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Chapter 72. Log

Log Component

The log: component logs message exchanges to the underlying logging mechanism.

URI format

log:loggingCategory[?options]
Where loggingCategory is the name of the logging category to use. You can append query options to the URI in the following format, ?option=value&option=value&...
For example, a log endpoint typically specifies the logging level using the level option, as follows: 
log:org.apache.camel.example?level=DEBUG
The default logger logs every exchange (regular logging). But Apache Camel also ships with the Throughput logger, which is used whenever the groupSize option is specified.
Also a log in the DSL
There is also a log directly in the DSL, but it has a different purpose. Its meant for lightweight and human logs. See more details at LogEIP.

Options

Option Default Type Description
level INFO String Logging level to use. Possible values: ERROR, WARN, INFO, DEBUG, TRACE, OFF
marker null String Camel 2.9: An optional Marker name to use.
groupSize null Integer An integer that specifies a group size for throughput logging.
groupInterval null Integer If specified will group message stats by this time interval (in millis)
groupDelay 0 Integer Set the initial delay for stats (in millis)
groupActiveOnly true boolean If true, will hide stats when no new messages have been received for a time interval, if false, show stats regardless of message traffic

Formatting

The log formats the execution of exchanges to log lines. By default, the log uses LogFormatter to format the log output, where LogFormatter has the following options:
Option Default Description
showAll false Quick option for turning all options on (multiline, maxChars has to be manually set if to be used).
showExchangeId false Show the unique exchange ID.
showExchangePattern true Shows the Message Exchange Pattern (or MEP for short).
showProperties false Show the exchange properties.
showHeaders false Show the In message headers.
showBodyType true Show the In body Java type.
showBody true Show the In body.
showOut false If the exchange has an Out message, show the Out message.
showException false Apache Camel 2.0: If the exchange has an exception, show the exception message (no stack trace).
showCaughtException false Apache Camel 2.0: If the exchange has a caught exception, show the exception message (no stack trace). A caught exception is stored as a property on the exchange and for instance a doCatch can catch exceptions. See Try Catch Finally.
showStackTrace false Apache Camel 2.0: Show the stack trace, if an exchange has an exception. Only effective if one of showAll, showException or showCaughtException are enabled.
showFiles false Camel 2.9: Whether Camel should show file bodies or not (eg such as java.io.File).
showFuture false Whether Camel should show java.util.concurrent.Future bodies or not. If enabled Camel could potentially wait until the Future task is done. Will by default not wait.
showStreams false Camel 2.8: Whether Camel should show stream bodies or not (eg such as java.io.InputStream). Beware if you enable this option then you may not be able later to access the message body as the stream have already been read by this logger. To remedy this you will have to use Stream Caching.
multiline false If true, each piece of information is logged on a new line.
maxChars Limits the number of characters logged per line. The default value is 10000 from Camel 2.9 onwards.
Logging stream bodies
For older versions of Camel that do not support the showFiles or showStreams properties above, you can set the following property instead on the CamelContext to log both stream and file bodies: 
 camelContext.getProperties().put(Exchange.LOG_DEBUG_BODY_STREAMS, true);

Regular logger sample

In the route below we log the incoming orders at DEBUG level before the order is processed: 
from("activemq:orders").to("log:com.mycompany.order?level=DEBUG").to("bean:processOrder");
Or using Spring XML to define the route: 
  <route>
    <from uri="activemq:orders"/>
    <to uri="log:com.mycompany.order?level=DEBUG"/>
    <to uri="bean:processOrder"/>
  </route>

Regular logger with formatter sample

In the route below we log the incoming orders at INFO level before the order is processed. 
from("activemq:orders").
    to("log:com.mycompany.order?showAll=true&multiline=true").to("bean:processOrder");

Throughput logger with groupSize sample

In the route below we log the throughput of the incoming orders at DEBUG level grouped by 10 messages. 
from("activemq:orders").
    to("log:com.mycompany.order?level=DEBUG&groupSize=10").to("bean:processOrder");

Throughput logger with groupInterval sample

This route will result in message stats logged every 10s, with an initial 60s delay and stats should be displayed even if there isn't any message traffic. 
from("activemq:orders")
    .to("log:com.mycompany.order?level=DEBUG&groupInterval=10000&groupDelay=60000&groupActiveOnly=false")
    .to("bean:processOrder");
The following will be logged: 
"Received: 1000 new messages, with total 2000 so far. Last group took: 10000 millis which is: 100 messages per second. average: 100"

Full customization of the logging output

Available as of Camel 2.11
With the options outlined in the Formatting section, you can control much of the output of the logger. However, log lines will always follow this structure: 
Exchange[Id:ID-machine-local-50656-1234567901234-1-2, ExchangePattern:InOut, 
Properties:{CamelToEndpoint=log://org.apache.camel.component.log.TEST?showAll=true, 
CamelCreatedTimestamp=Thu Mar 28 00:00:00 WET 2013}, 
Headers:{breadcrumbId=ID-machine-local-50656-1234567901234-1-1}, BodyType:String, Body:Hello World, Out: null]
This format is unsuitable in some cases, perhaps because you need to...
  • ... filter the headers and properties that are printed, to strike a balance between insight and verbosity.
  • ... adjust the log message to whatever you deem most readable.
  • ... tailor log messages for digestion by log mining systems, e.g. Splunk.
  • ... print specific body types differently.
  • ... etc.
Whenever you require absolute customization, you can create a class that implements the ExchangeFormatter interface. Within the format(Exchange) method you have access to the full Exchange, so you can select and extract the precise information you need, format it in a custom manner and return it. The return value will become the final log message.
You can have the Log component pick up your custom ExchangeFormatter in either of two ways:
Explicitly instantiating the LogComponent in your Registry: 
<bean name="log" class="org.apache.camel.component.log.LogComponent">
   <property name="exchangeFormatter" ref="myCustomFormatter" />
</bean>
Convention over configuration:
Simply by registering a bean with the name logFormatter; the Log Component is intelligent enough to pick it up automatically. 
<bean name="logFormatter" class="com.xyz.MyCustomExchangeFormatter" />
NOTE: the ExchangeFormatter gets applied to all Log endpoints within that Camel Context. If you need different ExchangeFormatters for different endpoints, just instantiate the LogComponent as many times as needed, and use the relevant bean name as the endpoint prefix.
From Camel 2.11.2/2.12 onwards when using a custom log formatter, you can specify parameters in the log uri, which gets configured on the custom log formatter. Though when you do that you should define the "logForamtter" as prototype scoped so its not shared if you have different parameters, eg: 
<bean name="logFormatter" class="com.xyz.MyCustomExchangeFormatter" scope="prototype"/>
And then we can have Camel routes using the log uri with different options: 
<to uri="log:foo?param1=foo&aram2=100"/>
...
<to uri="log:bar?param1=bar&aram2=200"/>