Apply MeterRegistryCustomizer to composites

Update `MeterRegistryConfigurer` to also apply customizers to
composite meter registries. Prior to this commit composites were
skipped due to the incorrect assumption that did not contain
their own state.

Closes gh-12762

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

@@ -59,9 +59,6 @@ class MeterRegistryConfigurer {
 	}
 
 	void configure(MeterRegistry registry) {
-		if (registry instanceof CompositeMeterRegistry) {
-			return;
-		}
 		// Customizers must be applied before binders, as they may add custom
 		// tags or alter timer or summary configuration.
 		customize(registry);

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

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2012-2018 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
+ *
+ *      http://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 io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.composite.CompositeMeterRegistry;
+import org.junit.Test;
+
+import org.springframework.boot.actuate.autoconfigure.metrics.export.atlas.AtlasMetricsExportAutoConfiguration;
+import org.springframework.boot.actuate.autoconfigure.metrics.export.prometheus.PrometheusMetricsExportAutoConfiguration;
+import org.springframework.boot.actuate.autoconfigure.metrics.test.MetricsRun;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+
+public class MeterRegistryConfigurerIntegrationTests {
+	private ApplicationContextRunner contextRunner = new ApplicationContextRunner()
+			.with(MetricsRun.limitedTo(AtlasMetricsExportAutoConfiguration.class,
+					PrometheusMetricsExportAutoConfiguration.class));
+
+	@Test
+	public void binderMetricsAreSearchableFromTheComposite() {
+		this.contextRunner
+				.run((context) -> {
+					CompositeMeterRegistry composite = context.getBean(CompositeMeterRegistry.class);
+					composite.get("jvm.memory.used").gauge();
+
+					for (MeterRegistry registry : context.getBeansOfType(MeterRegistry.class).values()) {
+						registry.get("jvm.memory.used").gauge();
+					}
+				});
+	}
+}

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

@@ -35,7 +35,6 @@ import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.BDDMockito.given;
 import static org.mockito.Mockito.inOrder;
 import static org.mockito.Mockito.verify;
-import static org.mockito.Mockito.verifyZeroInteractions;
 
 /**
  * Tests for {@link MeterRegistryConfigurer}.
@@ -73,13 +72,13 @@ public class MeterRegistryConfigurerTests {
 	}
 
 	@Test
-	public void configureWhenCompositeShouldSkip() {
-		this.binders.add(this.mockBinder);
+	public void configureWhenCompositeShouldApplyCustomizer() {
 		this.customizers.add(this.mockCustomizer);
 		MeterRegistryConfigurer configurer = new MeterRegistryConfigurer(this.binders,
 				this.filters, this.customizers, false);
-		configurer.configure(new CompositeMeterRegistry());
-		verifyZeroInteractions(this.mockBinder, this.mockCustomizer);
+		CompositeMeterRegistry composite = new CompositeMeterRegistry();
+		configurer.configure(composite);
+		verify(this.mockCustomizer).customize(composite);
 	}
 
 	@Test

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

@@ -16,10 +16,13 @@
 
 package org.springframework.boot.actuate.autoconfigure.metrics;
 
+import io.micrometer.atlas.AtlasMeterRegistry;
 import io.micrometer.core.instrument.MeterRegistry;
-import io.micrometer.core.instrument.MeterRegistry.Config;
+import io.micrometer.prometheus.PrometheusMeterRegistry;
 import org.junit.Test;
 
+import org.springframework.boot.actuate.autoconfigure.metrics.export.atlas.AtlasMetricsExportAutoConfiguration;
+import org.springframework.boot.actuate.autoconfigure.metrics.export.prometheus.PrometheusMetricsExportAutoConfiguration;
 import org.springframework.boot.actuate.autoconfigure.metrics.test.MetricsRun;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.context.annotation.Bean;
@@ -36,7 +39,8 @@ import static org.assertj.core.api.Assertions.assertThat;
 public class MeterRegistryCustomizerTests {
 
 	private ApplicationContextRunner contextRunner = new ApplicationContextRunner()
-			.with(MetricsRun.simple());
+			.with(MetricsRun.limitedTo(AtlasMetricsExportAutoConfiguration.class,
+					PrometheusMetricsExportAutoConfiguration.class));
 
 	@Test
 	public void commonTagsAreAppliedToAutoConfiguredBinders() {
@@ -44,8 +48,7 @@ public class MeterRegistryCustomizerTests {
 				.withUserConfiguration(MeterRegistryCustomizerConfiguration.class)
 				.run((context) -> {
 					MeterRegistry registry = context.getBean(MeterRegistry.class);
-					assertThat(registry.get("jvm.memory.used").tags("region", "us-east-1")
-							.gauge()).isNotNull();
+					registry.get("jvm.memory.used").tags("region", "us-east-1").gauge();
 				});
 	}
 
@@ -55,9 +58,21 @@ public class MeterRegistryCustomizerTests {
 				.withUserConfiguration(MeterRegistryCustomizerConfiguration.class)
 				.run((context) -> {
 					MeterRegistry registry = context.getBean(MeterRegistry.class);
-					assertThat(
-							registry.get("my.thing").tags("region", "us-east-1").gauge())
-									.isNotNull();
+					registry.get("my.thing").tags("region", "us-east-1").gauge();
+				});
+	}
+
+	@Test
+	public void customizersCanBeAppliedToSpecificRegistryTypes() {
+		this.contextRunner
+				.withUserConfiguration(MeterRegistryCustomizerConfiguration.class)
+				.run((context) -> {
+					MeterRegistry prometheus = context.getBean(PrometheusMeterRegistry.class);
+					prometheus.get("jvm.memory.used").tags("job", "myjob").gauge();
+
+					MeterRegistry atlas = context.getBean(AtlasMeterRegistry.class);
+					assertThat(atlas.find("jvm.memory.used").tags("job", "myjob")
+							.gauge()).isNull();
 				});
 	}
 
@@ -66,10 +81,12 @@ public class MeterRegistryCustomizerTests {
 
 		@Bean
 		public MeterRegistryCustomizer<MeterRegistry> commonTags() {
-			return (registry) -> {
-				Config config = registry.config();
-				config.commonTags("region", "us-east-1");
-			};
+			return (registry) -> registry.config().commonTags("region", "us-east-1");
+		}
+
+		@Bean
+		public MeterRegistryCustomizer<PrometheusMeterRegistry> prometehusOnlyCommonTags() {
+			return (registry) -> registry.config().commonTags("job", "myjob");
 		}
 
 		@Bean