Fix default HierarchicalNameMapper implementation for Graphite

Closes gh-12557

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/export/graphite/GraphiteMetricsExportAutoConfiguration.java

@@ -19,6 +19,7 @@ package org.springframework.boot.actuate.autoconfigure.metrics.export.graphite;
 import io.micrometer.core.instrument.Clock;
 import io.micrometer.core.instrument.util.HierarchicalNameMapper;
 import io.micrometer.graphite.GraphiteConfig;
+import io.micrometer.graphite.GraphiteHierarchicalNameMapper;
 import io.micrometer.graphite.GraphiteMeterRegistry;
 
 import org.springframework.boot.actuate.autoconfigure.metrics.CompositeMeterRegistryAutoConfiguration;
@@ -66,8 +67,8 @@ public class GraphiteMetricsExportAutoConfiguration {
 
 	@Bean
 	@ConditionalOnMissingBean
-	public HierarchicalNameMapper hierarchicalNameMapper() {
-		return HierarchicalNameMapper.DEFAULT;
+	public HierarchicalNameMapper hierarchicalNameMapper(GraphiteConfig graphiteConfig) {
+		return new GraphiteHierarchicalNameMapper(graphiteConfig.tagsAsPrefix());
 	}
 
 }

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/export/graphite/GraphiteMetricsExportAutoConfigurationTests.java

@@ -19,6 +19,7 @@ package org.springframework.boot.actuate.autoconfigure.metrics.export.graphite;
 import java.util.Map;
 
 import io.micrometer.core.instrument.Clock;
+import io.micrometer.core.instrument.Tags;
 import io.micrometer.graphite.GraphiteConfig;
 import io.micrometer.graphite.GraphiteMeterRegistry;
 import org.junit.Test;
@@ -39,6 +40,7 @@ import static org.mockito.Mockito.verify;
  * Tests for {@link GraphiteMetricsExportAutoConfiguration}.
  *
  * @author Andy Wilkinson
+ * @author Stephane Nicoll
  */
 public class GraphiteMetricsExportAutoConfigurationTests {
 
@@ -52,6 +54,20 @@ public class GraphiteMetricsExportAutoConfigurationTests {
 				.doesNotHaveBean(GraphiteMeterRegistry.class));
 	}
 
+	@Test
+	public void autoConfiguresUseTagsAsPrefix() {
+		this.contextRunner.withUserConfiguration(BaseConfiguration.class)
+				.withPropertyValues("management.metrics.export.graphite.tags-as-prefix=app")
+				.run((context) -> {
+					assertThat(context).hasSingleBean(GraphiteMeterRegistry.class);
+					GraphiteMeterRegistry registry = context.getBean(
+							GraphiteMeterRegistry.class);
+					registry.counter("test.count", Tags.of("app", "myapp"));
+					assertThat(registry.getDropwizardRegistry().getMeters())
+							.containsOnlyKeys("myapp.testCount");
+				});
+	}
+
 	@Test
 	public void autoConfiguresItsConfigAndMeterRegistry() {
 		this.contextRunner.withUserConfiguration(BaseConfiguration.class)