Add ObservationFilter beans to auto-configured ObservationRegistry

Fixes gh-33968

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/observation/ObservationAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * 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.
@@ -23,6 +23,7 @@ import io.micrometer.core.instrument.observation.DefaultMeterObservationHandler;
 import io.micrometer.core.instrument.observation.MeterObservationHandler;
 import io.micrometer.observation.GlobalObservationConvention;
 import io.micrometer.observation.Observation;
+import io.micrometer.observation.ObservationFilter;
 import io.micrometer.observation.ObservationHandler;
 import io.micrometer.observation.ObservationPredicate;
 import io.micrometer.observation.ObservationRegistry;
@@ -62,9 +63,10 @@ public class ObservationAutoConfiguration {
 			ObjectProvider<ObservationPredicate> observationPredicates,
 			ObjectProvider<GlobalObservationConvention<?>> observationConventions,
 			ObjectProvider<ObservationHandler<?>> observationHandlers,
-			ObjectProvider<ObservationHandlerGrouping> observationHandlerGrouping) {
+			ObjectProvider<ObservationHandlerGrouping> observationHandlerGrouping,
+			ObjectProvider<ObservationFilter> observationFilters) {
 		return new ObservationRegistryPostProcessor(observationRegistryCustomizers, observationPredicates,
-				observationConventions, observationHandlers, observationHandlerGrouping);
+				observationConventions, observationHandlers, observationHandlerGrouping, observationFilters);
 	}
 
 	@Bean

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/observation/ObservationRegistryConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * 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.
@@ -19,6 +19,7 @@ package org.springframework.boot.actuate.autoconfigure.observation;
 import java.util.List;
 
 import io.micrometer.observation.GlobalObservationConvention;
+import io.micrometer.observation.ObservationFilter;
 import io.micrometer.observation.ObservationHandler;
 import io.micrometer.observation.ObservationPredicate;
 import io.micrometer.observation.ObservationRegistry;
@@ -48,22 +49,27 @@ class ObservationRegistryConfigurer {
 
 	private final ObjectProvider<ObservationHandlerGrouping> observationHandlerGrouping;
 
+	private final ObjectProvider<ObservationFilter> observationFilters;
+
 	ObservationRegistryConfigurer(ObjectProvider<ObservationRegistryCustomizer<?>> customizers,
 			ObjectProvider<ObservationPredicate> observationPredicates,
 			ObjectProvider<GlobalObservationConvention<?>> observationConventions,
 			ObjectProvider<ObservationHandler<?>> observationHandlers,
-			ObjectProvider<ObservationHandlerGrouping> observationHandlerGrouping) {
+			ObjectProvider<ObservationHandlerGrouping> observationHandlerGrouping,
+			ObjectProvider<ObservationFilter> observationFilters) {
 		this.customizers = customizers;
 		this.observationPredicates = observationPredicates;
 		this.observationConventions = observationConventions;
 		this.observationHandlers = observationHandlers;
 		this.observationHandlerGrouping = observationHandlerGrouping;
+		this.observationFilters = observationFilters;
 	}
 
 	void configure(ObservationRegistry registry) {
 		registerObservationPredicates(registry);
 		registerGlobalObservationConventions(registry);
 		registerHandlers(registry);
+		registerFilters(registry);
 		customize(registry);
 	}
 
@@ -80,6 +86,10 @@ class ObservationRegistryConfigurer {
 		this.observationConventions.orderedStream().forEach(registry.observationConfig()::observationConvention);
 	}
 
+	private void registerFilters(ObservationRegistry registry) {
+		this.observationFilters.orderedStream().forEach(registry.observationConfig()::observationFilter);
+	}
+
 	@SuppressWarnings("unchecked")
 	private void customize(ObservationRegistry registry) {
 		LambdaSafe.callbacks(ObservationRegistryCustomizer.class, asOrderedList(this.customizers), registry)

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/observation/ObservationRegistryPostProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * 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.
@@ -17,6 +17,7 @@
 package org.springframework.boot.actuate.autoconfigure.observation;
 
 import io.micrometer.observation.GlobalObservationConvention;
+import io.micrometer.observation.ObservationFilter;
 import io.micrometer.observation.ObservationHandler;
 import io.micrometer.observation.ObservationPredicate;
 import io.micrometer.observation.ObservationRegistry;
@@ -44,18 +45,22 @@ class ObservationRegistryPostProcessor implements BeanPostProcessor {
 
 	private final ObjectProvider<ObservationHandlerGrouping> observationHandlerGrouping;
 
+	private final ObjectProvider<ObservationFilter> observationFilters;
+
 	private volatile ObservationRegistryConfigurer configurer;
 
 	ObservationRegistryPostProcessor(ObjectProvider<ObservationRegistryCustomizer<?>> observationRegistryCustomizers,
 			ObjectProvider<ObservationPredicate> observationPredicates,
 			ObjectProvider<GlobalObservationConvention<?>> observationConventions,
 			ObjectProvider<ObservationHandler<?>> observationHandlers,
-			ObjectProvider<ObservationHandlerGrouping> observationHandlerGrouping) {
+			ObjectProvider<ObservationHandlerGrouping> observationHandlerGrouping,
+			ObjectProvider<ObservationFilter> observationFilters) {
 		this.observationRegistryCustomizers = observationRegistryCustomizers;
 		this.observationPredicates = observationPredicates;
 		this.observationConventions = observationConventions;
 		this.observationHandlers = observationHandlers;
 		this.observationHandlerGrouping = observationHandlerGrouping;
+		this.observationFilters = observationFilters;
 	}
 
 	@Override
@@ -70,7 +75,7 @@ class ObservationRegistryPostProcessor implements BeanPostProcessor {
 		if (this.configurer == null) {
 			this.configurer = new ObservationRegistryConfigurer(this.observationRegistryCustomizers,
 					this.observationPredicates, this.observationConventions, this.observationHandlers,
-					this.observationHandlerGrouping);
+					this.observationHandlerGrouping, this.observationFilters);
 		}
 		return this.configurer;
 	}

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/observation/ObservationAutoConfigurationTests.java

@@ -28,6 +28,7 @@ import io.micrometer.core.instrument.search.MeterNotFoundException;
 import io.micrometer.observation.GlobalObservationConvention;
 import io.micrometer.observation.Observation;
 import io.micrometer.observation.Observation.Context;
+import io.micrometer.observation.ObservationFilter;
 import io.micrometer.observation.ObservationHandler;
 import io.micrometer.observation.ObservationHandler.AllMatchingCompositeObservationHandler;
 import io.micrometer.observation.ObservationHandler.FirstMatchingCompositeObservationHandler;
@@ -176,6 +177,16 @@ class ObservationAutoConfigurationTests {
 		});
 	}
 
+	@Test
+	void autoConfiguresObservationFilters() {
+		this.contextRunner.withUserConfiguration(ObservationFilters.class).run((context) -> {
+			ObservationRegistry observationRegistry = context.getBean(ObservationRegistry.class);
+			Observation.start("filtered", observationRegistry).stop();
+			MeterRegistry meterRegistry = context.getBean(MeterRegistry.class);
+			assertThat(meterRegistry.get("filtered").tag("filter", "one").timer().count()).isOne();
+		});
+	}
+
 	@Test
 	void autoConfiguresGlobalObservationConventions() {
 		this.contextRunner.withUserConfiguration(CustomGlobalObservationConvention.class).run((context) -> {
@@ -273,6 +284,23 @@ class ObservationAutoConfigurationTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class ObservationFilters {
+
+		@Bean
+		@Order(1)
+		ObservationFilter observationFilterOne() {
+			return (context) -> context.addLowCardinalityKeyValue(KeyValue.of("filter", "one"));
+		}
+
+		@Bean
+		@Order(0)
+		ObservationFilter observationFilterTwo() {
+			return (context) -> context.addLowCardinalityKeyValue(KeyValue.of("filter", "two"));
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class CustomGlobalObservationConvention {