Chapter 84. Micrometer
Chapter 84. Micrometer Since Camel 2.22 Only producer is supported The Micrometer component allows to collect various metrics directly from Camel routes. Supported metric types are counter , summary , and timer . Micrometer provides simple way to measure the behavior of an application. Configurable reporting backends (via Micrometer registries) enable different integration options for collecting and visualizing statistics. The component also provides a MicrometerRoutePolicyFactory which allows to expose route statistics using Micrometer as well as EventNotifier implementations for counting routes and timing exchanges from their creation to their completion. 84.1. Dependencies Maven users will need to add the following dependency to their pom.xml for this component: <dependency> <groupId>org.apache.camel.springboot</groupId> <artifactId>camel-micrometer</artifactId> </dependency> At the same time update dependencyManagement section with: <dependencyManagement> <dependencies> <dependency> <groupId>com.redhat.camel.springboot.platform</groupId> <artifactId>camel-spring-boot-bom</artifactId> <version>USD{camel-spring-boot-version}</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement> 84.2. URI format 84.3. Configuring Options Camel components are configured on two separate levels: component level endpoint level 84.3.1. Configuring component options The component level is the highest level which holds general and common configurations that are inherited by the endpoints. For example a component may have security settings, credentials for authentication, urls for network connection and so forth. Some components only have a few options, and others may have many. Because components typically have pre configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all. Configuring components can be done with the Component DSL , in a configuration file (application.properties|yaml), or directly with Java code. 84.3.2. Configuring endpoint options Where you find yourself configuring the most is on endpoints, as endpoints often have many options, which allows you to configure what you need the endpoint to do. The options are also categorized into whether the endpoint is used as consumer (from) or as a producer (to), or used for both. Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL and DataFormat DSL as a type safe way of configuring endpoints and data formats in Java. A good practice when configuring options is to use Property Placeholders , which allows to not hardcode urls, port numbers, sensitive information, and other settings. In other words placeholders allows to externalize the configuration from your code, and gives more flexibility and reuse. The following two sections lists all the options, firstly for the component followed by the endpoint. 84.4. Component Options The Micrometer component supports 3 options, which are listed below. Name Description Default Type lazyStartProducer (producer) Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel's routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. False Boolean autowiredEnabled (advanced) Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc. True Boolean metricsRegistry (advanced) To use a custom configured MetricRegistry. MeterRegistry 84.5. Endpoint Options The Micrometer endpoint is configured using URI syntax: with the following path and query parameters: 84.5.1. Path Parameters (3 parameters) Name Description Default Type metricsType (producer) Required Type of metrics. Enum values: counter summary timer Type metricsName (producer) Required Name of metrics. String tags (producer) Tags of metrics. Iterable 84.5.2. Query Parameters (6 parameters) Name Description Default Type action (producer) Action expression when using timer type. Enum values: start stop String decrement (producer) Decrement value expression when using counter type. String increment (producer) Increment value expression when using counter type. boolean metricsDescription (producer) Description of metrics. String value (producer) Value expression when using histogram type. String lazyStartProducer (producer (advanced)) Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel's routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. False Boolean 84.6. Message Headers The Micrometer component supports 7 message header(s), which is/are listed below: Name Description Default Type CamelMetricsTimerAction (producer) Constant: HEADER_TIMER_ACTION Override timer action in URI. Enum values: start stop MicrometerTimerAction CamelMetricsHistogramValue (producer) Constant: HEADER_HISTOGRAM_VALUE Override histogram value in URI. Long CamelMetricsCounterDecrement (producer) Constant: HEADER_COUNTER_DECREMENT Override decrement value in URI. Double CamelMetricsCounterIncrement (producer) Constant: HEADER_COUNTER_INCREMENT Override increment value in URI. Double CamelMetricsName (producer) Constant: HEADER_METRIC_NAME Override name value in URI. String CamelMetricsDescription (producer) Constant: HEADER_METRIC_DESCRIPTION Override description value in URI. String CamelMetricsTags (producer) Constant: HEADER_METRIC_TAGS To augment meter tags defined as URI parameters. Iterable 84.7. Meter Registry By default the Camel Micrometer component creates a SimpleMeterRegistry instance, suitable mainly for testing. You should define a dedicated registry by providing a MeterRegistry bean. Micrometer registries primarily determine the backend monitoring system to be used. A CompositeMeterRegistry can be used to address more than one monitoring target. For example using Spring Java Configuration: @Configuration public static class MyConfig extends SingleRouteCamelConfiguration { @Bean @Override public RouteBuilder route() { return new RouteBuilder() { @Override public void configure() throws Exception { // define Camel routes here } }; } @Bean(name = MicrometerConstants.METRICS_REGISTRY_NAME) public MeterRegistry getMeterRegistry() { CompositeMeterRegistry registry = ...; registry.add(...); // ... return registry; } } Or using CDI: @Override public void configure() { from("...") // Register the 'my-meter' meter in the MetricRegistry below .to("micrometer:meter:my-meter"); } @Produces // If multiple MetricRegistry beans // @Named(MicrometerConstants.METRICS_REGISTRY_NAME) MetricRegistry registry() { CompositeMeterRegistry registry = ...; registry.add(...); // ... return registry; } } 84.8. Default Camel Metrics Some Camel specific metrics are available out of the box. Name Type Description camel.message.history Timer Sample of performance of each node in the route when message history is enabled camel.routes.added Gauge Number of routes added camel.routes.running Gauge Number of routes running camel.exchanges.inflight Gauge Route inflight messages camel.exchanges.total Counter Total number of processed exchanges camel.exchanges.succeeded Counter Number of successfully completed exchange camel.exchanges.failed Counter Number of failed exchanges camel.exchanges.failures.handled Counter Number of failures handled camel.exchanges.external.redeliveries Counter Number of external initiated redeliveries (such as from JMS broker) camel.exchange.event.notifier Gauge + Summary Metrics for message created, sent, completed, and failed events camel.route.policy Gauge + Summary Route performance metrics camel.route.policy.long.task Gauge + Summary Route long task metric 84.9. Usage of producers Each meter has type and name. Supported types are counter , distribution summary and timer. If no type is provided then a counter is used by default. The meter name is a string that is evaluated as Simple expression. In addition to using the CamelMetricsName header (see below), this allows to select the meter depending on exchange data. The optional tags URI parameter is a comma-separated string, consisting of key=value expressions. Both key and value are strings that are also evaluated as Simple expression. E.g. the URI parameter tags=X=USD{header.Y} would assign the current value of header Y to the key X . 84.9.1. Headers The meter name defined in URI can be overridden by populating a header with name CamelMetricsName. The meter tags defined as URI parameters can be augmented by populating a header with name CamelMetricsTags. For example: from("direct:in") .setHeader(MicrometerConstants.HEADER_METRIC_NAME, constant("new.name")) .setHeader(MicrometerConstants.HEADER_METRIC_TAGS, constant(Tags.of("dynamic-key", "dynamic-value"))) .to("micrometer:counter:name.not.used?tags=key=value") .to("direct:out"); will update a counter with name new.name instead of name.not.used using the tag dynamic-key with value dynamic-value in addition to the tag key with value value . All Metrics specific headers are removed from the message once the Micrometer endpoint finishes processing of exchange. While processing exchange Micrometer endpoint will catch all exceptions and write log entry using level warn . 84.10. Counter micrometer:counter:name[?options] 84.10.1. Options Name Default Description increment Double value to add to the counter decrement Double value to subtract from the counter If neither increment or decrement is defined then counter value will be incremented by one. If increment and decrement are both defined only increment operation is called. // update counter simple.counter by 7 from("direct:in") .to("micrometer:counter:simple.counter?increment=7") .to("direct:out"); // increment counter simple.counter by 1 from("direct:in") .to("micrometer:counter:simple.counter") .to("direct:out"); Both increment and decrement values are evaluated as Simple expressions with a Double result, e.g. if header X contains a value that evaluates to 3.0, the simple.counter counter is decremented by 3.0: // decrement counter simple.counter by 3 from("direct:in") .to("micrometer:counter:simple.counter?decrement=USD{header.X}") .to("direct:out"); 84.10.2. Headers Like in camel-metrics, specific Message headers can be used to override increment and decrement values specified in the Micrometer endpoint URI. Name Description Expected type CamelMetricsCounterIncrement Double value to add to the counter CamelMetricsCounterDecrement Double value to subtract from the counter from("direct:in") .setHeader(MicrometerConstants.HEADER_COUNTER_INCREMENT, constant(417.0D)) .to("micrometer:counter:simple.counter?increment=7") .to("direct:out"); from("direct:in") .setHeader(MicrometerConstants.HEADER_COUNTER_INCREMENT, simple("USD{body.length}")) .to("micrometer:counter:body.length") .to("direct:out"); 84.11. Distribution Summary micrometer:summary:metricname[?options] 84.11.1. Options Name Default Description value Value to use in histogram If no value is not set, nothing is added to histogram and warning is logged. // adds value 9923 to simple.histogram from("direct:in") .to("micrometer:summary:simple.histogram?value=9923") .to("direct:out"); // nothing is added to simple.histogram; warning is logged from("direct:in") .to("micrometer:summary:simple.histogram") .to("direct:out"); value is evaluated as Simple expressions with a Double result, e.g. if header X contains a value that evaluates to 3.0, this value is registered with the simple.histogram : from("direct:in") .to("micrometer:summary:simple.histogram?value=USD{header.X}") .to("direct:out"); 84.11.2. Headers Like in camel-metrics , a specific Message header can be used to override the value specified in the Micrometer endpoint URI. Name Description Expected type CamelMetricsHistogramValue Override histogram value in URI Long // adds value 992.0 to simple.histogram from("direct:in") .setHeader(MicrometerConstants.HEADER_HISTOGRAM_VALUE, constant(992.0D)) .to("micrometer:summary:simple.histogram?value=700") .to("direct:out") 84.12. Timer micrometer:timer:metricname[?options] 84.12.1. Options Name Default Description action start or stop If no action or invalid value is provided then warning is logged without any timer update. If action start is called on an already running timer or stop is called on an unknown timer, nothing is updated and warning is logged. // measure time spent in route "direct:calculate" from("direct:in") .to("micrometer:timer:simple.timer?action=start") .to("direct:calculate") .to("micrometer:timer:simple.timer?action=stop"); Timer.Sample objects are stored as Exchange properties between different Metrics component calls. action is evaluated as a Simple expression returning a result of type MicrometerTimerAction . 84.12.2. Headers Like in camel-metrics , a specific Message header can be used to override action value specified in the Micrometer endpoint URI. Name Description Expected type CamelMetricsTimerAction Override timer action in URI org.apache.camel.component.micrometer.MicrometerTimerAction // sets timer action using header from("direct:in") .setHeader(MicrometerConstants.HEADER_TIMER_ACTION, MicrometerTimerAction.start) .to("micrometer:timer:simple.timer") .to("direct:out"); 84.13. Using Micrometer route policy factory MicrometerRoutePolicyFactory allows to add a RoutePolicy for each route in order to exposes route utilization statistics using Micrometer. This factory can be used in Java and XML as the examples below demonstrates. Note Instead of using the MicrometerRoutePolicyFactory you can define a dedicated MicrometerRoutePolicy per route you want to instrument, in case you only want to instrument a few selected routes. From Java you just add the factory to the CamelContext as shown below: context.addRoutePolicyFactory(new MicrometerRoutePolicyFactory()); And from XML DSL you define a <bean> as follows: <!-- use camel-micrometer route policy to gather metrics for all routes --> <bean id="metricsRoutePolicyFactory" class="org.apache.camel.component.micrometer.routepolicy.MicrometerRoutePolicyFactory"/> The MicrometerRoutePolicyFactory and MicrometerRoutePolicy supports the following options: Name Default Description prettyPrint false Whether to use pretty print when outputting statistics in json format meterRegistry Allow to use a shared MeterRegistry . If none is provided then Camel will create a shared instance used by the this CamelContext. durationUnit TimeUnit.MILLISECONDS The unit to use for duration in when dumping the statistics as json. configuration see below MicrometerRoutePolicyConfiguration.class The MicrometerRoutePolicyConfiguration supports the following options: Name Default Description additionalCounters true activates all additional counters exchangesSucceeded true activates counter for succeeded exchanges exchangesFailed true activates counter for failed exchanges exchangesTotal true activates counter for total count of exchanges externalRedeliveries true activates counter for redeliveries of exchanges failuresHandled true activates counter for handled failures longTask false activates long task timer (current processing time for micrometer) timerInitiator null Consumer<Timer.Builder> for custom initialize Timer longTaskInitiator null Consumer<LongTaskTimer.Builder> for custom initialize LongTaskTimer If JMX is enabled in the CamelContext, the MBean is registered in the type=services tree with name=MicrometerRoutePolicy . 84.14. Using Micrometer message history factory MicrometerMessageHistoryFactory allows to use metrics to capture Message History performance statistics while routing messages. It works by using a Micrometer Timer for each node in all the routes. This factory can be used in Java and XML as the examples below demonstrates. From Java you just set the factory to the CamelContext as shown below: context.setMessageHistoryFactory(new MicrometerMessageHistoryFactory()); And from XML DSL you define a <bean> as follows: <!-- use camel-micrometer message history to gather metrics for all messages being routed --> <bean id="metricsMessageHistoryFactory" class="org.apache.camel.component.micrometer.messagehistory.MicrometerMessageHistoryFactory"/> The following options is supported on the factory: Name Default Description prettyPrint false Whether to use pretty print when outputting statistics in json format meterRegistry Allow to use a shared MeterRegistry . If none is provided then Camel will create a shared instance used by the this CamelContext. durationUnit TimeUnit.MILLISECONDS The unit to use for duration in when dumping the statistics as json. At runtime the metrics can be accessed from Java API or JMX which allows to gather the data as json output. From Java code you can get the service from the CamelContext as shown: MicrometerMessageHistoryService service = context.hasService(MicrometerMessageHistoryService.class); String json = service.dumpStatisticsAsJson(); If JMX is enabled in the CamelContext, the MBean is registered in the type=services tree with name=MicrometerMessageHistory . 84.15. Micrometer event notification There is a MicrometerRouteEventNotifier (counting added and running routes) and a MicrometerExchangeEventNotifier (timing exchanges from their creation to their completion). EventNotifiers can be added to the CamelContext, e.g.: camelContext.getManagementStrategy().addEventNotifier(new MicrometerExchangeEventNotifier()) At runtime the metrics can be accessed from Java API or JMX which allows to gather the data as json output. From Java code you can do get the service from the CamelContext as shown: MicrometerEventNotifierService service = context.hasService(MicrometerEventNotifierService.class); String json = service.dumpStatisticsAsJson(); If JMX is enabled in the CamelContext, the MBean is registered in the type=services tree with name=MicrometerEventNotifier . 84.16. Instrumenting Camel Thread Pools InstrumentedThreadPoolFactory allows you to gather performance information about Camel Thread Pools by injecting a InstrumentedThreadPoolFactory which collects information from inside of Camel. See more details at Advanced configuration of CamelContext using Spring. 84.17. Exposing Micrometer statistics in JMX Micrometer uses MeterRegistry implementations in order to publish statistics. While in production scenarios it is advisable to select a dedicated backend like Prometheus or Graphite, it may be sufficient for test or local deployments to publish statistics to JMX. In order to achieve this, add the following dependency: <dependency> <groupId>io.micrometer</groupId> <artifactId>micrometer-registry-jmx</artifactId> <version>USD{micrometer-version}</version> </dependency> and add a JmxMeterRegistry instance: @Bean(name = MicrometerConstants.METRICS_REGISTRY_NAME) public MeterRegistry getMeterRegistry() { CompositeMeterRegistry meterRegistry = new CompositeMeterRegistry(); meterRegistry.add(...); meterRegistry.add(new JmxMeterRegistry( CamelJmxConfig.DEFAULT, Clock.SYSTEM, HierarchicalNameMapper.DEFAULT)); return meterRegistry; } } The HierarchicalNameMapper strategy determines how meter name and tags are assembled into an MBean name. 84.18. Using Camel Micrometer with Spring Boot When you use camel-micrometer-starter with Spring Boot, then Spring Boot auto configuration will automatically enable metrics capture if a io.micrometer.core.instrument.MeterRegistry is available. For example to capture data with Prometheus, you can add the following dependency: <dependency> <groupId>io.micrometer</groupId> <artifactId>micrometer-registry-prometheus</artifactId> </dependency> See the following table for options to specify what metrics to capture, or to turn it off. 84.19. Spring Boot Auto Configuration Compared to the plain camel micrometer, micrometer component on Spring Boot provides 10 more options, which are listed below: Name Description Default Type camel.component.micrometer.autowired-enabled Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc. True Boolean camel.component.micrometer.enabled Whether to enable auto configuration of the micrometer component. This is enabled by default. Boolean camel.component.micrometer.lazy-start-producer Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel's routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. False Boolean camel.component.micrometer.metrics-registry To use a custom configured MetricRegistry. The option is a io.micrometer.core.instrument.MeterRegistry type. MeterRegistry camel.metrics.enable-exchange-event-notifier Set whether to enable the MicrometerExchangeEventNotifier for capturing metrics on exchange processing times. True Boolean camel.metrics.enable-message-history Set whether to enable the MicrometerMessageHistoryFactory for capturing metrics on individual route node processing times. Depending on the number of configured route nodes, there is the potential to create a large volume of metrics. Therefore, this option is disabled by default. False Boolean camel.metrics.enable-route-event-notifier Set whether to enable the MicrometerRouteEventNotifier for capturing metrics on the total number of routes and total number of routes running. True Boolean camel.metrics.enable-route-policy Set whether to enable the MicrometerRoutePolicyFactory for capturing metrics on route processing times. True Boolean camel.metrics.uri-tag-dynamic Whether to use static or dynamic values for URI tags in captured metrics. When using dynamic tags, then a REST service with base URL: /users/{id} will capture metrics with uri tag with the actual dynamic value such as: /users/123. However, this can lead to many tags as the URI is dynamic, so use this with care. False Boolean camel.metrics.uri-tag-enabled Whether HTTP uri tags should be enabled or not in captured metrics. If disabled then the uri tag, is likely not able to be resolved and will be marked as UNKNOWN. True Boolean
<dependency> <groupId>org.apache.camel.springboot</groupId> <artifactId>camel-micrometer</artifactId> </dependency> <dependencyManagement> <dependencies> <dependency> <groupId>com.redhat.camel.springboot.platform</groupId> <artifactId>camel-spring-boot-bom</artifactId> <version>USD{camel-spring-boot-version}</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement> micrometer:[ counter | summary | timer ]:metricname[?options] micrometer:metricsType:metricsName @Configuration public static class MyConfig extends SingleRouteCamelConfiguration { @Bean @Override public RouteBuilder route() { return new RouteBuilder() { @Override public void configure() throws Exception { // define Camel routes here } }; } @Bean(name = MicrometerConstants.METRICS_REGISTRY_NAME) public MeterRegistry getMeterRegistry() { CompositeMeterRegistry registry = ...; registry.add(...); // return registry; } } @Override public void configure() { from("...") // Register the 'my-meter' meter in the MetricRegistry below .to("micrometer:meter:my-meter"); } @Produces // If multiple MetricRegistry beans // @Named(MicrometerConstants.METRICS_REGISTRY_NAME) MetricRegistry registry() { CompositeMeterRegistry registry = ...; registry.add(...); // return registry; } } from("direct:in") .setHeader(MicrometerConstants.HEADER_METRIC_NAME, constant("new.name")) .setHeader(MicrometerConstants.HEADER_METRIC_TAGS, constant(Tags.of("dynamic-key", "dynamic-value"))) .to("micrometer:counter:name.not.used?tags=key=value") .to("direct:out"); micrometer:counter:name[?options] // update counter simple.counter by 7 from("direct:in") .to("micrometer:counter:simple.counter?increment=7") .to("direct:out"); // increment counter simple.counter by 1 from("direct:in") .to("micrometer:counter:simple.counter") .to("direct:out"); // decrement counter simple.counter by 3 from("direct:in") .to("micrometer:counter:simple.counter?decrement=USD{header.X}") .to("direct:out"); from("direct:in") .setHeader(MicrometerConstants.HEADER_COUNTER_INCREMENT, constant(417.0D)) .to("micrometer:counter:simple.counter?increment=7") .to("direct:out"); from("direct:in") .setHeader(MicrometerConstants.HEADER_COUNTER_INCREMENT, simple("USD{body.length}")) .to("micrometer:counter:body.length") .to("direct:out"); micrometer:summary:metricname[?options] // adds value 9923 to simple.histogram from("direct:in") .to("micrometer:summary:simple.histogram?value=9923") .to("direct:out"); // nothing is added to simple.histogram; warning is logged from("direct:in") .to("micrometer:summary:simple.histogram") .to("direct:out"); from("direct:in") .to("micrometer:summary:simple.histogram?value=USD{header.X}") .to("direct:out"); // adds value 992.0 to simple.histogram from("direct:in") .setHeader(MicrometerConstants.HEADER_HISTOGRAM_VALUE, constant(992.0D)) .to("micrometer:summary:simple.histogram?value=700") .to("direct:out") micrometer:timer:metricname[?options] // measure time spent in route "direct:calculate" from("direct:in") .to("micrometer:timer:simple.timer?action=start") .to("direct:calculate") .to("micrometer:timer:simple.timer?action=stop"); // sets timer action using header from("direct:in") .setHeader(MicrometerConstants.HEADER_TIMER_ACTION, MicrometerTimerAction.start) .to("micrometer:timer:simple.timer") .to("direct:out"); context.addRoutePolicyFactory(new MicrometerRoutePolicyFactory()); <!-- use camel-micrometer route policy to gather metrics for all routes --> <bean id="metricsRoutePolicyFactory" class="org.apache.camel.component.micrometer.routepolicy.MicrometerRoutePolicyFactory"/> context.setMessageHistoryFactory(new MicrometerMessageHistoryFactory()); <!-- use camel-micrometer message history to gather metrics for all messages being routed --> <bean id="metricsMessageHistoryFactory" class="org.apache.camel.component.micrometer.messagehistory.MicrometerMessageHistoryFactory"/> MicrometerMessageHistoryService service = context.hasService(MicrometerMessageHistoryService.class); String json = service.dumpStatisticsAsJson(); camelContext.getManagementStrategy().addEventNotifier(new MicrometerExchangeEventNotifier()) MicrometerEventNotifierService service = context.hasService(MicrometerEventNotifierService.class); String json = service.dumpStatisticsAsJson(); <dependency> <groupId>io.micrometer</groupId> <artifactId>micrometer-registry-jmx</artifactId> <version>USD{micrometer-version}</version> </dependency> @Bean(name = MicrometerConstants.METRICS_REGISTRY_NAME) public MeterRegistry getMeterRegistry() { CompositeMeterRegistry meterRegistry = new CompositeMeterRegistry(); meterRegistry.add(...); meterRegistry.add(new JmxMeterRegistry( CamelJmxConfig.DEFAULT, Clock.SYSTEM, HierarchicalNameMapper.DEFAULT)); return meterRegistry; } } <dependency> <groupId>io.micrometer</groupId> <artifactId>micrometer-registry-prometheus</artifactId> </dependency>