Logging (Spring Boot)

Logback JSON structured logging

Eg: fpdefense

Each log line will be a JSON object with fields like @timestamp, @version, message, logger_name, thread_name, level, and stack traces as structured arrays. If you need to customize which fields appear or add MDC context, the LogstashEncoder supports extensive configuration via nested elements in the appender.

pom.xml

    <!-- Logback JSON encoder (structured logging) -->

    <dependency>

      <groupId>net.logstash.logback</groupId>

      <artifactId>logstash-logback-encoder</artifactId>

      <version>9.0</version>

    </dependency>

src/main/resources/logback-spring.xml

Easy to read for humans (profile local) and structured log for tools (profile !local)

<?xml version="1.0" encoding="UTF-8"?>

<configuration xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

  <!-- Appender for development -->

  <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">

    <encoder>

      <pattern>%gray(%d{yyyy-MM-dd HH:mm:ss:SSS}) %highlight(%-5level) %cyan(%C{1}.%M:%L) - %m%n</pattern>

    </encoder>

  </appender>

  <!-- Appender for CloudWatch -->

  <appender name="CLOUDWATCH_JSON" class="ch.qos.logback.core.ConsoleAppender">

    <encoder class="net.logstash.logback.encoder.LogstashEncoder">

      <includeLevelValue>false</includeLevelValue> 

      <fieldNames>

        <timestamp>@timestamp</timestamp>

        <message>@message</message>

        <logger>logger</logger>

        <level>level</level>

        <levelValue>[ignore]</levelValue>

        <thread>thread</thread>

        <version>[ignore]</version> 

      </fieldNames>

    </encoder>

  </appender>

  <!-- Enable DEBUG (or TRACE) only for tests ·

  <logger name="edu.cou" level="DEBUG"/> -->

  <!-- LOG_HUMAN_READABLE=true: Easy to read by humans (for local development) -->

  <!-- LOG_HUMAN_READABLE unset or false: Structured JSON for CloudWatch -->

  <condition class="ch.qos.logback.core.boolex.PropertyEqualityCondition">

    <key>LOG_HUMAN_READABLE</key>

    <value>true</value>

  </condition>

  <if>

    <then>

      <root level="INFO">

        <appender-ref ref="CONSOLE" />

      </root>

    </then>

    <else>

      <root level="INFO">

        <appender-ref ref="CLOUDWATCH_JSON" />

      </root>

     </else>

  </if>

</configuration>

src/test/resources/logback-spring.xml

Easy to read for humans

<?xml version="1.0" encoding="UTF-8"?>

<configuration xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

  <!-- Appender for development -->

  <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">

    <encoder>

      <pattern>%gray(%d{yyyy-MM-dd HH:mm:ss:SSS}) %highlight(%-5level) %cyan(%C{1}.%M:%L) - %m%n</pattern>

    </encoder>

  </appender>

  <!-- Enable DEBUG (or TRACE) only for tests · -->

  <logger name="edu.cou" level="DEBUG"/>

  <!-- Easy to read by humans -->

  <root level="INFO">

    <appender-ref ref="CONSOLE" />

  </root>

</configuration>

Human readable log selection for development purposes:

Appender selection is based in environment variable LOG_HUMAN_READABLE:

LOG_HUMAN_READABLE=true --> Easy to read by humans

LOG_HUMAN_READABLE unset or false --> Structured JSON

Eg:

export LOG_HUMAN_READABLE=true