feat(context): prototype context-scoped attributes (#8532)

api/incubator/src/main/java/io/opentelemetry/api/incubator/common/ContextAttributes.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.api.incubator.common;
+
+import static java.util.Objects.requireNonNull;
+
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.context.Context;
+import io.opentelemetry.context.ContextKey;
+
+/**
+ * Utility for associating {@link Attributes} with a {@link Context} for automatic propagation to
+ * telemetry signals produced within that context.
+ */
+public final class ContextAttributes {
+
+  private static final ContextKey<Attributes> CONTEXT_ATTRIBUTES_KEY =
+      ContextKey.named("opentelemetry-context-attributes");
+
+  private ContextAttributes() {}
+
+  /**
+   * Returns a new {@link Context} containing the merged attributes from the given {@code context}
+   * and {@code attributes}. If the same attribute key is present in both, the value from {@code
+   * attributes} takes precedence.
+   */
+  public static Context add(Context context, Attributes attributes) {
+    requireNonNull(context, "context");
+    if (attributes == null || attributes.isEmpty()) {
+      return context;
+    }
+    Attributes existing = context.get(CONTEXT_ATTRIBUTES_KEY);
+    if (existing == null) {
+      return context.with(CONTEXT_ATTRIBUTES_KEY, attributes);
+    }
+    Attributes merged = existing.toBuilder().putAll(attributes).build();
+    return context.with(CONTEXT_ATTRIBUTES_KEY, merged);
+  }
+
+  /**
+   * Returns the {@link Attributes} associated with the given {@code context}, or {@link
+   * Attributes#empty()} if none are present.
+   *
+   * <p>This method is intended primarily for telemetry pipeline components such as SDKs, samplers,
+   * processors, and exporters. Application code should treat context-scoped attributes as
+   * write-only via {@link #add(Context, Attributes)}.
+   */
+  public static Attributes get(Context context) {
+    if (context == null) {
+      return Attributes.empty();
+    }
+    Attributes attributes = context.get(CONTEXT_ATTRIBUTES_KEY);
+    return attributes != null ? attributes : Attributes.empty();
+  }
+}

api/incubator/src/test/java/io/opentelemetry/api/incubator/common/ContextAttributesTest.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.api.incubator.common;
+
+import static io.opentelemetry.api.common.AttributeKey.longKey;
+import static io.opentelemetry.api.common.AttributeKey.stringKey;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.context.Context;
+import io.opentelemetry.context.Scope;
+import org.junit.jupiter.api.Test;
+
+class ContextAttributesTest {
+
+  @Test
+  void emptyContext_returnsEmptyAttributes() {
+    assertThat(ContextAttributes.get(Context.root())).isEqualTo(Attributes.empty());
+    assertThat(ContextAttributes.get(null)).isEqualTo(Attributes.empty());
+  }
+
+  @Test
+  void addNullOrEmptyAttributes_returnsSameContext() {
+    Context root = Context.root();
+    assertThat(ContextAttributes.add(root, null)).isSameAs(root);
+    assertThat(ContextAttributes.add(root, Attributes.empty())).isSameAs(root);
+    assertThatThrownBy(() -> ContextAttributes.add(null, Attributes.of(stringKey("k"), "v")))
+        .isInstanceOf(NullPointerException.class);
+  }
+
+  @Test
+  void addAndGet_singleLayer() {
+    Attributes attrs = Attributes.of(stringKey("user.id"), "u123", longKey("retry"), 1L);
+    Context ctx = ContextAttributes.add(Context.root(), attrs);
+
+    assertThat(ContextAttributes.get(ctx)).isEqualTo(attrs);
+    assertThat(ContextAttributes.get(Context.root())).isEqualTo(Attributes.empty());
+  }
+
+  @Test
+  void addAndGet_nestedContextsMergeAndOverride() {
+    Context outer =
+        ContextAttributes.add(
+            Context.root(), Attributes.of(stringKey("k1"), "v1", stringKey("k2"), "v2"));
+    Context inner =
+        ContextAttributes.add(
+            outer, Attributes.of(stringKey("k2"), "v2-override", stringKey("k3"), "v3"));
+
+    assertThat(ContextAttributes.get(outer))
+        .isEqualTo(Attributes.of(stringKey("k1"), "v1", stringKey("k2"), "v2"));
+    assertThat(ContextAttributes.get(inner))
+        .isEqualTo(
+            Attributes.of(
+                stringKey("k1"), "v1", stringKey("k2"), "v2-override", stringKey("k3"), "v3"));
+  }
+
+  @Test
+  void scopeAttachment_restoresOuterContextAttributesOnClose() {
+    Context outer = ContextAttributes.add(Context.root(), Attributes.of(stringKey("env"), "prod"));
+    try (Scope ignoredOuter = outer.makeCurrent()) {
+      assertThat(ContextAttributes.get(Context.current()))
+          .isEqualTo(Attributes.of(stringKey("env"), "prod"));
+
+      Context inner =
+          ContextAttributes.add(
+              Context.current(),
+              Attributes.of(stringKey("env"), "staging", stringKey("req"), "r1"));
+      try (Scope ignoredInner = inner.makeCurrent()) {
+        assertThat(ContextAttributes.get(Context.current()))
+            .isEqualTo(Attributes.of(stringKey("env"), "staging", stringKey("req"), "r1"));
+      }
+
+      assertThat(ContextAttributes.get(Context.current()))
+          .isEqualTo(Attributes.of(stringKey("env"), "prod"));
+    }
+    assertThat(ContextAttributes.get(Context.current())).isEqualTo(Attributes.empty());
+  }
+}

sdk-extensions/declarative-config/src/main/java/io/opentelemetry/sdk/autoconfigure/declarativeconfig/LoggerProviderFactory.java

@@ -91,6 +91,12 @@ public SdkLoggerProviderBuilder create(
       SdkLoggerProviderUtil.setLoggerConfigurator(builder, configuratorBuilder.build());
     }
 
+    Boolean contextScopedAttributes =
+        LoggerProviderModelAccessor.getContextScopedAttributes(loggerProviderModel);
+    if (contextScopedAttributes != null) {
+      SdkLoggerProviderUtil.setContextScopedAttributesEnabled(builder, contextScopedAttributes);
+    }
+
     return builder;
   }
 

sdk-extensions/declarative-config/src/main/java/io/opentelemetry/sdk/autoconfigure/declarativeconfig/MeterProviderFactory.java

@@ -103,6 +103,11 @@ public SdkMeterProviderBuilder create(
           ExemplarFilterFactory.getInstance().create(exemplarFilterModel, context));
     }
 
+    Boolean contextScopedAttributes = MeterProviderModelAccessor.getContextScopedAttributes(model);
+    if (contextScopedAttributes != null) {
+      SdkMeterProviderUtil.setContextScopedAttributesEnabled(builder, contextScopedAttributes);
+    }
+
     return builder;
   }
 

sdk-extensions/declarative-config/src/main/java/io/opentelemetry/sdk/autoconfigure/declarativeconfig/TracerProviderFactory.java

@@ -99,6 +99,12 @@ public SdkTracerProviderBuilder create(
       SdkTracerProviderUtil.setTracerConfigurator(builder, configuratorBuilder.build());
     }
 
+    Boolean contextScopedAttributes =
+        TracerProviderModelAccessor.getContextScopedAttributes(tracerProviderModel);
+    if (contextScopedAttributes != null) {
+      SdkTracerProviderUtil.setContextScopedAttributesEnabled(builder, contextScopedAttributes);
+    }
+
     return builder;
   }
 

sdk-extensions/declarative-config/src/main/java/io/opentelemetry/sdk/autoconfigure/declarativeconfig/model/internal/LoggerProviderModelAccessor.java

@@ -24,12 +24,14 @@ public final class LoggerProviderModelAccessor {
   private LoggerProviderModelAccessor() {}
 
   static final String LOGGER_CONFIGURATOR = "logger_configurator/development";
+  static final String CONTEXT_SCOPED_ATTRIBUTES = "context_scoped_attributes/development";
 
   public static final Map<String, Class<?>> EXPERIMENTAL_PROPERTIES;
 
   static {
     EXPERIMENTAL_PROPERTIES = new HashMap<>();
     EXPERIMENTAL_PROPERTIES.put(LOGGER_CONFIGURATOR, ExperimentalLoggerConfiguratorModel.class);
+    EXPERIMENTAL_PROPERTIES.put(CONTEXT_SCOPED_ATTRIBUTES, Boolean.class);
   }
 
   @Nullable
@@ -47,4 +49,17 @@ public static LoggerProviderModel setLoggerConfigurator(
     model.setExtensionProperty(LOGGER_CONFIGURATOR, value);
     return model;
   }
+
+  @Nullable
+  public static Boolean getContextScopedAttributes(LoggerProviderModel model) {
+    return ExtensionPropertyUtil.get(
+        CONTEXT_SCOPED_ATTRIBUTES, model.getExtensionProperties(), Boolean.class);
+  }
+
+  public static LoggerProviderModel setContextScopedAttributes(
+      LoggerProviderModel model, Boolean value) {
+    requireNonNull(value, "value");
+    model.setExtensionProperty(CONTEXT_SCOPED_ATTRIBUTES, value);
+    return model;
+  }
 }

sdk-extensions/declarative-config/src/main/java/io/opentelemetry/sdk/autoconfigure/declarativeconfig/model/internal/MeterProviderModelAccessor.java

@@ -25,13 +25,15 @@ private MeterProviderModelAccessor() {}
 
   static final String METER_CONFIGURATOR = "meter_configurator/development";
   static final String VIEW_MATCHING_MODE = "view_matching_mode/development";
+  static final String CONTEXT_SCOPED_ATTRIBUTES = "context_scoped_attributes/development";
 
   public static final Map<String, Class<?>> EXPERIMENTAL_PROPERTIES;
 
   static {
     EXPERIMENTAL_PROPERTIES = new HashMap<>();
     EXPERIMENTAL_PROPERTIES.put(METER_CONFIGURATOR, ExperimentalMeterConfiguratorModel.class);
     EXPERIMENTAL_PROPERTIES.put(VIEW_MATCHING_MODE, ExperimentalViewMatchingModeModel.class);
+    EXPERIMENTAL_PROPERTIES.put(CONTEXT_SCOPED_ATTRIBUTES, Boolean.class);
   }
 
   @Nullable
@@ -63,4 +65,17 @@ public static MeterProviderModel setViewMatchingMode(
     model.setExtensionProperty(VIEW_MATCHING_MODE, value);
     return model;
   }
+
+  @Nullable
+  public static Boolean getContextScopedAttributes(MeterProviderModel model) {
+    return ExtensionPropertyUtil.get(
+        CONTEXT_SCOPED_ATTRIBUTES, model.getExtensionProperties(), Boolean.class);
+  }
+
+  public static MeterProviderModel setContextScopedAttributes(
+      MeterProviderModel model, Boolean value) {
+    requireNonNull(value, "value");
+    model.setExtensionProperty(CONTEXT_SCOPED_ATTRIBUTES, value);
+    return model;
+  }
 }

sdk-extensions/declarative-config/src/main/java/io/opentelemetry/sdk/autoconfigure/declarativeconfig/model/internal/TracerProviderModelAccessor.java

@@ -24,12 +24,14 @@ public final class TracerProviderModelAccessor {
   private TracerProviderModelAccessor() {}
 
   static final String TRACER_CONFIGURATOR = "tracer_configurator/development";
+  static final String CONTEXT_SCOPED_ATTRIBUTES = "context_scoped_attributes/development";
 
   public static final Map<String, Class<?>> EXPERIMENTAL_PROPERTIES;
 
   static {
     EXPERIMENTAL_PROPERTIES = new HashMap<>();
     EXPERIMENTAL_PROPERTIES.put(TRACER_CONFIGURATOR, ExperimentalTracerConfiguratorModel.class);
+    EXPERIMENTAL_PROPERTIES.put(CONTEXT_SCOPED_ATTRIBUTES, Boolean.class);
   }
 
   @Nullable
@@ -47,4 +49,17 @@ public static TracerProviderModel setTracerConfigurator(
     model.setExtensionProperty(TRACER_CONFIGURATOR, value);
     return model;
   }
+
+  @Nullable
+  public static Boolean getContextScopedAttributes(TracerProviderModel model) {
+    return ExtensionPropertyUtil.get(
+        CONTEXT_SCOPED_ATTRIBUTES, model.getExtensionProperties(), Boolean.class);
+  }
+
+  public static TracerProviderModel setContextScopedAttributes(
+      TracerProviderModel model, Boolean value) {
+    requireNonNull(value, "value");
+    model.setExtensionProperty(CONTEXT_SCOPED_ATTRIBUTES, value);
+    return model;
+  }
 }