Metrics

Since Camel 2.14

Only producer is supported

The Metrics component allows to collect various metrics directly from Camel routes. Supported metric types are counter, histogram, meter, timer and gauge. Metrics provides simple way to measure behaviour of application. Configurable reporting backend is enabling different integration options for collecting and visualizing statistics. The component also provides a MetricsRoutePolicyFactory which allows to expose route statistics using Dropwizard Metrics, see bottom of page for details.

Maven users will need to add the following dependency to their pom.xml for this component:

<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>

URI format

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

Configuring Options

Camel components are configured on two separate levels:

  • component level

  • endpoint level

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.

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 as a type safe way of configuring endpoints.

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.

Component Options

The Metrics 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.

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

metricRegistry (advanced)

To use a custom configured MetricRegistry.

MetricRegistry

Endpoint Options

The Metrics endpoint is configured using URI syntax:

metrics:metricsType:metricsName

with the following path and query parameters:

Path Parameters (2 parameters)

Name Description Default Type

metricsType (producer)

Required Type of metrics.

Enum values:

  • gauge

  • counter

  • histogram

  • meter

  • timer

MetricsType

metricsName (producer)

Required Name of metrics.

String

Query Parameters (7 parameters)

Name Description Default Type

action (producer)

Action when using timer type.

Enum values:

  • start

  • stop

MetricsTimerAction

decrement (producer)

Decrement value when using counter type.

Long

increment (producer)

Increment value when using counter type.

Long

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.

boolean

mark (producer)

Mark when using meter type.

Long

subject (producer)

Subject value when using gauge type.

Object

value (producer)

Value value when using histogram type.

Long

Metric Registry

Camel Metrics component uses by default a MetricRegistry instance with a Slf4jReporter that has a 60 second reporting interval. This default registry can be replaced with a custom one by providing a MetricRegistry bean. If multiple MetricRegistry beans exist in the application, the one with name metricRegistry is used.

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

Or using CDI:

class MyBean extends RouteBuilder {

    @Override
    public void configure() {
      from("...")
          // Register the 'my-meter' meter in the MetricRegistry below
          .to("metrics:meter:my-meter");
    }

    @Produces
    // If multiple MetricRegistry beans
    // @Named(MetricsComponent.METRIC_REGISTRY_NAME)
    MetricRegistry registry() {
        MetricRegistry registry = new MetricRegistry();
        // ...
        return registry;
    }
}

Usage

Each metric has type and name. Supported types are counter, histogram, meter, timer and gauge. Metric name is simple string. If metric type is not provided then type meter is used by default.

Headers

Metric name defined in URI can be overridden by using header with name CamelMetricsName.

For example

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

will update counter with name new.name instead of name.not.used.

All Metrics specific headers are removed from the message once Metrics endpoint finishes processing of exchange. While processing exchange Metrics endpoint will catch all exceptions and write log entry using level warn.

Metrics type counter

metrics:counter:metricname[?options]

Options

Name Default Description

increment

-

Long value to add to the counter

decrement

-

Long 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("metrics:counter:simple.counter?increment=7")
    .to("direct:out");
// increment counter simple.counter by 1
from("direct:in")
    .to("metrics:counter:simple.counter")
    .to("direct:out");
// decrement counter simple.counter by 3
from("direct:in")
    .to("metrics:counter:simple.counter?decrement=3")
    .to("direct:out");

Headers

Message headers can be used to override increment and decrement values specified in Metrics component URI.

Name Description Expected type

CamelMetricsCounterIncrement

Override increment value in URI

Long

CamelMetricsCounterDecrement

Override decrement value in URI

Long

 
// update counter simple.counter by 417
from("direct:in")
    .setHeader(MetricsConstants.HEADER_COUNTER_INCREMENT, constant(417L))
    .to("metrics: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");

Metric type histogram

metrics:histogram:metricname[?options]

Options

Name Default Description

value

-

Value to use in histogram

If value is not set nothing is added to histogram and warning is logged.

// adds value 9923 to simple.histogram
from("direct:in")
    .to("metrics:histogram:simple.histogram?value=9923")
    .to("direct:out");
// nothing is added to simple.histogram; warning is logged
from("direct:in")
    .to("metrics:histogram:simple.histogram")
    .to("direct:out");

Headers

Message header can be used to override value specified in Metrics component URI.

Name Description Expected type

CamelMetricsHistogramValue

Override histogram value in URI

Long

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

Metric type meter

metrics:meter:metricname[?options]

Options

Name Default Description

mark

-

Long value to use as mark

If mark is not set then meter.mark() is called without argument.

// marks simple.meter without value
from("direct:in")
    .to("metrics:simple.meter")
    .to("direct:out");
// marks simple.meter with value 81
from("direct:in")
    .to("metrics:meter:simple.meter?mark=81")
    .to("direct:out");

Headers

Message header can be used to override mark value specified in Metrics component URI.

Name Description Expected type

CamelMetricsMeterMark

Override mark value in URI

Long

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

Metrics type timer

metrics:timer:metricname[?options]

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 already running timer or stop is called on not running timer then nothing is updated and warning is logged.

// 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");

TimerContext objects are stored as Exchange properties between different Metrics component calls.

Headers

Message header can be used to override action value specified in Metrics component URI.

Name Description Expected type

CamelMetricsTimerAction

Override timer action in URI

org.apache.camel.component.metrics.MetricsTimerAction

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

Metric type gauge

metrics:gauge:metricname[?options]

Options

Name Default Description

subject

-

Any object to be observed by the gauge

If subject is not defined it’s simply ignored, i.e. the gauge is not registered.

// update gauge "simple.gauge" by a bean "mySubjectBean"
from("direct:in")
    .to("metrics:gauge:simple.gauge?subject=#mySubjectBean")
    .to("direct:out");

Headers

Message headers can be used to override subject values specified in Metrics component URI. Note: if CamelMetricsName header is specified, then new gauge is registered in addition to default one specified in a URI.

Name Description Expected type

CamelMetricsGaugeSubject

Override subject value in URI

Object

 
// update gauge simple.gauge by a String literal "myUpdatedSubject"
from("direct:in")
    .setHeader(MetricsConstants.HEADER_GAUGE_SUBJECT, constant("myUpdatedSubject"))
    .to("metrics:counter:simple.gauge?subject=#mySubjectBean")
    .to("direct:out");

MetricsRoutePolicyFactory

This factory allows to add a RoutePolicy for each route which exposes route utilization statistics using Dropwizard metrics. This factory can be used in Java and XML as the examples below demonstrates.

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.

From Java you just add the factory to the CamelContext as shown below:

context.addRoutePolicyFactory(new MetricsRoutePolicyFactory());

And from XML DSL you define a <bean> as follows:

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

The MetricsRoutePolicyFactory and MetricsRoutePolicy supports the following options:

Name Default Description

useJmx

false

Whether to report fine grained statistics to JMX by using the com.codahale.metrics.JmxReporter.
Notice that if JMX is enabled on CamelContext then a MetricsRegistryService mbean is enlisted under the services type in the JMX tree. That mbean has a single operation to output the statistics using json. Setting useJmx to true is only needed if you want fine grained mbeans per statistics type.

jmxDomain

org.apache.camel.metrics

The JMX domain name

prettyPrint

false

Whether to use pretty print when outputting statistics in json format

metricsRegistry

Allow to use a shared com.codahale.metrics.MetricRegistry. If none is provided then Camel will create a shared instance used by the this CamelContext.

rateUnit

TimeUnit.SECONDS

The unit to use for rate in the metrics reporter or when dumping the statistics as json.

durationUnit

TimeUnit.MILLISECONDS

The unit to use for duration in the metrics reporter or when dumping the statistics as json.

namePattern

name.routeId.type

Camel 2.17: The name pattern to use. Uses dot as separators, but you can change that. The values name, routeId, and type will be replaced with actual value. Where name is the name of the CamelContext. routeId is the name of the route. And type is the value of responses.

From Java code you can get hold of the com.codahale.metrics.MetricRegistry from the org.apache.camel.component.metrics.routepolicy.MetricsRegistryService as shown below:

MetricRegistryService registryService = context.hasService(MetricsRegistryService.class);
if (registryService != null) {
  MetricsRegistry registry = registryService.getMetricsRegistry();
  ...
}

MetricsMessageHistoryFactory

This factory allows to use metrics to capture Message History performance statistics while routing messages. It works by using a metrics 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 MetricsMessageHistoryFactory());

And from XML DSL you define a <bean> as follows:

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

The following options is supported on the factory:

Name Default Description

useJmx

false

Whether to report fine grained statistics to JMX by using the com.codahale.metrics.JmxReporter.
Notice that if JMX is enabled on CamelContext then a MetricsRegistryService mbean is enlisted under the services type in the JMX tree. That mbean has a single operation to output the statistics using json. Setting useJmx to true is only needed if you want fine grained mbeans per statistics type.

jmxDomain

org.apache.camel.metrics

The JMX domain name

prettyPrint

false

Whether to use pretty print when outputting statistics in json format

metricsRegistry

Allow to use a shared com.codahale.metrics.MetricRegistry. If none is provided then Camel will create a shared instance used by the this CamelContext.

rateUnit

TimeUnit.SECONDS

The unit to use for rate in the metrics reporter or when dumping the statistics as json.

durationUnit

TimeUnit.MILLISECONDS

The unit to use for duration in the metrics reporter or when dumping the statistics as json.

namePattern

name.routeId.id.type

The name pattern to use. Uses dot as separators, but you can change that. The values name, routeId, type, and id will be replaced with actual value. Where name is the name of the CamelContext. routeId is the name of the route. The id pattern represents the node id. And type is the value of history.

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:

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

And the JMX API the MBean is registered in the type=services tree with name=MetricsMessageHistoryService.

InstrumentedThreadPoolFactory

This factory 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

Spring Boot Auto-Configuration

When using metrics with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

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

The component supports 4 options, which are listed below.

Name Description Default Type

camel.component.metrics.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.metrics.enabled

Whether to enable auto configuration of the metrics component. This is enabled by default.

Boolean

camel.component.metrics.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.metrics.metric-registry

To use a custom configured MetricRegistry. The option is a com.codahale.metrics.MetricRegistry type.

MetricRegistry
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