[OpenTelemetry] Add schema URL to resources

OpenTelemetry.Extended.slnx

@@ -156,6 +156,7 @@
     <File Path="src/Shared/Guard.cs" />
     <File Path="src/Shared/PeriodicExportingMetricReaderHelper.cs" />
     <File Path="src/Shared/ResourceSemanticConventions.cs" />
+    <File Path="src/Shared/SchemaUrls.cs" />
     <File Path="src/Shared/SemanticConventions.cs" />
     <File Path="src/Shared/SpanAttributeConstants.cs" />
     <File Path="src/Shared/StatusHelper.cs" />

OpenTelemetry.slnx

@@ -156,6 +156,7 @@
     <File Path="src/Shared/Guard.cs" />
     <File Path="src/Shared/PeriodicExportingMetricReaderHelper.cs" />
     <File Path="src/Shared/ResourceSemanticConventions.cs" />
+    <File Path="src/Shared/SchemaUrls.cs" />
     <File Path="src/Shared/SemanticConventions.cs" />
     <File Path="src/Shared/SpanAttributeConstants.cs" />
     <File Path="src/Shared/StatusHelper.cs" />

src/OpenTelemetry/CHANGELOG.md

@@ -6,6 +6,9 @@ Notes](../../RELEASENOTES.md).
 
 ## Unreleased
 
+* Added Schema URL to internally created `Resource` instances.
+  ([#7726](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7726))
+
 ## 1.18.0
 
 Released 2026-Aug-21

src/OpenTelemetry/OpenTelemetry.csproj

@@ -24,6 +24,7 @@
     <Compile Include="$(RepoRoot)\src\Shared\DoubleExtensions.cs" Link="Includes\DoubleExtensions.cs" />
     <Compile Include="$(RepoRoot)\src\Shared\Options\*.cs" Link="Includes\Options\%(Filename).cs" />
     <Compile Include="$(RepoRoot)\src\Shared\ResourceSemanticConventions.cs" Link="Includes\ResourceSemanticConventions.cs" />
+    <Compile Include="$(RepoRoot)\src\Shared\SchemaUrls.cs" Link="Includes\SchemaUrls.cs" />
     <Compile Include="$(RepoRoot)\src\Shared\Shims\NullableAttributes.cs" Link="Includes\Shims\NullableAttributes.cs" />
     <Compile Include="$(RepoRoot)\src\Shared\StopwatchExtensions.cs" Link="Includes\StopwatchExtensions.cs" />
     <Compile Include="$(RepoRoot)\src\Shared\ThreadSafeRandom.cs" Link="Includes\ThreadSafeRandom.cs" />

src/OpenTelemetry/Resources/OtelServiceNameEnvVarDetector.cs

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 using Microsoft.Extensions.Configuration;
+using OpenTelemetry.Internal;
 
 namespace OpenTelemetry.Resources;
 
@@ -22,10 +23,9 @@ public Resource Detect()
 
         if (this.configuration.TryGetStringValue(EnvVarKey, out var envResourceAttributeValue))
         {
-            resource = new Resource(new Dictionary<string, object>
-            {
-                [ResourceSemanticConventions.AttributeServiceName] = envResourceAttributeValue,
-            });
+            resource = new(
+                [new(ResourceSemanticConventions.AttributeServiceName, envResourceAttributeValue)],
+                SchemaUrls.Get(SemanticConventionsVersion.Current));
         }
 
         return resource;

src/OpenTelemetry/Resources/ResourceBuilder.cs

@@ -149,10 +149,9 @@ private static Resource PrepareDefaultResource()
             // GetCurrentProcess can throw PlatformNotSupportedException
         }
 
-        return new Resource(new Dictionary<string, object>
-        {
-            [ResourceSemanticConventions.AttributeServiceName] = defaultServiceName,
-        });
+        return new Resource(
+            [new(ResourceSemanticConventions.AttributeServiceName, defaultServiceName)],
+            SchemaUrls.Get(SemanticConventionsVersion.Current));
     }
 
     internal sealed class WrapperResourceDetector : IResourceDetector
@@ -177,11 +176,9 @@ public ResolvingResourceDetector(Func<IServiceProvider?, IResourceDetector> reso
             this.resourceDetectorFactory = resourceDetectorFactory;
         }
 
-        public void Resolve(IServiceProvider? serviceProvider)
-        {
+        public void Resolve(IServiceProvider? serviceProvider) =>
             this.resourceDetector = this.resourceDetectorFactory(serviceProvider)
                 ?? throw new InvalidOperationException("ResourceDetector factory did not return a ResourceDetector instance.");
-        }
 
         public Resource Detect()
         {

src/OpenTelemetry/Resources/ResourceBuilderExtensions.cs

@@ -14,12 +14,13 @@ public static class ResourceBuilderExtensions
 {
     private static readonly string InstanceId = Guid.NewGuid().ToString();
 
-    private static Resource TelemetryResource { get; } = new Resource(new Dictionary<string, object>
-    {
-        [ResourceSemanticConventions.AttributeTelemetrySdkName] = "opentelemetry",
-        [ResourceSemanticConventions.AttributeTelemetrySdkLanguage] = "dotnet",
-        [ResourceSemanticConventions.AttributeTelemetrySdkVersion] = Sdk.InformationalVersion,
-    });
+    private static Resource TelemetryResource { get; } = new(
+        [
+            new(ResourceSemanticConventions.AttributeTelemetrySdkName, "opentelemetry"),
+            new(ResourceSemanticConventions.AttributeTelemetrySdkLanguage, "dotnet"),
+            new(ResourceSemanticConventions.AttributeTelemetrySdkVersion, Sdk.InformationalVersion),
+        ],
+        SchemaUrls.Get(SemanticConventionsVersion.Current));
 
     /// <summary>
     /// Adds service information to a <see cref="ResourceBuilder"/>
@@ -45,41 +46,33 @@ public static ResourceBuilder AddService(
         Guard.ThrowIfNull(resourceBuilder);
         Guard.ThrowIfNullOrEmpty(serviceName);
 
-        var resourceAttributes = new Dictionary<string, object>
+        var resourceAttributes = new Dictionary<string, object>(4)
         {
-            { ResourceSemanticConventions.AttributeServiceName, serviceName },
+            [ResourceSemanticConventions.AttributeServiceName] = serviceName,
         };
 
-        if (!string.IsNullOrEmpty(serviceNamespace))
+        if (serviceNamespace is { Length: > 0 })
         {
-#if NET || NETSTANDARD2_1_OR_GREATER
             resourceAttributes.Add(ResourceSemanticConventions.AttributeServiceNamespace, serviceNamespace);
-#else
-            resourceAttributes.Add(ResourceSemanticConventions.AttributeServiceNamespace, serviceNamespace!);
-#endif
         }
 
-        if (!string.IsNullOrEmpty(serviceVersion))
+        if (serviceVersion is { Length: > 0 })
         {
-#if NET || NETSTANDARD2_1_OR_GREATER
             resourceAttributes.Add(ResourceSemanticConventions.AttributeServiceVersion, serviceVersion);
-#else
-            resourceAttributes.Add(ResourceSemanticConventions.AttributeServiceVersion, serviceVersion!);
-#endif
         }
 
         if (serviceInstanceId == null && autoGenerateServiceInstanceId)
         {
             serviceInstanceId = InstanceId;
         }
 
-        if (serviceInstanceId != null)
+        if (serviceInstanceId is { Length: > 0 })
         {
             resourceAttributes.Add(ResourceSemanticConventions.AttributeServiceInstance, serviceInstanceId);
         }
 
 #pragma warning disable CA1062 // Validate arguments of public methods - needed for netstandard2.1
-        return resourceBuilder.AddResource(new Resource(resourceAttributes));
+        return resourceBuilder.AddResource(new Resource(resourceAttributes, SchemaUrls.Get(SemanticConventionsVersion.Current)));
 #pragma warning restore CA1062 // Validate arguments of public methods - needed for netstandard2.1
     }
 

src/OpenTelemetry/SemanticConventionsVersion.cs

@@ -0,0 +1,9 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+namespace OpenTelemetry;
+
+internal static class SemanticConventionsVersion
+{
+    internal static readonly Version Current = new(1, 44, 0);
+}

src/Shared/SchemaUrls.cs

@@ -0,0 +1,10 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+namespace OpenTelemetry.Internal;
+
+internal static class SchemaUrls
+{
+    public static string Get(Version semanticConventionsVersion)
+        => $"https://opentelemetry.io/schemas/{semanticConventionsVersion.ToString(3)}";
+}

test/OpenTelemetry.Tests/Resources/OtelServiceNameEnvVarDetectorTests.cs

@@ -22,9 +22,7 @@ public void Dispose()
 
     [Fact]
     public void OtelServiceNameEnvVar_EnvVarKey()
-    {
-        Assert.Equal("OTEL_SERVICE_NAME", OtelServiceNameEnvVarDetector.EnvVarKey);
-    }
+        => Assert.Equal("OTEL_SERVICE_NAME", OtelServiceNameEnvVarDetector.EnvVarKey);
 
     [Fact]
     public void OtelServiceNameEnvVar_Null()
@@ -36,6 +34,7 @@ public void OtelServiceNameEnvVar_Null()
 
         // Assert
         Assert.Equal(Resource.Empty, resource);
+        Assert.Null(resource.SchemaUrl);
     }
 
     [Fact]
@@ -53,6 +52,7 @@ public void OtelServiceNameEnvVar_WithValue()
         // Assert
         Assert.NotEqual(Resource.Empty, resource);
         Assert.Contains(new KeyValuePair<string, object>(ResourceSemanticConventions.AttributeServiceName, envVarValue), resource.Attributes);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -71,5 +71,6 @@ public void OtelServiceNameEnvVar_UsingIConfiguration()
 
         Assert.NotEqual(Resource.Empty, resource);
         Assert.Contains(new KeyValuePair<string, object>(ResourceSemanticConventions.AttributeServiceName, "my-service"), resource.Attributes);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 }

test/OpenTelemetry.Tests/Resources/ResourceBuilderTests.cs

@@ -13,6 +13,7 @@ public void ServiceResource_ServiceName()
         Assert.Contains(new KeyValuePair<string, object>(ResourceSemanticConventions.AttributeServiceName, "my-service"), resource.Attributes);
         Assert.Single(resource.Attributes, kvp => kvp.Key == ResourceSemanticConventions.AttributeServiceName);
         Assert.True(Guid.TryParse((string)resource.Attributes.Single(kvp => kvp.Key == ResourceSemanticConventions.AttributeServiceInstance).Value, out _));
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -22,6 +23,7 @@ public void ServiceResource_ServiceNameAndInstance()
         Assert.Equal(2, resource.Attributes.Count());
         Assert.Contains(new KeyValuePair<string, object>(ResourceSemanticConventions.AttributeServiceName, "my-service"), resource.Attributes);
         Assert.Contains(new KeyValuePair<string, object>(ResourceSemanticConventions.AttributeServiceInstance, "123"), resource.Attributes);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -32,6 +34,7 @@ public void ServiceResource_ServiceNameAndInstanceAndNamespace()
         Assert.Contains(new KeyValuePair<string, object>(ResourceSemanticConventions.AttributeServiceName, "my-service"), resource.Attributes);
         Assert.Contains(new KeyValuePair<string, object>(ResourceSemanticConventions.AttributeServiceInstance, "123"), resource.Attributes);
         Assert.Contains(new KeyValuePair<string, object>(ResourceSemanticConventions.AttributeServiceNamespace, "my-namespace"), resource.Attributes);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -43,6 +46,7 @@ public void ServiceResource_ServiceNameAndInstanceAndNamespaceAndVersion()
         Assert.Contains(new KeyValuePair<string, object>(ResourceSemanticConventions.AttributeServiceInstance, "123"), resource.Attributes);
         Assert.Contains(new KeyValuePair<string, object>(ResourceSemanticConventions.AttributeServiceNamespace, "my-namespace"), resource.Attributes);
         Assert.Contains(new KeyValuePair<string, object>(ResourceSemanticConventions.AttributeServiceVersion, "1.2.3"), resource.Attributes);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -51,6 +55,7 @@ public void ServiceResource_AutoGenerateServiceInstanceIdOff()
         var resource = ResourceBuilder.CreateEmpty().AddService("my-service", autoGenerateServiceInstanceId: false).Build();
         Assert.Single(resource.Attributes);
         Assert.Contains(new KeyValuePair<string, object>(ResourceSemanticConventions.AttributeServiceName, "my-service"), resource.Attributes);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -81,5 +86,6 @@ public void ClearTest()
             .Build();
         Assert.Single(resource.Attributes);
         Assert.Contains(new KeyValuePair<string, object>(ResourceSemanticConventions.AttributeServiceName, "my-service"), resource.Attributes);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 }

test/OpenTelemetry.Tests/Resources/ResourceTests.cs

@@ -523,13 +523,22 @@ public void ResourceBuilder_Build_PropagatesSchemaUrlFromSingleContributor()
         const string SchemaUrl = "https://opentelemetry.io/schemas/1.36.0";
 
         // A detector contributes a Schema URL; other contributors leave it empty.
-        var resource = ResourceBuilder.CreateDefault()
+        var resource = ResourceBuilder.CreateEmpty()
+            .AddAttributes([new KeyValuePair<string, object>($"{KeyName}0", $"{ValueName}0")])
             .AddAttributes([new KeyValuePair<string, object>(KeyName, ValueName)], SchemaUrl)
             .Build();
 
         Assert.Equal(SchemaUrl, resource.SchemaUrl);
     }
 
+    [Fact]
+    public void ResourceBuilder_Build_DefaultContributorsShareSchemaUrlWithoutConflict()
+    {
+        var resource = ResourceBuilder.CreateDefault().Build();
+
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
+    }
+
     [Fact]
     public void GetResourceWithTelemetrySDKAttributes()
     {
@@ -541,6 +550,7 @@ public void GetResourceWithTelemetrySDKAttributes()
         Assert.Equal(4, attributes.Count());
         ValidateDefaultAttributes(attributes);
         ValidateTelemetrySdkAttributes(attributes);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -554,6 +564,7 @@ public void GetResourceWithDefaultAttributes_EmptyResource()
         Assert.Equal(4, attributes.Count());
         ValidateDefaultAttributes(attributes);
         ValidateTelemetrySdkAttributes(attributes);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -568,6 +579,7 @@ public void GetResourceWithDefaultAttributes_ResourceWithAttrs()
         ValidateAttributes(attributes, 0, 1);
         ValidateDefaultAttributes(attributes);
         ValidateTelemetrySdkAttributes(attributes);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -585,6 +597,7 @@ public void GetResourceWithDefaultAttributes_WithResourceEnvVar()
         Assert.Contains(new KeyValuePair<string, object>("EVKey1", "EVVal1"), attributes);
         Assert.Contains(new KeyValuePair<string, object>("EVKey2", "EVVal2"), attributes);
         ValidateTelemetrySdkAttributes(attributes);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -600,6 +613,7 @@ public void EnvironmentVariableDetectors_DoNotDuplicateAttributes()
         Assert.Contains(new KeyValuePair<string, object>("EVKey1", "EVVal1"), attributes);
         Assert.Contains(new KeyValuePair<string, object>("EVKey2", "EVVal2"), attributes);
         ValidateTelemetrySdkAttributes(attributes);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -615,6 +629,7 @@ public void GetResource_WithServiceEnvVar()
         ValidateAttributes(attributes, 0, 1);
         Assert.Contains(new KeyValuePair<string, object>("service.name", "some-service"), attributes);
         ValidateTelemetrySdkAttributes(attributes);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -631,6 +646,7 @@ public void GetResource_WithServiceNameSetWithTwoEnvVars()
         ValidateAttributes(attributes, 0, 1);
         Assert.Contains(new KeyValuePair<string, object>("service.name", "from-service-name"), attributes);
         ValidateTelemetrySdkAttributes(attributes);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -647,6 +663,7 @@ public void GetResource_WithServiceNameSetWithTwoEnvVarsAndCode()
         ValidateAttributes(attributes, 0, 1);
         Assert.Contains(new KeyValuePair<string, object>("service.name", "from-code"), attributes);
         ValidateTelemetrySdkAttributes(attributes);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -673,6 +690,8 @@ public void ResourceBuilder_AddDetector_Test()
         var resource = builder.Build();
 
         Assert.True(factoryExecuted);
+        Assert.NotNull(resource);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -709,17 +728,23 @@ public void ResourceBuilder_AddDetectorInternal_Test()
             return new NoopResourceDetector();
         });
 
-        builder.Build();
+        var resource = builder.Build();
 
         Assert.True(validTestRun);
+        Assert.NotNull(resource);
+        Assert.StartsWith("https://opentelemetry.io/schemas/", resource.SchemaUrl, StringComparison.Ordinal);
     }
 
     internal static void ValidateTelemetrySdkAttributes(IEnumerable<KeyValuePair<string, object>> attributes)
     {
         Assert.Contains(new KeyValuePair<string, object>("telemetry.sdk.name", "opentelemetry"), attributes);
         Assert.Contains(new KeyValuePair<string, object>("telemetry.sdk.language", "dotnet"), attributes);
+
         var versionAttribute = attributes.Where(pair => pair.Key.Equals("telemetry.sdk.version", StringComparison.Ordinal));
-        Assert.Single(versionAttribute);
+        var version = Assert.Single(versionAttribute);
+        var versionString = Assert.IsType<string>(version.Value);
+
+        Assert.NotEmpty(versionString);
     }
 
     internal static void ValidateDefaultAttributes(IEnumerable<KeyValuePair<string, object>> attributes)