Auto-configure remote fields on BraveBaggageManager

Closes gh-41884

Author: mhalbritter

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

@@ -155,7 +155,8 @@ Sampler braveSampler() {
 	@ConditionalOnMissingBean(io.micrometer.tracing.Tracer.class)
 	BraveTracer braveTracerBridge(brave.Tracer tracer, CurrentTraceContext currentTraceContext) {
 		return new BraveTracer(tracer, new BraveCurrentTraceContext(currentTraceContext),
-				new BraveBaggageManager(this.tracingProperties.getBaggage().getTagFields()));
+				new BraveBaggageManager(this.tracingProperties.getBaggage().getTagFields(),
+						this.tracingProperties.getBaggage().getRemoteFields()));
 	}
 
 	@Bean

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

@@ -91,7 +91,8 @@ BaggagePropagation.FactoryBuilder propagationFactoryBuilder(
 				.forEach((customizer) -> customizer.customize(throwAwayBuilder));
 			CompositePropagationFactory propagationFactory = CompositePropagationFactory.create(
 					this.tracingProperties.getPropagation(),
-					new BraveBaggageManager(this.tracingProperties.getBaggage().getTagFields()),
+					new BraveBaggageManager(this.tracingProperties.getBaggage().getTagFields(),
+							this.tracingProperties.getBaggage().getRemoteFields()),
 					LocalBaggageFields.extractFrom(throwAwayBuilder));
 			FactoryBuilder builder = BaggagePropagation.newFactoryBuilder(propagationFactory);
 			throwAwayBuilder.configs().forEach(builder::add);

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

@@ -35,6 +35,9 @@
 import brave.propagation.Propagation.Factory;
 import brave.propagation.TraceContext;
 import brave.sampler.Sampler;
+import io.micrometer.observation.Observation;
+import io.micrometer.observation.Observation.Scope;
+import io.micrometer.observation.ObservationRegistry;
 import io.micrometer.tracing.brave.bridge.BraveBaggageManager;
 import io.micrometer.tracing.brave.bridge.BraveSpanCustomizer;
 import io.micrometer.tracing.brave.bridge.BraveTracer;
@@ -47,6 +50,7 @@
 import org.assertj.core.api.InstanceOfAssertFactories;
 import org.junit.jupiter.api.Test;
 
+import org.springframework.boot.actuate.autoconfigure.observation.ObservationAutoConfiguration;
 import org.springframework.boot.actuate.autoconfigure.tracing.BraveAutoConfigurationTests.SpanHandlerConfiguration.AdditionalSpanHandler;
 import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.context.properties.IncompatibleConfigurationException;
@@ -364,6 +368,29 @@ void shouldConfigureTaggedFields() {
 		});
 	}
 
+	@Test
+	void keysAreSetInBaggage() {
+		this.contextRunner
+			.withConfiguration(
+					AutoConfigurations.of(ObservationAutoConfiguration.class, MicrometerTracingAutoConfiguration.class))
+			.withPropertyValues("management.tracing.baggage.remote-fields=f1,f2")
+			.run((context) -> {
+				BraveTracer braveTracer = context.getBean(BraveTracer.class);
+				ObservationRegistry observationRegistry = context.getBean(ObservationRegistry.class);
+				Observation observation = Observation.start("o1", observationRegistry)
+					.lowCardinalityKeyValue("f1", "v1")
+					.highCardinalityKeyValue("f2", "v2");
+				Map<String, String> baggage = braveTracer.getAllBaggage();
+				assertThat(baggage).isEmpty();
+				try (Scope ignore = observation.openScope()) {
+					baggage = braveTracer.getAllBaggage();
+					assertThat(baggage).containsAllEntriesOf(Map.of("f1", "v1", "f2", "v2"));
+				}
+				baggage = braveTracer.getAllBaggage();
+				assertThat(baggage).isEmpty();
+			});
+	}
+
 	private void injectToMap(Map<String, String> map, String key, String value) {
 		map.put(key, value);
 	}