Monitoring Camel applications on the Cloud

Amazon CloudWatch

Let's say we want to tract the number of failed exchanges in a Camel route. This metric can be retrieved using the jmx component, which lets you subscribe to an mbean's Notifications. The jmx consumer below will cause a new MonitorBean to be created and deployed to the local mbean server that monitors the "ExchangesFailed" attribute on the "processingRoute" bean. And if that attribute value changes, this consumer will send a new message containing the change - i.e. the number of failures so far. After that all you have to do is set that value as CamelAwsCwMetricValue message header and give it a name with the CamelAwsCwMetricName header. The rest will be handled by the cloudwatch producer.

<camel:route>

<camel:from uri="jmx:platform?objectDomain=org.apache.camel&monitorType=counter&differenceMode=false&key.context=MC-SS071464.local/monitorContext&key.type=routes&key.name=%22processingRoute%22&observedAttribute=ExchangesFailed&initThreshold=1&granularityPeriod=5000&offset=1&format=raw"/>

 

<setHeader headerName="CamelAwsCwMetricName">

<simple>${body.observedAttribute}</simple>

</setHeader>

<setHeader headerName="CamelAwsCwMetricValue">

<simple>${body.derivedGauge}</simple>

</setHeader>

<setHeader headerName="CamelAwsCwMetricUnit">

<constant>Count</constant>

</setHeader>

 

<camel:to uri="aws-cw://www.livephotostream.com/live?accessKey=XXX&secretKey=XXX"/>

</camel:route>

The route above doesn't require any additional code. It will send any changes to the ExchangesFailed attribute to CloudWatch service, and you can see the error count not changing in the CloudWatch graph:


The downside of using jmx consumer to monitor a bean is that you will need to create separate consumer and route for each bean and attribute monitored. Another approach is to have a processor that can access the beans from the JMX server, read all the attributes of interest and send all of them at once again using the cloudwatch component.

<route>

<from uri="timer://jmxMonitoringTimer?fixedRate=true&period=10000"/>

 

<process ref="jmxMetricReader" />

 

<camel:to uri="aws-cw://www.livephotostream.com/context?accessKey=XXX&secretKey=XXX"/>

</route>

In this scenario you will need also a timer to trigger the polling. The cloudwatch producer can generate a metric based on message headers as in the first example, or simply send the metric objects from the message body if present as in the second example. The processor for retrieving data from camel jmx is also straightforward and can be seen in the demo app on my guthub account.

The result from the last route is couple of metrics, all of which sent to CloudWatch every minute. As you can see from the next image the number of exchanges completed successfully is increasing all the time, but with a different rate:
From the other hand, the mean processing time (in millis) is different for each message but in close interval and not growing drastically.

If the new metrics doesn't exist in CloudWatch, it will be created for you, but if you want to set up alarms and trigger automatic actions, you still have to log into amazon console and to it manually. And finally don't forget to check your "cloud bill" after adding all these metrics, they are not for free ;)