Metrics Component

This repo is inactive since 03.07.2014

• Merged source code to https://github.com/laurikimmel/camel/tree/camel-metrics.
• Created pull request apache/camel#210.
• Issue in Apache Jira https://issues.apache.org/jira/browse/CAMEL-7554.

Documentation

Available as of Camel 2.14

The metrics: component allows you to collect various metrics directly from Camel routes. Supported metric types are counter, meter, histogram and timer. Metrics provides simple way to measure behaviour of your application. Configurable reporting backend is enabling different integration options for collecting and visualizing statistics.

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 ]:metricname[?options]

Metric Registry

If MetricRegistry instance for name metricRegistry is not found from Camel registry default one is used. Default MetricRegistry uses Slf4jReporter and 60 second reporting interval. MetricRegistry instance can be configured by adding bean with name metricRegistry to Camel registry. 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;
        }
    }

Usage

Each metric has type and name. Supported types are counter, meter, histogram and timer. 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(MetricsComponent.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]

Where options are

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 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("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")

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(MetricsComponent.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(MetricsComponent.HEADER_COUNTER_INCREMENT, simple("${body.length}"))
    .to("metrics:counter:body.length")
    .to("mock:out");

Metric type histogram

metrics:histogram:metricname[?options]

Where options are

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("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")

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(MetricsComponent.HEADER_HISTOGRAM_VALUE, constant(992L))
    .to("metric:histogram:simple.histogram?value=700")
    .to("direct:out")

Metric type meter

metrics:meter:metricname[?options]

Where options are

Name	Default	Description
mark	-	Long value to use as mark

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

// 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")

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(MetricsComponent.HEADER_METER_MARK, constant(345L))
    .to("metric:meter:simple.meter?mark=123")
    .to("direct:out")

Metrics type timer

metrics:timer:metricname[?options]

Where options are

Name	Default	Description
action	-	start or stop

If no action or invalid value is provided warning is logged and no timer is updated. If action start is called on already running timer or stop is called on not running timer 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");

Timer Context 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.metrics.timer.TimerEndpoint.TimerAction

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