Auto-configure SpanTagAnnotationHandler

Closes gh-38662

Author: mhalbritter

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/MicrometerTracingAutoConfiguration.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.
@@ -16,6 +16,7 @@
 
 package org.springframework.boot.actuate.autoconfigure.tracing;
 
+import io.micrometer.common.annotation.ValueExpressionResolver;
 import io.micrometer.tracing.Tracer;
 import io.micrometer.tracing.annotation.DefaultNewSpanParser;
 import io.micrometer.tracing.annotation.ImperativeMethodInvocationProcessor;
@@ -29,7 +30,7 @@
 import io.micrometer.tracing.propagation.Propagator;
 import org.aspectj.weaver.Advice;
 
-import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.beans.factory.BeanFactory;
 import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
@@ -39,6 +40,10 @@
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
+import org.springframework.expression.Expression;
+import org.springframework.expression.ExpressionParser;
+import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.expression.spel.support.SimpleEvaluationContext;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for the Micrometer Tracing API.
@@ -104,14 +109,18 @@ DefaultNewSpanParser newSpanParser() {
 			return new DefaultNewSpanParser();
 		}
 
+		@Bean
+		@ConditionalOnMissingBean
+		SpanTagAnnotationHandler spanTagAnnotationHandler(BeanFactory beanFactory) {
+			ValueExpressionResolver valueExpressionResolver = new SpelTagValueExpressionResolver();
+			return new SpanTagAnnotationHandler(beanFactory::getBean, (ignored) -> valueExpressionResolver);
+		}
+
 		@Bean
 		@ConditionalOnMissingBean(MethodInvocationProcessor.class)
 		ImperativeMethodInvocationProcessor imperativeMethodInvocationProcessor(NewSpanParser newSpanParser,
-				Tracer tracer, ObjectProvider<SpanTagAnnotationHandler> spanTagAnnotationHandler) {
-			ImperativeMethodInvocationProcessor methodInvocationProcessor = new ImperativeMethodInvocationProcessor(
-					newSpanParser, tracer);
-			spanTagAnnotationHandler.ifAvailable(methodInvocationProcessor::setSpanTagAnnotationHandler);
-			return methodInvocationProcessor;
+				Tracer tracer, SpanTagAnnotationHandler spanTagAnnotationHandler) {
+			return new ImperativeMethodInvocationProcessor(newSpanParser, tracer, spanTagAnnotationHandler);
 		}
 
 		@Bean
@@ -122,4 +131,21 @@ SpanAspect spanAspect(MethodInvocationProcessor methodInvocationProcessor) {
 
 	}
 
+	private static class SpelTagValueExpressionResolver implements ValueExpressionResolver {
+
+		@Override
+		public String resolve(String expression, Object parameter) {
+			try {
+				SimpleEvaluationContext context = SimpleEvaluationContext.forReadOnlyDataBinding().build();
+				ExpressionParser expressionParser = new SpelExpressionParser();
+				Expression expressionToEvaluate = expressionParser.parseExpression(expression);
+				return expressionToEvaluate.getValue(context, parameter, String.class);
+			}
+			catch (Exception ex) {
+				throw new IllegalStateException("Unable to evaluate SpEL expression '%s'".formatted(expression), ex);
+			}
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/tracing/MicrometerTracingAutoConfigurationTests.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.
@@ -18,6 +18,8 @@
 
 import java.util.List;
 
+import io.micrometer.common.annotation.ValueExpressionResolver;
+import io.micrometer.common.annotation.ValueResolver;
 import io.micrometer.tracing.Tracer;
 import io.micrometer.tracing.annotation.DefaultNewSpanParser;
 import io.micrometer.tracing.annotation.ImperativeMethodInvocationProcessor;
@@ -63,6 +65,7 @@ void shouldSupplyBeans() {
 				assertThat(context).hasSingleBean(DefaultNewSpanParser.class);
 				assertThat(context).hasSingleBean(ImperativeMethodInvocationProcessor.class);
 				assertThat(context).hasSingleBean(SpanAspect.class);
+				assertThat(context).hasSingleBean(SpanTagAnnotationHandler.class);
 			});
 	}
 
@@ -100,6 +103,8 @@ void shouldBackOffOnCustomBeans() {
 				assertThat(context).hasSingleBean(ImperativeMethodInvocationProcessor.class);
 				assertThat(context).hasBean("customSpanAspect");
 				assertThat(context).hasSingleBean(SpanAspect.class);
+				assertThat(context).hasBean("customSpanTagAnnotationHandler");
+				assertThat(context).hasSingleBean(SpanTagAnnotationHandler.class);
 			});
 	}
 
@@ -215,6 +220,12 @@ SpanAspect customSpanAspect(MethodInvocationProcessor methodInvocationProcessor)
 			return new SpanAspect(methodInvocationProcessor);
 		}
 
+		@Bean
+		SpanTagAnnotationHandler customSpanTagAnnotationHandler() {
+			return new SpanTagAnnotationHandler((aClass) -> mock(ValueResolver.class),
+					(aClass) -> mock(ValueExpressionResolver.class));
+		}
+
 	}
 
 	@Configuration(proxyBeanMethods = false)