What?

This is a Custom Mule logger to replace MuleSoft's out of the box logger to enforce logging standards on mule application logs. This logger builds and logs Java HashMap with the given key-value pairs thus providing a way to generate consistent and structured log messages.

Why?

One of the reasons for developing this custom module is to feed JSON logs to log analyzers like Splunk, ELK etc. When these log analyzers receive structured logs(JSON), It is easy on the log analyzer side to create reports, dashboards etc. Below are the things this Logger can do when compared to out-of-the-box MuleSoft's logger component.

Easy to use for a Mule developer to log necessary and sufficient data.
Log metadata with each log message like application name, version, environment, location info etc.
Log any number of data points within a log message thus enabling log analyzer to have sufficient data to create stunning reports.
Log exceptions.
Log Correlation ID.
Optionally log location info with each log message.
Tracepoints compatibility to measure request, response times and such.

Here is how mule-custom-logger looks like in action.

This will log Java HashMap as shown below.

INFO  2019-07-01 19:10:59,412 [[MuleRuntime].cpuLight.24: [sample].sampleFlow.CPU_LITE @18c7b87e] [event: dccaf190-9c5d-11e9-9fcf-38f9d373e316] com.avio: {ext={additionalKey1=additionalValue1, additionalKey2=additionalValue2}, exception={detail=null, type=null, statusCode=null}, app_name=sample, app_version=1.0.0, log={trace_point=START, payload=null, correlation_id=a86212d5-d5c0-4b78-96cc-863f581a6ac0, message=This is nothing but a sample log message}, location={line_in_file=17, component=avio-core:custom-logger, file_name=sample.xml, root_container=sampleFlow, location=sampleFlow/processors/1}, env=dev, timestamp=2019-07-02T00:10:59.412Z}

With this custom module producing HashMap,

It would be handy in log4j2.xml to take this HashMap and convert to desired formats using log4j2 layouts. There are many out-of-the-box log4j layouts available here. See https://logging.apache.org/log4j/2.x/manual/layouts.html.
Let appenders in log4j2 decide what layout to use to send to it specified destination.

Below is the out-of-the-box log4j2 JSON layout(wrapped in Console appender) to convert the HashMap produced by the custom module to JSON.

<Console name="Console" target="SYSTEM_OUT">
    <JSONLayout objectMessageAsJsonObject="true"/>
</Console>

Dont forget to add this appender to your root or any of your loggers. See below

<AsyncRoot level="INFO">
    <AppenderRef ref="file"/>
    <AppenderRef ref="Console"/>
</AsyncRoot>

There are several attributes provided by this JSONLayout that you can play with. Above log4j layout definition produces the JSON like below.

{
    "app_name": "sample",
    "app_version": "1.0.0",
    "env": "dev",
    "ext": {
        "additionalKey1": "additionalValue1",
        "additionalKey2": "additionalValue2"
    },
    "location": {
        "component": "avio-core:custom-logger",
        "file_name": "sample.xml",
        "line_in_file": "16",
        "location": "sampleFlow/processors/1",
        "root_container": "sampleFlow"
    },
    "log": {
        "category": "com.avio",
        "correlation_id": "33af6200-018b-42af-8ec1-ebdbf29c0505",
        "level": "INFO",
        "message": "This is nothing but a sample log message",
        "tracePoint": "START"
    },
    "thread": "[MuleRuntime].cpuLight.23: [sample].sampleFlow.CPU_LITE @27346628",
    "timestamp": "2019-05-17T15:06:34.592Z"
}

Important: If you are using this kind of approach(HashMap + JSONLayout in log4j2.xml) for any MuleSoft CloudHub projects, and if you want to see JSON logs in CloudHub console, The CloudHub appender provided by MuleSoft defaults to one pattern and it ignores any layout you specify. Most of the log4j2 appenders should accept layouts though.

How?

Using maven dependency

First, clone this repository and run mvn clean install to install this maven project in your local .m2 repository.

When you install this project into your machine's local .m2 repository, You can include this dependency(see below) in your mule projects. When you included this dependency in your project's pom.xml, AVIO's custom logger component automatically shows up in mule project's pallete and using this logger afterwards is just a drag away.

<dependency>
    <groupId>YOUR_GROUP_ID</groupId>
    <artifactId>mule-custom-logger</artifactId>
    <version>1.0.0</version>
    <classifier>mule-plugin</classifier>
</dependency>

Push to anypoint private exchange

Alternatively, you can push this mule custom component to your anypoint organization's private exchange so that all developers inside that organization can use it. Here are the steps,

First, Clone this GitHub repository into your local machine.
Get your Anypoint's organization ID and
- Place it in pom.xml group id tag. <groupId>YOUR_ORG_ID</groupId>.
- Place it in url tag under distribution management tag. See below

<distributionManagement>
	<repository>
		<id>anypoint-exchange</id>
		<name>Corporate Repository</name>
		<url>https://maven.anypoint.mulesoft.com/api/v1/organizations/YOUR_ORG_ID/maven</url>
		<layout>default</layout>
	</repository>
</distributionManagement>

Include exchange credentials in your settings.xml under servers section and with the matching server id with the repository id in pom's distribution management tag.
Run mvn clean deploy to deploy this custom component into your anypoint exchange.
Now, click on "search on exchange" in your mule project pallete, login and install component in your project.

claytonflesher/mule-custom-logger

What?

Why?

How?

Using maven dependency

Push to anypoint private exchange