<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-metrics</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

metrics:[ meter | counter | histogram | timer ]:metricname[?options]

@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 = MetricsComponent.METRIC_REGISTRY_NAME)
    public MetricRegistry getMetricRegistry() {
        MetricRegistry registry = ...;
        return registry;
    }
}

MetricRegistry uses internal thread(s) for reporting. There is no public API in DropWizard version 3.0.1 for users to clean up on exit. Thus using Camel Metrics Component leads to Java classloader leak and my cause OutOfMemoryErrors in some cases.

from("direct:in")
    .setHeader(MetricsConstants.HEADER_METRIC_NAME, constant("new.name"))
    .to("metrics:counter:name.not.used")
    .to("direct:out");

metrics:counter:metricname[?options]

// update counter simple.counter by 7
from("direct:in")
    .to("metric:counter:simple.counter?increment=7")
    .to("direct:out");

// increment counter simple.counter by 1
from("direct:in")
    .to("metric:counter:simple.counter")
    .to("direct:out");

// decrement counter simple.counter by 3
from("direct:in")
    .to("metric:counter:simple.counter?decrement=3")
    .to("direct:out");

// update counter simple.counter by 417
from("direct:in")
    .setHeader(MetricsConstants.HEADER_COUNTER_INCREMENT, constant(417L))
    .to("metric:counter:simple.counter?increment=7")
    .to("direct:out");

// updates counter using simple language to evaluate body.length
from("direct:in")
    .setHeader(MetricsConstants.HEADER_COUNTER_INCREMENT, simple("${body.length}"))
    .to("metrics:counter:body.length")
    .to("mock:out");

metrics:histogram:metricname[?options]

// adds value 9923 to simple.histogram
from("direct:in")
    .to("metric:histogram:simple.histogram?value=9923")
    .to("direct:out");

// nothing is added to simple.histogram; warning is logged
from("direct:in")
    .to("metric:histogram:simple.histogram")
    .to("direct:out");

// Adds value 992 to simple.histogram
from("direct:in")
    .setHeader(MetricsConstants.HEADER_HISTOGRAM_VALUE, constant(992L))
    .to("metric:histogram:simple.histogram?value=700")
    .to("direct:out")

metrics:meter:metricname[?options]

// marks simple.meter without value
from("direct:in")
    .to("metric:simple.meter")
    .to("direct:out");

// marks simple.meter with value 81
from("direct:in")
    .to("metric:meter:simple.meter?mark=81")
    .to("direct:out");

// updates meter simple.meter with value 345
from("direct:in")
    .setHeader(MetricsConstants.HEADER_METER_MARK, constant(345L))
    .to("metric:meter:simple.meter?mark=123")
    .to("direct:out");

metrics:timer:metricname[?options]

// measure time taken by route "calculate"
from("direct:in")
    .to("metrics:timer:simple.timer?action=start")
    .to("direct:calculate")
    .to("metrics:timer:simple.timer?action=stop");

// sets timer action using header
from("direct:in")
    .setHeader(MetricsConstants.HEADER_TIMER_ACTION, TimerAction.start)
    .to("metric:timer:simple.timer")
    .to("direct:out");

Instead of using the MetricsRoutePolicyFactory you can define a MetricsRoutePolicy per route you want to instrument, in case you only want to instrument a few selected routes.

context.addRoutePolicyFactory(new MetricsRoutePolicyFactory());

  <!-- use camel-metrics route policy to gather metrics for all routes -->
  <bean id="metricsRoutePolicyFactory" class="org.apache.camel.component.metrics.routepolicy.MetricsRoutePolicyFactory"/>

MetricRegistryService registryService = context.hasService(MetricsRegistryService.class);

if (registryService != null) {
  MetricsRegistry registry = registryService.getMetricsRegistry();
  // ...
}

context.setMessageHistoryFactory(new MetricsMessageHistoryFactory());

  <!-- use camel-metrics message history to gather metrics for all messages being routed -->
  <bean id="metricsMessageHistoryFactory" class="org.apache.camel.component.metrics.messagehistory.MetricsMessageHistoryFactory"/>

MetricsMessageHistoryService service = context.hasService(MetricsMessageHistoryService.class);
String json = service.dumpStatisticsAsJson();