Java: How to log raw JSON as JSON and avoid escaping during logging with logback / slf4j

Question

I\'m using SLF4J with Logback in a JAX-RS application... I want to log to JSON in such a way that my message is not encoded again but printed raw into the logfile:

At t

Answer 1

Just came over this myself and found an article with a few recommandations on logging.

If you use maven put this dependency into pom.xml

<dependency>
    <groupId>net.logstash.logback</groupId>
    <artifactId>logstash-logback-encoder</artifactId>
    <version>3.4</version>
</dependency>

And put something like this into logback.xml

<configuration>
    <property name="PROJECT_ID" value="example"/>
    <appender name="file" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <File>logs/${PROJECT_ID}.json</File>
        <encoder class="net.logstash.logback.encoder.LogstashEncoder"/>
        <rollingPolicy class="ch.qos.logback.core.rolling.FixedWindowRollingPolicy">
            <maxIndex>1</maxIndex>
            <FileNamePattern>logs/${PROJECT_ID}.json.%i</FileNamePattern>
        </rollingPolicy>
        <triggeringPolicy class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
            <MaxFileSize>1MB</MaxFileSize>
        </triggeringPolicy>
    </appender>
    <logger name="eu.kielczewski" additivity="false" level="INFO">
        <appender-ref ref="file"/>
    </logger>
    <root level="WARN">
        <appender-ref ref="file"/>
    </root>
</configuration>

This creates example.json file under logs/. The file is rolled once when it reaches 1MB in size.

LOGGER.debug(append("object", someObject), "log message");