How to log in JSON with Logback?

Question

I'm new to SLF4J and Logback and I'm trying to log every request and response of API following this link. Here's the configuration

<configuration>
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%requestURL | status code: %statusCode | bytes: %bytesSent | elapsed time: %elapsedTime | request-log: %magenta(%requestContent) | response-log: %cyan(%responseContent)</pattern>
        </encoder>
    </appender>
    <appender-ref ref="STDOUT"/>
</configuration>

Currently it's printing:

GET /api/request HTTP/1.1 | status code: 200 | bytes: 599 | elapsed time: 2630 | request-log:  | response-log {"key1":"field1","key2":"field2"}

And I want to log something like:

{
    "url": "GET /api/request HTTP/1.1",
    "status": 200,
    "elapsed_time": 2630 ,
    "response": {
        "key1":"value1",
        "key2":"value2"
    }
}

if you are using spring boot here is the best example https://www.mkyong.com/spring-boot/spring-boot-slf4j-logging-example/ — Ganesh Gudghe, Aug 09 '19 at 06:08
Thanks for the replies. As I understand, the examples above are triggering logger by calling the logger methods. In my case, I'm using FilterRegistrationBean, therefore logger should be working automatically on each request. — Bat-Erdene Zorigtbaatar, Aug 09 '19 at 07:02

score 5 · Answer 1 · answered Aug 09 '19 at 06:34

This would work:

<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
    <encoder class="net.logstash.logback.encoder.LogstashEncoder">
        <jsonFactoryDecorator class="JsonLogDecorator"/>
        <fieldNames>
            <timestamp>timeStamp</timestamp>
            <message>message</message>
            <logger>logger</logger>
            <thread>thread</thread>
            <level>level</level>
            <levelValue>[ignore]</levelValue>
            <version>[ignore]</version>
            <stackTrace>stackTrace</stackTrace>
        </fieldNames>
        <includeMdcKeyName>mdcKeyToInclude</includeMdcKeyName>
    </encoder>
</appender>

JsonLogDecorator is custom class that implements JsonFactoryDecorator.

The `JsonLogDecorator` class cannot be found, but otherwise this works well. — Shastick, Jul 15 '21 at 15:33

How to log in JSON with Logback?

1 Answers1

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