Allow reusing registered global OpenTelemetry

spring-boot-project/spring-boot-opentelemetry/src/main/java/org/springframework/boot/opentelemetry/autoconfigure/OpenTelemetryProperties.java

@@ -25,16 +25,30 @@
  * Configuration properties for OpenTelemetry.
  *
  * @author Moritz Halbritter
+ * @author Yanming Zhou
  * @since 4.0.0
  */
 @ConfigurationProperties("management.opentelemetry")
 public class OpenTelemetryProperties {
 
+	/**
+	 * Whether to reuse registered global OpenTelemetry.
+	 */
+	private boolean reuseRegisteredGlobal;
+
 	/**
 	 * Resource attributes.
 	 */
 	private Map<String, String> resourceAttributes = new HashMap<>();
 
+	public boolean isReuseRegisteredGlobal() {
+		return this.reuseRegisteredGlobal;
+	}
+
+	public void setReuseRegisteredGlobal(boolean reuseRegisteredGlobal) {
+		this.reuseRegisteredGlobal = reuseRegisteredGlobal;
+	}
+
 	public Map<String, String> getResourceAttributes() {
 		return this.resourceAttributes;
 	}

spring-boot-project/spring-boot-opentelemetry/src/main/java/org/springframework/boot/opentelemetry/autoconfigure/OpenTelemetrySdkAutoConfiguration.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.opentelemetry.autoconfigure;
 
+import io.opentelemetry.api.GlobalOpenTelemetry;
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.context.propagation.ContextPropagators;
 import io.opentelemetry.sdk.OpenTelemetrySdk;
@@ -33,17 +34,25 @@
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionMessage;
+import org.springframework.boot.autoconfigure.condition.ConditionOutcome;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBooleanProperty;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ConditionContext;
+import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.env.Environment;
+import org.springframework.core.type.AnnotatedTypeMetadata;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for the OpenTelemetry SDK.
  *
  * @author Moritz Halbritter
+ * @author Yanming Zhou
  * @since 4.0.0
  */
 @AutoConfiguration
@@ -54,6 +63,14 @@ public class OpenTelemetrySdkAutoConfiguration {
 	OpenTelemetrySdkAutoConfiguration() {
 	}
 
+	@Bean
+	@ConditionalOnMissingBean(OpenTelemetry.class)
+	@ConditionalOnBooleanProperty("management.opentelemetry.reuse-registered-global")
+	@Conditional(OnRegisteredGlobalOpenTelemetryCondition.class)
+	OpenTelemetry globalOpenTelemetry() {
+		return GlobalOpenTelemetry.get();
+	}
+
 	@Bean
 	@ConditionalOnMissingBean(OpenTelemetry.class)
 	OpenTelemetrySdk openTelemetrySdk(ObjectProvider<SdkTracerProvider> openTelemetrySdkTracerProvider,
@@ -106,4 +123,15 @@ SdkLoggerProvider openTelemetrySdkLoggerProvider(Resource openTelemetryResource,
 
 	}
 
+	static class OnRegisteredGlobalOpenTelemetryCondition extends SpringBootCondition {
+
+		@Override
+		public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
+			boolean globalOpenTelemetryRegistered = GlobalOpenTelemetry.get() != OpenTelemetry.noop();
+			return new ConditionOutcome(globalOpenTelemetryRegistered, ConditionMessage
+				.of("GlobalOpenTelemetry is" + (globalOpenTelemetryRegistered ? "" : " not") + " registered"));
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-opentelemetry/src/test/java/org/springframework/boot/opentelemetry/autoconfigure/OpenTelemetrySdkAutoConfigurationTests.java

@@ -19,8 +19,11 @@
 import java.util.Collection;
 import java.util.concurrent.atomic.AtomicInteger;
 
+import io.opentelemetry.api.GlobalOpenTelemetry;
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.api.common.AttributeKey;
+import io.opentelemetry.api.trace.Tracer;
+import io.opentelemetry.api.trace.TracerProvider;
 import io.opentelemetry.context.Context;
 import io.opentelemetry.context.propagation.ContextPropagators;
 import io.opentelemetry.sdk.OpenTelemetrySdk;
@@ -49,6 +52,8 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.entry;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.BDDMockito.given;
 import static org.mockito.Mockito.mock;
 
 /**
@@ -57,6 +62,7 @@
  * @author Moritz Halbritter
  * @author Toshiaki Maki
  * @author Phillip Webb
+ * @author Yanming Zhou
  */
 class OpenTelemetrySdkAutoConfigurationTests {
 
@@ -240,6 +246,21 @@ void whenHasMultipleSdkLoggerProviderBuilderCustomizersCallsCustomizeMethod() {
 			});
 	}
 
+	@Test
+	void reuseRegisteredGlobalOpenTelemetry() {
+		OpenTelemetry openTelemetry = mock(OpenTelemetry.class);
+		TracerProvider tracerProvider = mock(TracerProvider.class);
+		Tracer tracer = mock(Tracer.class);
+		given(tracerProvider.get(eq("org.springframework.boot"))).willReturn(tracer);
+		given(openTelemetry.getTracerProvider()).willReturn(tracerProvider);
+		GlobalOpenTelemetry.set(openTelemetry);
+		this.contextRunner.withPropertyValues("management.opentelemetry.reuse-registered-global=true")
+			.run((context) -> {
+				assertThat(context).doesNotHaveBean(OpenTelemetrySdk.class);
+				assertThat(context.getBean(OpenTelemetry.class).getTracer("org.springframework.boot")).isSameAs(tracer);
+			});
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class UserConfiguration {