[Observability] MDC, Context Propagation (via B3 and W3C) and Baggage

Separated baggage from mdc

Removed unused zipkin property

Added more tests

Added more Brave tests

Lowered the scope of the PR

Added missing spring configuration metadata entries

Applied a change of javadocs

Added tests

Changed the property source name for tracing environment post processor

Custom propagation & OTel

Custom propagation & Brave

WIP with tests

Polish

Fixed checkstyle

Enable Brave tests and fix OTel's static initializer issue
Since we used the Context class for Brave tests too (assertThat(Context.current()).isEqualTo(Context.root());) the Context class was loaded during Brave tests which triggered the static initialization of the ContextStorage. At that point since the OTel beans were not created and the ContextStorage wrapper was not registered, OTel defaults  were used instead of ours

Remove unnecessary @DirtiesContext

Improve asserts

Bypassing ApplicationEventPublisher and refactoring tests

Fighting to make OTel baggage work

WIP

WIP on OTel tests

Uncommented Brave test

Added OTel and uses snapshots for tracing

Author: marcingrzejszczak

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

@@ -21,6 +21,14 @@
 import brave.Tracing;
 import brave.Tracing.Builder;
 import brave.TracingCustomizer;
+import brave.baggage.BaggageField;
+import brave.baggage.BaggagePropagation;
+import brave.baggage.BaggagePropagationConfig;
+import brave.baggage.BaggagePropagationCustomizer;
+import brave.baggage.CorrelationScopeConfig;
+import brave.baggage.CorrelationScopeCustomizer;
+import brave.baggage.CorrelationScopeDecorator;
+import brave.context.slf4j.MDCScopeDecorator;
 import brave.handler.SpanHandler;
 import brave.http.HttpClientHandler;
 import brave.http.HttpClientRequest;
@@ -33,19 +41,27 @@
 import brave.propagation.CurrentTraceContext;
 import brave.propagation.CurrentTraceContext.ScopeDecorator;
 import brave.propagation.CurrentTraceContextCustomizer;
+import brave.propagation.Propagation;
 import brave.propagation.Propagation.Factory;
 import brave.propagation.ThreadLocalCurrentTraceContext;
 import brave.sampler.Sampler;
 import io.micrometer.tracing.brave.bridge.BraveBaggageManager;
 import io.micrometer.tracing.brave.bridge.BraveCurrentTraceContext;
 import io.micrometer.tracing.brave.bridge.BraveHttpClientHandler;
 import io.micrometer.tracing.brave.bridge.BraveHttpServerHandler;
+import io.micrometer.tracing.brave.bridge.BravePropagator;
 import io.micrometer.tracing.brave.bridge.BraveTracer;
+import io.micrometer.tracing.brave.bridge.W3CPropagation;
+import org.slf4j.MDC;
 
+import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -55,6 +71,7 @@
  * {@link EnableAutoConfiguration Auto-configuration} for Brave.
  *
  * @author Moritz Halbritter
+ * @author Marcin Grzejszczak
  * @since 3.0.0
  */
 @AutoConfiguration(before = MicrometerTracingAutoConfiguration.class)
@@ -105,12 +122,6 @@ public CurrentTraceContext braveCurrentTraceContext(List<CurrentTraceContext.Sco
 		return builder.build();
 	}
 
-	@Bean
-	@ConditionalOnMissingBean
-	public Factory bravePropagationFactory() {
-		return B3Propagation.newFactoryBuilder().injectFormat(B3Propagation.Format.SINGLE_NO_PARENT).build();
-	}
-
 	@Bean
 	@ConditionalOnMissingBean
 	public Sampler braveSampler(TracingProperties properties) {
@@ -135,21 +146,35 @@ public HttpClientHandler<HttpClientRequest, HttpClientResponse> httpClientHandle
 		return HttpClientHandler.create(httpTracing);
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	@ConditionalOnMissingClass("io.micrometer.tracing.brave.bridge.BraveTracer")
+	static class BraveMicrometerMissing {
+
+		@Bean
+		@ConditionalOnMissingBean
+		@ConditionalOnProperty(value = "management.tracing.propagation.type", havingValue = "B3", matchIfMissing = true)
+		Factory bravePropagationFactory() {
+			return B3Propagation.newFactoryBuilder().injectFormat(B3Propagation.Format.SINGLE_NO_PARENT).build();
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	@ConditionalOnClass(BraveTracer.class)
 	static class BraveMicrometer {
 
+		private static final BraveBaggageManager BRAVE_BAGGAGE_MANAGER = new BraveBaggageManager();
+
 		@Bean
 		@ConditionalOnMissingBean
-		BraveTracer braveTracerBridge(brave.Tracer tracer, CurrentTraceContext currentTraceContext,
-				BraveBaggageManager braveBaggageManager) {
-			return new BraveTracer(tracer, new BraveCurrentTraceContext(currentTraceContext), braveBaggageManager);
+		BraveTracer braveTracerBridge(brave.Tracer tracer, CurrentTraceContext currentTraceContext) {
+			return new BraveTracer(tracer, new BraveCurrentTraceContext(currentTraceContext), BRAVE_BAGGAGE_MANAGER);
 		}
 
 		@Bean
 		@ConditionalOnMissingBean
-		BraveBaggageManager braveBaggageManager() {
-			return new BraveBaggageManager();
+		BravePropagator bravePropagator(Tracing tracing) {
+			return new BravePropagator(tracing);
 		}
 
 		@Bean
@@ -166,6 +191,101 @@ BraveHttpClientHandler braveHttpClientHandler(
 			return new BraveHttpClientHandler(httpClientHandler);
 		}
 
+		@Configuration(proxyBeanMethods = false)
+		@ConditionalOnProperty(value = "management.tracing.baggage.enabled", havingValue = "false",
+				matchIfMissing = true)
+		static class BraveNoBaggageConfiguration {
+
+			@Bean
+			@ConditionalOnMissingBean
+			@ConditionalOnProperty(value = "management.tracing.propagation.type", havingValue = "W3C",
+					matchIfMissing = true)
+			Factory w3cPropagationNoBaggageFactory() {
+				return new W3CPropagation(BRAVE_BAGGAGE_MANAGER, List.of()); // TODO: Use
+																				// snapshots
+																				// of
+																				// tracing
+																				// to not
+																				// use
+																				// baggage
+																				// for W3C
+			}
+
+			@Bean
+			@ConditionalOnMissingBean
+			@ConditionalOnProperty(value = "management.tracing.propagation.type", havingValue = "B3")
+			Factory b3PropagationNoBaggageFactory() {
+				return B3Propagation.newFactoryBuilder().injectFormat(B3Propagation.Format.SINGLE_NO_PARENT).build();
+			}
+
+		}
+
+		@Configuration(proxyBeanMethods = false)
+		@ConditionalOnProperty(value = "management.tracing.baggage.enabled", matchIfMissing = true)
+		static class BraveBaggageConfiguration {
+
+			@Bean
+			@ConditionalOnMissingBean
+			@ConditionalOnProperty(value = "management.tracing.propagation.type", havingValue = "W3C",
+					matchIfMissing = true)
+			BaggagePropagation.FactoryBuilder w3cPropagationFactory() {
+				return BaggagePropagation.newFactoryBuilder(new W3CPropagation(BRAVE_BAGGAGE_MANAGER, List.of()));
+			}
+
+			@Bean
+			@ConditionalOnMissingBean
+			@ConditionalOnProperty(value = "management.tracing.propagation.type", havingValue = "B3")
+			BaggagePropagation.FactoryBuilder b3PropagationFactory() {
+				return BaggagePropagation.newFactoryBuilder(
+						B3Propagation.newFactoryBuilder().injectFormat(B3Propagation.Format.SINGLE_NO_PARENT).build());
+			}
+
+			@Bean
+			@ConditionalOnMissingBean
+			Propagation.Factory micrometerTracingPropagationWithBaggage(
+					BaggagePropagation.FactoryBuilder factoryBuilder, TracingProperties tracingProperties,
+					ObjectProvider<List<BaggagePropagationCustomizer>> baggagePropagationCustomizers) {
+				List<String> remoteFields = tracingProperties.getBaggage().getRemoteFields();
+				for (String fieldName : remoteFields) {
+					factoryBuilder
+							.add(BaggagePropagationConfig.SingleBaggageField.remote(BaggageField.create(fieldName)));
+				}
+				baggagePropagationCustomizers.ifAvailable(
+						(customizers) -> customizers.forEach((customizer) -> customizer.customize(factoryBuilder)));
+				return factoryBuilder.build();
+			}
+
+			@Bean
+			@ConditionalOnMissingBean(CorrelationScopeDecorator.class)
+			@ConditionalOnBean(CorrelationScopeDecorator.Builder.class)
+			@ConditionalOnProperty(value = "management.tracing.baggage.correlation-enabled", matchIfMissing = true)
+			ScopeDecorator correlationScopeDecorator(TracingProperties properties,
+					ObjectProvider<List<CorrelationScopeCustomizer>> correlationScopeCustomizers,
+					CorrelationScopeDecorator.Builder builder) {
+				List<String> correlationFields = properties.getBaggage().getCorrelationFields();
+				for (String field : correlationFields) {
+					builder.add(CorrelationScopeConfig.SingleCorrelationField.newBuilder(BaggageField.create(field))
+							.flushOnUpdate().build());
+				}
+				correlationScopeCustomizers.ifAvailable(
+						(customizers) -> customizers.forEach((customizer) -> customizer.customize(builder)));
+				return builder.build();
+			}
+
+		}
+
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	static class CorrelationScopeDecoratorConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean
+		@ConditionalOnClass(MDC.class)
+		CorrelationScopeDecorator.Builder mdcCorrelationScopeDecoratorBuilder() {
+			return MDCScopeDecorator.newBuilder();
+		}
+
 	}
 
 }