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Log Settings in Spring Boot

Logging is an essential aspect of any application development process. It helps developers to monitor and troubleshoot their applications effectively. Spring Boot provides a robust logging framework that allows developers to configure and customize their application logs easily. In this blog post, we will explore the various log settings in Spring Boot and how to configure them.

Logging Frameworks in Spring Boot

Spring Boot supports several logging frameworks, including Logback, Log4j2, and JDK Logging. By default, Spring Boot uses Logback as its logging framework. However, you can switch to other logging frameworks by adding the necessary dependencies to your project.

Logging Levels

Logging levels determine the severity of a log message. Spring Boot supports several logging levels, including TRACE, DEBUG, INFO, WARN, and ERROR. By default, Spring Boot logs messages with a level of INFO or higher. You can configure the logging level for your application by setting the logging.level property in your application.properties or application.yml file.

logging:
  level:
    com.example: DEBUG

In the example above, we have set the logging level for the com.example package to DEBUG. This means that all log messages from the com.example package and its sub-packages with a level of DEBUG or higher will be logged.

Logging Output

Spring Boot supports several logging output formats, including console, file, and syslog. By default, Spring Boot logs messages to the console. However, you can configure the logging output by setting the logging.file or logging.path property in your application.properties or application.yml file.

logging:
  file: /var/log/myapp.log

In the example above, we have set the logging output to a file named myapp.log in the /var/log directory.

Customizing Logback Configuration

Logback is the default logging framework in Spring Boot. You can customize the Logback configuration by creating a logback-spring.xml or logback.xml file in the src/main/resources directory of your project. In this file, you can define your logging appenders, loggers, and log levels.

<configuration>
  <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
    <encoder>
      <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
    </encoder>
  </appender>

  <logger name="com.example" level="DEBUG"/>

  <root level="INFO">
    <appender-ref ref="CONSOLE"/>
  </root>
</configuration>

In the example above, we have defined a console appender that logs messages with a specific pattern. We have also set the logging level for the com.example package to DEBUG.

Conclusion

In this blog post, we have explored the various log settings in Spring Boot and how to configure them. We have seen how to set the logging level, output, and customize the Logback configuration. By configuring your application logs correctly, you can monitor and troubleshoot your application effectively.