Stop applying MeterFilters to auto-configured composite registry

Previously, all MeterFilter beans were applied to all MeterRegistry
beans. As a result, when a composite registry was auto-configured, both
the composite and all of its delegates would have the same MeterFilters
applied. This made it impossible for one of the delegate registries to
have a locally-configured filter that would allow a meter that would be
denied by one of the MeterFilter beans applied to the composite.

This commit update MeterRegistryConfigurer to skips the auto-configured
composite meter registry when applying MeterFilter beans to
MeterRegistry beans. As a result, the composite's filters will no
longer deny a meter before it reaches a delegate that would have
accepted it due to one of its locally-configured filters.

Closes gh-23381

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/AutoConfiguredCompositeMeterRegistry.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2012-2020 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.actuate.autoconfigure.metrics;
+
+import java.util.List;
+
+import io.micrometer.core.instrument.Clock;
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.composite.CompositeMeterRegistry;
+
+/**
+ * Specialization of {@link CompositeMeterRegistry} used to identify the auto-configured
+ * composite.
+ *
+ * @author Andy Wilkinson
+ */
+class AutoConfiguredCompositeMeterRegistry extends CompositeMeterRegistry {
+
+	AutoConfiguredCompositeMeterRegistry(Clock clock, List<MeterRegistry> registries) {
+		super(clock, registries);
+	}
+
+}

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/CompositeMeterRegistryConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -42,8 +42,8 @@ class CompositeMeterRegistryConfiguration {
 
 	@Bean
 	@Primary
-	CompositeMeterRegistry compositeMeterRegistry(Clock clock, List<MeterRegistry> registries) {
-		return new CompositeMeterRegistry(clock, registries);
+	AutoConfiguredCompositeMeterRegistry compositeMeterRegistry(Clock clock, List<MeterRegistry> registries) {
+		return new AutoConfiguredCompositeMeterRegistry(clock, registries);
 	}
 
 	static class MultipleNonPrimaryMeterRegistriesCondition extends NoneNestedConditions {

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/MeterRegistryConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -61,7 +61,9 @@ class MeterRegistryConfigurer {
 		// Customizers must be applied before binders, as they may add custom
 		// tags or alter timer or summary configuration.
 		customize(registry);
-		addFilters(registry);
+		if (!(registry instanceof AutoConfiguredCompositeMeterRegistry)) {
+			addFilters(registry);
+		}
 		if (!this.hasCompositeMeterRegistry || registry instanceof CompositeMeterRegistry) {
 			addBinders(registry);
 		}

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/MetricsAutoConfigurationIntegrationTests.java

@@ -16,6 +16,9 @@
 
 package org.springframework.boot.actuate.autoconfigure.metrics;
 
+import java.util.Arrays;
+import java.util.Set;
+
 import io.micrometer.core.instrument.MeterRegistry;
 import io.micrometer.core.instrument.MockClock;
 import io.micrometer.core.instrument.composite.CompositeMeterRegistry;
@@ -23,6 +26,7 @@ import io.micrometer.core.instrument.simple.SimpleConfig;
 import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
 import io.micrometer.graphite.GraphiteMeterRegistry;
 import io.micrometer.jmx.JmxMeterRegistry;
+import org.assertj.core.api.InstanceOfAssertFactories;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.actuate.autoconfigure.metrics.export.graphite.GraphiteMetricsExportAutoConfiguration;
@@ -109,6 +113,35 @@ class MetricsAutoConfigurationIntegrationTests {
 				});
 	}
 
+	@Test
+	void autoConfiguredCompositeDoesNotHaveMeterFiltersApplied() {
+		new ApplicationContextRunner().with(MetricsRun.limitedTo(GraphiteMetricsExportAutoConfiguration.class,
+				JmxMetricsExportAutoConfiguration.class)).run((context) -> {
+					MeterRegistry composite = context.getBean(MeterRegistry.class);
+					assertThat(composite).extracting("filters", InstanceOfAssertFactories.ARRAY).hasSize(0);
+					assertThat(composite).isInstanceOf(CompositeMeterRegistry.class);
+					Set<MeterRegistry> registries = ((CompositeMeterRegistry) composite).getRegistries();
+					assertThat(registries).hasSize(2);
+					assertThat(registries).hasAtLeastOneElementOfType(GraphiteMeterRegistry.class)
+							.hasAtLeastOneElementOfType(JmxMeterRegistry.class);
+					assertThat(registries).allSatisfy((registry) -> assertThat(registry)
+							.extracting("filters", InstanceOfAssertFactories.ARRAY).hasSize(1));
+				});
+	}
+
+	@Test
+	void userConfiguredCompositeHasMeterFiltersApplied() {
+		new ApplicationContextRunner().with(MetricsRun.limitedTo())
+				.withUserConfiguration(CompositeMeterRegistryConfiguration.class).run((context) -> {
+					MeterRegistry composite = context.getBean(MeterRegistry.class);
+					assertThat(composite).extracting("filters", InstanceOfAssertFactories.ARRAY).hasSize(1);
+					assertThat(composite).isInstanceOf(CompositeMeterRegistry.class);
+					Set<MeterRegistry> registries = ((CompositeMeterRegistry) composite).getRegistries();
+					assertThat(registries).hasSize(2);
+					assertThat(registries).hasOnlyElementsOfTypes(SimpleMeterRegistry.class);
+				});
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class PrimaryMeterRegistryConfiguration {
 
@@ -120,4 +153,17 @@ class MetricsAutoConfigurationIntegrationTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class CompositeMeterRegistryConfiguration {
+
+		@Bean
+		CompositeMeterRegistry compositeMeterRegistry() {
+			CompositeMeterRegistry compositeMeterRegistry = new CompositeMeterRegistry(new MockClock(),
+					Arrays.asList(new SimpleMeterRegistry(), new SimpleMeterRegistry()));
+			System.out.println(compositeMeterRegistry.getRegistries());
+			return compositeMeterRegistry;
+		}
+
+	}
+
 }