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Available as of Camel 2.7
In From Camel 2.7 we migrated to use slf4j as the : Camel uses the SLF4J logging framework in Camel. This allows us Camel to support MDC logging.
See For more details information about about MDC logging in see the logback manual.
The log kit logging framework in use must support MDC. The following frameworks support MDC, such as:
See the log kit documentation logging framework's documentation for how to configure and it to use MDC.
Enabling MDC Logging in Camel
To enable MDC logging in Camel you can do it as followsusing Java:
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CamelContext context = ...
context.setUseMDCLogging(true);
...
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In XML you enable it using the useMDCLogging attribute as followsTo enable MDC logging using Spring XML set CamelContext's useMDCLogging attribute:
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<camelContext xmlns="http://camel.apache.org/schema/spring" useMDCLogging="true">
...
</camelContext>
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MDC
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Information
Camel provides the following context information available for MDC:
Before Camel 2.
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10:
| Div |
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| class | confluenceTableSmall |
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Key | Description |
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exchangeId
| The exchange id | messageId
| Camel |
|
| Wiki Markup |
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{div:class=confluenceTableSmall}
|| Key || Description ||
| {{exchangeId}} | The exchange id |
| {{messageId}} | *Camel * id |
| {{correlationId}} | The correlation id of the exchange if id | correlationId
| The correlation id of the exchange if it's |
EIP | transactionKey
| The id of the transaction for transacted exchanges. Note the id is not unique, but its the id of the transaction template that marks the transaction boundary for the given transaction. Hence we decided to name the key transactionKey and not transactionID to point out this fact. | routeId
| The id of the route, in which the exchange is currently being routed | breadcrumbId
| Camel 2.8: An unique id used for tracking messages across transports. | camelContextId
| Camel 2.8.3/2.9: |
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From Camel 2.10
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:
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| class | confluenceTableSmall |
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Key | Description |
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camel.exchangeId
| The exchange id | camel.messageId
| The message id | camel.correlationId
| The correlation id of the exchange if it's correlated. For example a sub message from the Splitter EIP | camel.transactionKey
| The id of the transaction for transacted exchanges. Note the id is not unique, but its the id of the transaction template that marks the transaction boundary for the given transaction. Hence we decided to name the key transactionKey and not transactionID to point out this fact. | camel.routeId
| The id of the route, in which the exchange is currently being routed | camel.breadcrumbId
| An unique id used for tracking messages across transports. | camel.contextId
| The camel context id used for tracking the message from different camel context. |
|
| Wiki Markup |
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| {div:class=confluenceTableSmall}
|| Key || Description ||
| {{camel.exchangeId}} | The exchange id |
| {{camel.messageId}} | The message id |
| {{camel.correlationId}} | The correlation id of the exchange if it's correlated. For example a sub message from the [Splitter] EIP |
| {{camel.transactionKey}} | The id of the transaction for transacted exchanges. Note the id is not unique, but its the id of the transaction template that marks the transaction boundary for the given transaction. Hence we decided to name the key {{transactionKey}} and not {{transactionID}} to point out this fact. |
| {{camel.routeId}} | The id of the route, in which the exchange is currently being routed |
| {{camel.breadcrumbId}} | An unique id used for tracking messages across transports. |
| {{camel.contextId}} | The camel context id used for tracking the message from different camel context. |
{div} |
The keys are subject to change as we want to align and leverage MDC across other Apache products such as ActiveMQ, ServiceMix and Karaf.
Example
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Using LOG4J
If you use log4j you can configure MDC in the the log4j.properties file as shown:
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log4j.appender.out.layout.ConversionPattern=%d [%-15.15t] %-5p %-30.30c{1} - %-10.10X{camel.exchangeId} - %-10.10X{camel.routeId} - %m%n
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Camel will log on startup if MDC is enabled or not
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INFO SpringCamelContext - - - MDC logging is enabled on CamelContext: camel-1
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The follow snippet is from an unit test which shows MDC in use. Notice Note that the exchange id and route id is are displayed in their respective separate columns in the log file:
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INFO SpringCamelContext - - - Apache Camel (CamelContext: camel-1) started in 1.228 seconds
INFO foo - 358739-0-2 - route-a - Exchange[ExchangePattern:InOnly, BodyType:String, Body:Hello World]
INFO bar - 358739-0-2 - route-b - Exchange[ExchangePattern:InOnly, BodyType:String, Body:Hello World]
INFO MockEndpoint - - - Asserting: Endpoint[mock://result] is satisfied
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Using breadcrumb
Enabling Breadcrumb Support
From Available as of Camel 2.8:
The breadcrumbId key for MDC logging is only available if useBreadcrumb option =true has been enabled set on the CamelContext (its default enabledis true). When enabled Camel will enrich the Camel Message by adding a header to it with the key breadcrumbId containing the id. Camel will use the the messageId if no existing existing breadcrumbId was found in the message. By storing
As the breadcrumb as id is stored in a header allow us to transport the breadcrumb across transports which supports message body and headers. For example HTTP and JMS and many other transports does that.
If you want to disable breadcrumb you do as follows in Java
it will persist across any transport that supports the use of headers, for example the HTTP and JMS transports.
Disabling Breadcrumb Support
Java DSL:
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CamelContext context = ...
context.setUseBreadcrumb(false);
...
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And in XML DSL:
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<camelContext xmlns="http://camel.apache.org/schema/spring" useBreadcrumb="false">
...
</camelContext>
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