What can the Tracing module do in Mule 4?

The tracing module lets you enhance your logs by setting logging variables to the logging context, removing a logging variable from the context, and clearing all logging variables from the event logging context, and it also lets you modify the correlation ID during flow execution.

What's the difference between Remove logging variable and Clear logging variables?

Remove logging variable removes a single named variable, for example removing `requestPath` so it no longer appears in the context, while Clear logging variables removes all of the logging variables that were created during the flow, so afterward there is no `customerId` logging variable either.

Why does the changed correlation ID only appear in some loggers?

When you add With Correlation ID after the payload logger to change the correlation ID, the updated correlation id is visible only for the logger available under the correlation ID, so a payload logger added afterward at the end will not have the updated correlation id.

Where can I find the sample project and the official reference?

The sample Mule application is on GitHub at https://github.com/shyamrajprasad/mulesoft-tracing-module-integration and the official tracing module reference is at https://docs.mulesoft.com/tracing-module/1.0/.

Tracing Module in Mule 4

Q: How do I show the tracing logging variables in my logs?

Use Mapped Diagnostic Context (MDC), which enriches logging with more context for the current Mule event. Open the `log4j.xml` file and replace `[processor: %X{processorPath}; event: %X{correlationId}]` with `[%MDC]` so the logging variables you set, such as `customerId` and `requestPath`, are printed in the logs.

The tracing module enables you to enhance your logs by adding, removing, and clearing all variables from the logging context for a given Mule event. It also enables you to modify the correlation ID during flow execution.

Uses Of Tracing Module

Clear all the logging variables from the event logging context.
Remove a logging variable from the logging context.
Set logging variables to logging context.
Modify the correlation ID during flow execution

Mule Palette listing Tracing module operations: Clear, Remove, Set logging variable, and With CorrelationID

Tracing Module Application

1 - Create Mule application: Go to Anypoint studio and create a mule project with the name mulesoft-tracing-module-integration.

2 - Add Tracing module: In the mule palette view, click on + Add Modules and search for tracing modules. Drag the Tracing module to your modules.

3 - HTTP Listener: Create an HTTP listener with the default configuration and specify the /trace base path.

4 - MDC Logging: Mapped Diagnostic Context (MDC) enriches logging and improves tracking by providing more context or information in the logs for the current Mule event. By default, Mule logs two MDC entries: processor, which shows the location of the current event; and event, which shows the correlation ID of the event. Open the log4j.xml file and replace [processor: %X{processorPath}; event: %X{correlationId}] with [%MDC].

5 - Create set variable logging: Create a set logging variable for customerId and request path as below. In the logger, we will print the payload.

Mule flow with Listener, Set logging variable for customerId and requestPath, then a Logger

<tracing:set-logging-variable doc:name="customerId" doc:id="0222c54e-b2f3-4353-ab95-be72e993501c" variableName="customerId" value="#[payload.customerId]"/>
<tracing:set-logging-variable doc:name="requestPath" doc:id="2bcaa45d-e469-450e-99ad-a422a656ccbb" variableName="requestPath" value='#["$(attributes.method):$(attributes.requestPath)"]'/>

6 - Run application: Run the application and test it out with the below command.

curl --location --request POST 'http://localhost:8081/trace' \
--header 'Content-Type: application/json' \
--data-raw '{
   "orderId": 54810284,
   "customerId": "CUST-12934",
   "items": [
       "P-123",
       "P-452"
   ]
}'

7 - Verify logs: Verify the logs customerId and request path will be printed in the context path logs. The below log will be printed in the file location mentioned in log4j.xml.

INFO  2022-05-08 21:46:29,898 [[MuleRuntime].uber.07: [mulesoft-tracing-module-integration].mulesoft-tracing-module-integrationFlow.CPU_LITE @69de6b8b] [{correlationId=37e4bf90-ceea-11ec-9c4a-f84d89960c47, customerId=ARG-12934, processorPath=mulesoft-tracing-module-integrationFlow/processors/2, requestPath=POST:/trace}] logging variables: {
"orderId": 548102842,
"customerId": "ARG-12934",
"items": [
"CP-123",
"CP-452"
]
}

Note

You will see different logs in the console with processor and event.

8 - Console log4j changes: Open log4j.xml, add Console logging in Appenders tag. Also, add this reference to the AsyncRoot tag.

<?xml version="1.0" encoding="utf-8"?>
<Configuration>
<Appenders>
       <RollingFile name="file" fileName="${sys:mule.home}${sys:file.separator}logs${sys:file.separator}mulesoft-tracing-module-integration.log"
                filePattern="${sys:mule.home}${sys:file.separator}logs${sys:file.separator}mulesoft-tracing-module-integration-%i.log">
       <PatternLayout pattern="%-5p %d [%t] [%MDC] %c: %m%n"/>
           <SizeBasedTriggeringPolicy size="10 MB"/>
           <DefaultRolloverStrategy max="10"/>
       </RollingFile>
      <Console name="Console" target="SYSTEM_OUT">
         <PatternLayout pattern="%-5p %d [%t] [%MDC] %c: %m%n"/>
       </Console>
   </Appenders>
<Loggers>
       <!-- Http Logger shows wire traffic on DEBUG -->
       <!--AsyncLogger name="org.mule.service.http.impl.service.HttpMessageLogger" level="DEBUG"/-->
       <AsyncLogger name="org.mule.service.http" level="WARN"/>
       <AsyncLogger name="org.mule.extension.http" level="WARN"/>
<!-- Mule logger -->
       <AsyncLogger name="org.mule.runtime.core.internal.processor.LoggerMessageProcessor" level="INFO"/>
<AsyncRoot level="INFO">
           <AppenderRef ref="file"/>
           <AppenderRef ref="Console"/>
       </AsyncRoot>
</Loggers>
</Configuration>

9 - Run application: Re-run the Mule application and verify the logger. The same logging will be printed in the console.

10 - Remove logging variable: After the logger, let’s remove one of the logging variables i.e request path. Also after this, remove the logging variable, and add the logger for payload.

<tracing:remove-logging-variable doc:name="requestPath" doc:id="9d960273-39bc-4589-9b1d-8cb775374c9c" variableName="requestPath"/>

Mule flow extended with a Remove logging variable for requestPath followed by another Logger

11 - Run application and verify: Re-run the application, hit the endpoint, and verify the logs, you will see the request path will be removed from the context path. When you will hit the application multiple times, you will see different correlation IDs.

INFO  2022-05-08 22:08:11,518 [[MuleRuntime].uber.09: [mulesoft-tracing-module-integration].mulesoft-tracing-module-integrationFlow.CPU_LITE @11ace7f9] [{correlationId=3fd22371-ceed-11ec-9c4a-f84d89960c47, customerId=ARG-12934, processorPath=mulesoft-tracing-module-integrationFlow/processors/4}] logging without request path: {
   "orderId": 548102842,
   "customerId": "ARG-12934",
   "items": [
       "CP-123",
       "CP-452"
   ]
}

12 - Clear logging variable: After the payload logger, let’s add a clear logging variable, it will remove all the logging variables which were created during the flow.

Mule flow with a Clear logging variables component added before the final Logger

13 - Re-run application and verify: Run the application again and hit the endpoint and verify the logs. There will be no customerId logging variable.

INFO  2022-05-08 22:08:11,520 [[MuleRuntime].uber.09: [mulesoft-tracing-module-integration].mulesoft-tracing-module-integrationFlow.CPU_LITE @11ace7f9] [{correlationId=3fd22371-ceed-11ec-9c4a-f84d89960c47, processorPath=mulesoft-tracing-module-integrationFlow/processors/6}] no logging variable :: {
   "orderId": 548102842,
   "customerId": "ARG-12934",
   "items": [
       "CP-123",
       "CP-452"
   ]
}

14 - With Correlation ID: Let’s add with correlation id after payload logger, and change correlation Id. I have changed the correlation id to append my name. Add the payload logger into this too.

With CorrelationID config setting Correlation id to the expression correlationId ++ "shyam"

15 - Run the application: Re-run the application, hit the URL again, and verify the logs with the correlation logger. This updated correlation id will be visible only for the logger available under the correlation ID.

INFO  2022-05-08 22:20:33,690 [[MuleRuntime].uber.02: [mulesoft-tracing-module-integration].mulesoft-tracing-module-integrationFlow.CPU_LITE @3b8d37c5] [{correlationId=fa14acc0-ceee-11ec-b249-f84d89960c47: shyam, processorPath=mulesoft-tracing-module-integrationFlow/processors/7/processors/0}] with changed correlation id:: {
   "orderId": 548102842,
   "customerId": "ARG-12934",
   "items": [
       "CP-123",
       "CP-452"
   ]
}

16 - Add payload logger: Add payload logger at the last, you can re-run the application and the updated correlation id will not be available to this logger.

INFO  2022-05-08 22:20:33,696 [[MuleRuntime].uber.04: [mulesoft-tracing-module-integration].mulesoft-tracing-module-integrationFlow.CPU_LITE @3b8d37c5] [{correlationId=fa14acc0-ceee-11ec-b249-f84d89960c47, processorPath=mulesoft-tracing-module-integrationFlow/processors/8}] org.mule.runtime.core.internal.processor.LoggerMessageProcessor: {
   "orderId": 548102842,
   "customerId": "ARG-12934",
   "items": [
       "CP-123",
       "CP-452"
   ]
}

GitHub repository

https://github.com/shyamrajprasad/mulesoft-tracing-module-integration

References

https://docs.mulesoft.com/tracing-module/1.0/

Uses Of Tracing Module

Tracing Module Application

GitHub repository

References

FAQs