Make JMX metrics domain configurable

Closes gh-13356

Author: snicoll

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

@@ -30,11 +30,24 @@
 @ConfigurationProperties(prefix = "management.metrics.export.jmx")
 public class JmxProperties {
 
+	/**
+	 * Metrics JMX domain name.
+	 */
+	private String domain = "metrics";
+
 	/**
 	 * Step size (i.e. reporting frequency) to use.
 	 */
 	private Duration step = Duration.ofMinutes(1);
 
+	public String getDomain() {
+		return this.domain;
+	}
+
+	public void setDomain(String domain) {
+		this.domain = domain;
+	}
+
 	public Duration getStep() {
 		return this.step;
 	}

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

@@ -26,6 +26,7 @@
  * Adapter to convert {@link JmxProperties} to a {@link JmxConfig}.
  *
  * @author Jon Schneider
+ * @author Stephane Nicoll
  */
 class JmxPropertiesConfigAdapter extends PropertiesConfigAdapter<JmxProperties>
 		implements JmxConfig {
@@ -39,6 +40,11 @@ public String get(String key) {
 		return null;
 	}
 
+	@Override
+	public String domain() {
+		return get(JmxProperties::getDomain, JmxConfig.super::domain);
+	}
+
 	@Override
 	public Duration step() {
 		return get(JmxProperties::getStep, JmxConfig.super::step);

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

@@ -32,6 +32,7 @@ public class JmxPropertiesTests {
 	public void defaultValuesAreConsistent() {
 		JmxProperties properties = new JmxProperties();
 		JmxConfig config = JmxConfig.DEFAULT;
+		assertThat(properties.getDomain()).isEqualTo(config.domain());
 		assertThat(properties.getStep()).isEqualTo(config.step());
 	}
 

spring-boot-project/spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -1375,6 +1375,7 @@ content into your application. Rather, pick only the properties that you need.
 	management.metrics.export.influx.step=1m # Step size (i.e. reporting frequency) to use.
 	management.metrics.export.influx.uri=http://localhost:8086 # URI of the Influx server.
 	management.metrics.export.influx.user-name= # Login user of the Influx server.
+	management.metrics.export.jmx.domain=metrics # Metrics JMX domain name.
 	management.metrics.export.jmx.enabled=true # Whether exporting of metrics to JMX is enabled.
 	management.metrics.export.jmx.step=1m # Step size (i.e. reporting frequency) to use.
 	management.metrics.export.newrelic.account-id= # New Relic account ID.

spring-boot-project/spring-boot-docs/src/main/asciidoc/production-ready-features.adoc

@@ -1470,10 +1470,17 @@ server] to use can be provided using:
 ==== JMX
 Micrometer provides a hierarchical mapping to
 {micrometer-registry-documentation}/jmx[JMX], primarily as a cheap and portable way to
-view metrics locally. Micrometer provides a default `HierarchicalNameMapper` that governs
-how a dimensional meter id is
-{micrometer-registry-documentation}/jmx#_hierarchical_name_mapping[mapped to flat
-hierarchical names].
+view metrics locally.By default, metrics are exported to the `metrics` JMX domain. The
+domain to use can be provided provided using:
+
+[source,properties,indent=0]
+----
+	management.metrics.export.jmx.domain=com.example.app.metrics
+----
+
+Micrometer provides a default `HierarchicalNameMapper` that governs how a dimensional
+meter id is {micrometer-registry-documentation}/jmx#_hierarchical_name_mapping[mapped to
+flat hierarchical names].
 
 TIP: To take control over this behaviour, define your `JmxMeterRegistry` and supply your
 own `HierarchicalNameMapper`. An auto-configured `JmxConfig` and `Clock` beans are