test"); // this is set via Web.config
+        collector.ResourceExpector.Exist("service.instance.id"); // automatically generated
 
         var collectorUrl = $"http://{DockerNetworkHelper.IntegrationTestsGateway}:{collector.Port}";
 

test/IntegrationTests/Helpers/OtlpResourceExpectorExtensions.cs

@@ -40,5 +40,6 @@ public static void ExpectStandardResources(this OtlpResourceExpector resourceExp
         resourceExpector.Exist("os.description");
         resourceExpector.Exist("os.name");
         resourceExpector.Exist("os.version");
+        resourceExpector.Exist("service.instance.id");
     }
 }

test/OpenTelemetry.AutoInstrumentation.Tests/Configurations/ServiceNameConfiguratorTests.cs

@@ -9,8 +9,10 @@ namespace OpenTelemetry.AutoInstrumentation.Tests.Configurations;
 [Collection("Non-Parallel Collection")]
 public class ServiceNameConfiguratorTests
 {
+    private const string ServiceInstanceId = "service.instance.id";
     private const string ServiceName = "service.name";
     private const string OtelServiceVariable = "OTEL_SERVICE_NAME";
+    private const string OtelResourceAttributeVariable = "OTEL_RESOURCE_ATTRIBUTES";
 
     [Fact]
     public void GetFallbackServiceName()
@@ -22,24 +24,30 @@ public void GetFallbackServiceName()
         Assert.Matches("testhost|ReSharperTestRunner", serviceName);
     }
 
-    [Fact]
-    public void ServiceName_Retained_EnvVarSet()
+    [Theory]
+    [InlineData(ServiceName, OtelServiceVariable, "TestApplication", "TestApplication")]
+    [InlineData(ServiceName, OtelResourceAttributeVariable, $"{ServiceName}=TestApplication", "TestApplication")]
+    [InlineData(ServiceInstanceId, OtelResourceAttributeVariable, $"{ServiceInstanceId}=c8de43ab-0121-4a4a-84ff-2177e1613304", "c8de43ab-0121-4a4a-84ff-2177e1613304")]
+    public void Environment_Variable_Not_Overwritten(
+        string attributeName,
+        string variableName,
+        string variableValue,
+        string expectedValue)
     {
-        const string setServiceName = "TestApplication";
         try
         {
-            Environment.SetEnvironmentVariable(OtelServiceVariable, setServiceName);
+            Environment.SetEnvironmentVariable(variableName, variableValue);
 
             var resourceBuilder = ResourceConfigurator.CreateResourceBuilder(new ResourceSettings());
             var resource = resourceBuilder.Build();
 
-            var serviceName = resource.Attributes.FirstOrDefault(a => a.Key == ServiceName).Value as string;
+            var actualVaue = resource.Attributes.FirstOrDefault(a => a.Key == attributeName).Value as string;
 
-            Assert.Equal(setServiceName, serviceName);
+            Assert.Equal(expectedValue, actualVaue);
         }
         finally
         {
-            Environment.SetEnvironmentVariable(OtelServiceVariable, null);
+            Environment.SetEnvironmentVariable(variableName, null);
         }
     }
 }