Add local and tagged correlation fields

Local fields only work in Brave and not with OpenTelemetry.

Tagged fields work both with Brave and with OpenTelemetry.

See gh-37435

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/BaggageTagSpanHandler.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2012-2023 the original author or 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
+ *
+ *      https://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.
+ */
+
+package org.springframework.boot.actuate.autoconfigure.tracing;
+
+import java.util.Collection;
+
+import brave.Tags;
+import brave.baggage.BaggageField;
+import brave.handler.MutableSpan;
+import brave.handler.SpanHandler;
+import brave.propagation.TraceContext;
+
+class BaggageTagSpanHandler extends SpanHandler {
+
+	private final Collection<BaggageField> fieldsToTag;
+
+	BaggageTagSpanHandler(Collection<BaggageField> fieldsToTag) {
+		this.fieldsToTag = fieldsToTag;
+	}
+
+	@Override
+	public boolean end(TraceContext context, MutableSpan span, Cause cause) {
+		for (BaggageField field : this.fieldsToTag) {
+			Tags.BAGGAGE_FIELD.tag(field, context, span);
+		}
+		return true;
+	}
+
+}

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/BravePropagationConfigurations.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,6 +27,7 @@ import brave.baggage.CorrelationScopeConfig.SingleCorrelationField;
 import brave.baggage.CorrelationScopeCustomizer;
 import brave.baggage.CorrelationScopeDecorator;
 import brave.context.slf4j.MDCScopeDecorator;
+import brave.handler.SpanHandler;
 import brave.propagation.CurrentTraceContext.ScopeDecorator;
 import brave.propagation.Propagation;
 import brave.propagation.Propagation.Factory;
@@ -40,6 +41,7 @@ import org.springframework.boot.context.properties.EnableConfigurationProperties
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.annotation.Order;
+import org.springframework.util.CollectionUtils;
 
 /**
  * Brave propagation configurations. They are imported by {@link BraveAutoConfiguration}.
@@ -120,6 +122,27 @@ class BravePropagationConfigurations {
 			};
 		}
 
+		@Bean
+		@Order(1)
+		BaggagePropagationCustomizer localFieldsBaggagePropagationCustomizer() {
+			return (builder) -> {
+				List<String> localFields = this.tracingProperties.getBaggage().getLocalFields();
+				for (String localFieldName : localFields) {
+					builder.add(BaggagePropagationConfig.SingleBaggageField.local(BaggageField.create(localFieldName)));
+				}
+			};
+		}
+
+		@Bean
+		@Order(2)
+		SpanHandler baggageTagSpanHandler() {
+			List<String> tagFields = this.tracingProperties.getBaggage().getTagFields();
+			if (CollectionUtils.isEmpty(tagFields)) {
+				return SpanHandler.NOOP;
+			}
+			return new BaggageTagSpanHandler(tagFields.stream().map(BaggageField::create).toList());
+		}
+
 		@Bean
 		@ConditionalOnMissingBean
 		@ConditionalOnEnabledTracing

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/OpenTelemetryAutoConfiguration.java

@@ -16,7 +16,6 @@
 
 package org.springframework.boot.actuate.autoconfigure.tracing;
 
-import java.util.Collections;
 import java.util.List;
 
 import io.micrometer.tracing.SpanCustomizer;
@@ -47,6 +46,8 @@ import io.opentelemetry.sdk.trace.export.BatchSpanProcessor;
 import io.opentelemetry.sdk.trace.export.BatchSpanProcessorBuilder;
 import io.opentelemetry.sdk.trace.export.SpanExporter;
 import io.opentelemetry.sdk.trace.samplers.Sampler;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.SpringBootVersion;
@@ -57,6 +58,7 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Import;
+import org.springframework.util.CollectionUtils;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for OpenTelemetry tracing.
@@ -75,10 +77,15 @@ import org.springframework.context.annotation.Import;
 		OpenTelemetryPropagationConfigurations.NoPropagation.class })
 public class OpenTelemetryAutoConfiguration {
 
+	private static final Log logger = LogFactory.getLog(OpenTelemetryAutoConfiguration.class);
+
 	private final TracingProperties tracingProperties;
 
 	OpenTelemetryAutoConfiguration(TracingProperties tracingProperties) {
 		this.tracingProperties = tracingProperties;
+		if (!CollectionUtils.isEmpty(this.tracingProperties.getBaggage().getLocalFields())) {
+			logger.warn("Local fields are not supported when using OpenTelemetry!");
+		}
 	}
 
 	@Bean
@@ -137,9 +144,10 @@ public class OpenTelemetryAutoConfiguration {
 	@ConditionalOnMissingBean(io.micrometer.tracing.Tracer.class)
 	OtelTracer micrometerOtelTracer(Tracer tracer, EventPublisher eventPublisher,
 			OtelCurrentTraceContext otelCurrentTraceContext) {
+		List<String> remoteFields = this.tracingProperties.getBaggage().getRemoteFields();
+		List<String> tagFields = this.tracingProperties.getBaggage().getTagFields();
 		return new OtelTracer(tracer, otelCurrentTraceContext, eventPublisher,
-				new OtelBaggageManager(otelCurrentTraceContext, this.tracingProperties.getBaggage().getRemoteFields(),
-						Collections.emptyList()));
+				new OtelBaggageManager(otelCurrentTraceContext, remoteFields, tagFields));
 	}
 
 	@Bean

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/OpenTelemetryPropagationConfigurations.java

@@ -16,7 +16,6 @@
 
 package org.springframework.boot.actuate.autoconfigure.tracing;
 
-import java.util.Collections;
 import java.util.List;
 
 import io.micrometer.tracing.otel.bridge.OtelBaggageManager;
@@ -73,8 +72,9 @@ class OpenTelemetryPropagationConfigurations {
 		@ConditionalOnEnabledTracing
 		TextMapPropagator textMapPropagatorWithBaggage(OtelCurrentTraceContext otelCurrentTraceContext) {
 			List<String> remoteFields = this.tracingProperties.getBaggage().getRemoteFields();
+			List<String> tagFields = this.tracingProperties.getBaggage().getTagFields();
 			BaggageTextMapPropagator baggagePropagator = new BaggageTextMapPropagator(remoteFields,
-					new OtelBaggageManager(otelCurrentTraceContext, remoteFields, Collections.emptyList()));
+					new OtelBaggageManager(otelCurrentTraceContext, remoteFields, tagFields));
 			return CompositeTextMapPropagator.create(this.tracingProperties.getPropagation(), baggagePropagator);
 		}
 

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/TracingProperties.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -103,6 +103,17 @@ public class TracingProperties {
 		 */
 		private List<String> remoteFields = new ArrayList<>();
 
+		/**
+		 * List of fields that should be accessible within the JVM process but not
+		 * propagated over the wire. Local fields are not supported with OpenTelemetry.
+		 */
+		private List<String> localFields = new ArrayList<>();
+
+		/**
+		 * List of fields that should automatically become tags.
+		 */
+		private List<String> tagFields = new ArrayList<>();
+
 		public boolean isEnabled() {
 			return this.enabled;
 		}
@@ -123,10 +134,26 @@ public class TracingProperties {
 			return this.remoteFields;
 		}
 
+		public List<String> getLocalFields() {
+			return this.localFields;
+		}
+
+		public List<String> getTagFields() {
+			return this.tagFields;
+		}
+
 		public void setRemoteFields(List<String> remoteFields) {
 			this.remoteFields = remoteFields;
 		}
 
+		public void setLocalFields(List<String> localFields) {
+			this.localFields = localFields;
+		}
+
+		public void setTagFields(List<String> tagFields) {
+			this.tagFields = tagFields;
+		}
+
 		public static class Correlation {
 
 			/**

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/tracing/BaggagePropagationIntegrationTests.java

@@ -227,6 +227,16 @@ class BaggagePropagationIntegrationTests {
 							"management.tracing.baggage.remote-fields=x-vcap-request-id,country-code,bp",
 							"management.tracing.baggage.correlation.fields=country-code,bp");
 			}
+		},
+
+		BRAVE_LOCAL_FIELDS {
+			@Override
+			public ApplicationContextRunner get() {
+				return new ApplicationContextRunner()
+					.withConfiguration(AutoConfigurations.of(BraveAutoConfiguration.class))
+					.withPropertyValues("management.tracing.baggage.local-fields=country-code,bp",
+							"management.tracing.baggage.correlation.fields=country-code,bp");
+			}
 		}
 
 	}

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/tracing/BraveAutoConfigurationTests.java

@@ -26,6 +26,7 @@ import brave.Span;
 import brave.SpanCustomizer;
 import brave.Tracer;
 import brave.Tracing;
+import brave.baggage.BaggageField;
 import brave.baggage.BaggagePropagation;
 import brave.baggage.CorrelationScopeConfig.SingleCorrelationField;
 import brave.handler.SpanHandler;
@@ -344,6 +345,22 @@ class BraveAutoConfigurationTests {
 		});
 	}
 
+	@Test
+	void shouldCreateTagHandler() {
+		this.contextRunner.withPropertyValues("management.tracing.baggage.tag-fields=country-code,bp")
+			.run((context) -> assertThat(context.getBean(BaggageTagSpanHandler.class)).extracting("fieldsToTag")
+				.asInstanceOf(InstanceOfAssertFactories.list(BaggageField.class))
+				.extracting(BaggageField::name)
+				.containsExactlyInAnyOrder("country-code", "bp"));
+	}
+
+	@Test
+	void noopOnNoTagFields() {
+		this.contextRunner.withPropertyValues("management.tracing.baggage.tag-fields=")
+			.run((context) -> assertThat(context.getBean("baggageTagSpanHandler", SpanHandler.class))
+				.isSameAs(SpanHandler.NOOP));
+	}
+
 	@Test
 	void shouldDisablePropagationIfTracingIsDisabled() {
 		this.contextRunner.withPropertyValues("management.tracing.enabled=false").run((context) -> {

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/tracing/OpenTelemetryAutoConfigurationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -51,6 +51,7 @@ import io.opentelemetry.sdk.trace.data.SpanData;
 import io.opentelemetry.sdk.trace.export.SpanExporter;
 import io.opentelemetry.sdk.trace.samplers.Sampler;
 import io.opentelemetry.semconv.ResourceAttributes;
+import org.assertj.core.api.InstanceOfAssertFactories;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
@@ -272,6 +273,22 @@ class OpenTelemetryAutoConfigurationTests {
 		});
 	}
 
+	@Test
+	void shouldConfigureRemoteAndTaggedFields() {
+		this.contextRunner
+			.withPropertyValues("management.tracing.baggage.remote-fields=r1",
+					"management.tracing.baggage.tag-fields=t1")
+			.run((context) -> {
+				CompositeTextMapPropagator propagator = context.getBean(CompositeTextMapPropagator.class);
+				assertThat(propagator).extracting("baggagePropagator.baggageManager.remoteFields")
+					.asInstanceOf(InstanceOfAssertFactories.list(String.class))
+					.containsExactly("r1");
+				assertThat(propagator).extracting("baggagePropagator.baggageManager.tagFields")
+					.asInstanceOf(InstanceOfAssertFactories.list(String.class))
+					.containsExactly("t1");
+			});
+	}
+
 	@Test
 	void shouldCustomizeSdkTracerProvider() {
 		this.contextRunner.withUserConfiguration(SdkTracerProviderCustomizationConfiguration.class).run((context) -> {