By default, the SLF4j Logging is included in the Spring Boot starter package.

spring-boot-web-project$ mvn dependency:tree

+...
+- org.springframework.boot:spring-boot-starter-logging:jar:1.4.2.RELEASE:compile
[INFO] |  |  |  +- ch.qos.logback:logback-classic:jar:1.1.7:compile
[INFO] |  |  |  |  \- ch.qos.logback:logback-core:jar:1.1.7:compile
[INFO] |  |  |  +- org.slf4j:jcl-over-slf4j:jar:1.7.21:compile
[INFO] |  |  |  +- org.slf4j:jul-to-slf4j:jar:1.7.21:compile
[INFO] |  |  |  \- org.slf4j:log4j-over-slf4j:jar:1.7.21:compile
+...

1. application.properties

To enable logging, create a application.properties file in the root of the resources folder.

1.1 logging.level – define logging level, the logging will be output to console.

logging.level.org.springframework.web=ERROR
logging.level.com.mkyong=DEBUG

1.2 logging.file – define logging file, the logging will be output to a file and console.

logging.level.org.springframework.web=ERROR
logging.level.com.mkyong=DEBUG

#output to a temp_folder/file
logging.file=${java.io.tmpdir}/application.log

#output to a file
#logging.file=/Users/mkyong/application.log

1.3 logging.pattern – define a custom logging pattern.

logging.level.org.springframework.web=ERROR
logging.level.com.mkyong=DEBUG

# Logging pattern for the console
logging.pattern.console= "%d{yyyy-MM-dd HH:mm:ss} - %msg%n"

# Logging pattern for file
logging.pattern.file= "%d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %logger{36} - %msg%n"

logging.file=/Users/mkyong/application.log

2. application.yml

This is the equivalent in YAML format.

logging:
  level:
    org.springframework.web: ERROR
    com.mkyong: DEBUG
  pattern:
    console: "%d{yyyy-MM-dd HH:mm:ss} - %msg%n"
    file: "%d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %logger{36} - %msg%n"
  file: /Users/mkyong/application.log

3. Classic Logback.xml

If you don’t like the Spring Boot logging template, just create a standard logback.xml in the root of the resourcesfolder or root of the classpath. This will override the Spring Boot logging template.

<configuration>

    <property name="DEV_HOME" value="c:/logs" />

    <appender name="FILE-AUDIT"
        class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>${DEV_HOME}/debug.logfile>
        <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
            <Pattern>
                %d{yyyy-MM-dd HH:mm:ss} - %msg%n
            Pattern>
        encoder>

        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            
            <fileNamePattern>${DEV_HOME}/archived/debug.%d{yyyy-MM-dd}.%i.log
                        fileNamePattern>
            <timeBasedFileNamingAndTriggeringPolicy
                class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
                <maxFileSize>10MBmaxFileSize>
            timeBasedFileNamingAndTriggeringPolicy>
        rollingPolicy>

    appender>

    <logger name="com.mkyong" level="debug"
        additivity="false">
        <appender-ref ref="FILE-AUDIT" />
    logger>

    <root level="error">
        <appender-ref ref="FILE-AUDIT" />
    root>

configuration>

4. Spring Boot logging by Profile

Create a logback-spring.xml in the root of the classpath, to take advantage of the templating features provided by Spring Boot.

In below example :

1. If the profile is dev, logs to console and a rolling file.
2. If the profile is prod, logs to a rolling file only.

<configuration>
    <include resource="org/springframework/boot/logging/logback/defaults.xml"/>
    <property name="LOG_FILE" value="${LOG_FILE:-${LOG_PATH:-${LOG_TEMP:-${java.io.tmpdir:-/tmp}}/}spring.log}"/>

    <springProfile name="dev">
        <include resource="org/springframework/boot/logging/logback/console-appender.xml"/>
        <appender name="ROLLING-FILE"
                  class="ch.qos.logback.core.rolling.RollingFileAppender">
            <encoder>
                <pattern>${FILE_LOG_PATTERN}pattern>
            encoder>
            <file>${LOG_FILE}file>
            <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
                <fileNamePattern>${LOG_FILE}.%d{yyyy-MM-dd}.logfileNamePattern>
            rollingPolicy>
        appender>
        <root level="ERROR">
            <appender-ref ref="CONSOLE"/>
            <appender-ref ref="ROLLING-FILE"/>
        root>
    springProfile>

    <springProfile name="prod">
        <appender name="ROLLING-FILE"
                  class="ch.qos.logback.core.rolling.RollingFileAppender">
            <encoder>
                <pattern>${FILE_LOG_PATTERN}pattern>
            encoder>
            <file>${LOG_FILE}file>
            <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
                <fileNamePattern>${LOG_FILE}.%d{yyyy-MM-dd}.%i.gzfileNamePattern>
                <timeBasedFileNamingAndTriggeringPolicy
                        class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
                    <maxFileSize>10MBmaxFileSize>
                timeBasedFileNamingAndTriggeringPolicy>
            rollingPolicy>
        appender>

        <root level="ERROR">
            <appender-ref ref="ROLLING-FILE"/>
        root>
    springProfile>

configuration>

spring:
  profiles:
    active: prod

logging:
  level:
    ROOT: ERROR
    org.springframework: ERROR
    org.springframework.data: ERROR
    com.mkyong: INFO
    org.mongodb: ERROR
  file: /Users/mkyong/application.log

For non-web boot app, you can override the log file output like this :

$ java -Dlogging.file=/home/mkyong/app/logs/app.log -jar boot-app.jar

5. Set Root Level

# root logging level, warning : too much output
logging.level.=DEBUG

logging:
  level:
    ROOT: DEBUG

Download Source Code

References

1. Spring Boot – How to Logging
2. Spring Boot Logback XML template
3. Spring Boot: How can I set the logging level with application.properties?
4. logback.xml Examples
5. Logback Home