Dependencies

Enabling the Spring Boot application to use Log4j2

<!-- Exclude Spring Boot's Default Logging -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter</artifactId>
    <exclusions>
        <exclusion>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-logging</artifactId>
        </exclusion>
    </exclusions>
</dependency>

<!-- Add Log4j2 Dependency -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-log4j2</artifactId>
</dependency>

Log4j Configuration

Add to classpath (or into src/main/resources folder) one of the following files:

• log4j2-spring.xml
• log4j2.xml
• log4j2.properties

See Log4j2 for more configurations

Example log4j-spring.xml file

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<?xml version="1.0" encoding="UTF-8"?>
<Configuration>
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout
                pattern="%style{%d{ISO8601}}{black} %highlight{%-5level }[%style{%t}{bright,blue}] %style{%C{1.}}{bright,yellow}: %msg%n%throwable" />
        </Console>

        <RollingFile name="RollingFile"
            fileName="./logs/spring-boot-logger-log4j2.log"
            filePattern="./logs/$​${date:yyyy-MM}/spring-boot-logger-log4j2-%d{-dd-MMMM-yyyy}-%i.log.gz">
            <PatternLayout>
                <pattern>%d %p %C{1.} [%t] %m%n</pattern>
            </PatternLayout>
            <Policies>
                <!-- rollover on startup, daily and when the file reaches 
                    10 MegaBytes -->
                <OnStartupTriggeringPolicy />
                <SizeBasedTriggeringPolicy
                    size="10 MB" />
                <TimeBasedTriggeringPolicy />
            </Policies>
        </RollingFile>
    </Appenders>

    <Loggers>
        <!-- LOG everything at INFO level -->
        <Root level="info">
            <AppenderRef ref="Console" />
            <AppenderRef ref="RollingFile" />
        </Root>

        <!-- LOG "com.baeldung*" at TRACE level -->
        <Logger name="com.baeldung" level="trace"></Logger>
    </Loggers>

</Configuration>

Spring Boot Log4j2 Demo - Using Slf4j

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Using Log4j2 via Slf4j

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@SpringBootApplication
public class Application extends SpringBootServletInitializer {

    private static final Logger log = LoggerFactory.getLogger(Application.class);

    public static void main(String[] args) {
        ApplicationContext ctx = SpringApplication.run(Application.class, args);

        log.info("Info level log message");
        log.debug("Debug level log message");
        log.error("Error level log message");
    }
}

see output

2018-06-01T13:55:42.506+0530 INFO Info level log message
2018-06-01T13:55:42.506+0530 DEBUG Debug level log message
2018-06-01T13:55:42.506+0530 ERROR Error level log message

Spring Boot Log4j2 Demo - Using Log4j2 Directly

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Using Log4j2 directly

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
 
@SpringBootApplication
public class Application extends SpringBootServletInitializer {
 
    private static final Logger log = LogManager.getLogger(Application.class);
 
    public static void main(String[] args) {
        ApplicationContext ctx = SpringApplication.run(Application.class, args);
         
        log.info("Info level log message");
        log.debug("Debug level log message");
        log.error("Error level log message");
    }
}