If you need to apply customizations to logback beyond those that can be achieved with application.properties, you’ll need to add a standard logback configuration file. You can add a logback.xml file to the root of your classpath for logback to find. You can also use logback-spring.xml if you want to use the Spring Boot Logback extensions)

	Tip
	The Logback documentation has a dedicated section that covers configuration in some detail.

Spring Boot provides a number of logback configurations that be included from your own configuration. These includes are designed to allow certain common Spring Boot conventions to be re-applied.

The following files are provided under org/springframework/boot/logging/logback/:

In addition, a legacy base.xml file is provided for compatibility with earlier versions of Spring Boot.

A typical custom logback.xml file would look something like this:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
	<include resource="org/springframework/boot/logging/logback/defaults.xml"/>
	<include resource="org/springframework/boot/logging/logback/console-appender.xml" />
	<root level="INFO">
		<appender-ref ref="CONSOLE" />
	</root>
	<logger name="org.springframework.web" level="DEBUG"/>
</configuration>

Your logback configuration file can also make use of System properties that the LoggingSystem takes care of creating for you:

Spring Boot also provides some nice ANSI color terminal output on a console (but not in a log file) by using a custom Logback converter. See the CONSOLE_LOG_PATTERN in the defaults.xml configuration for an example.

If Groovy is on the classpath, you should be able to configure Logback with logback.groovy as well. If present, this setting is given preference.

	Note
	Spring extensions are not supported with Groovy configuration. Any logback-spring.groovy files will not be detected.

<?xml version="1.0" encoding="UTF-8"?>
<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}"/>
	<include resource="org/springframework/boot/logging/logback/file-appender.xml" />
	<root level="INFO">
		<appender-ref ref="FILE" />
	</root>
</configuration>

logging.file=myapplication.log

Spring Boot supports Log4j 2 for logging configuration if it is on the classpath. If you use the starters for assembling dependencies, you have to exclude Logback and then include log4j 2 instead. If you do not use the starters, you need to provide (at least) spring-jcl in addition to Log4j 2.

The simplest path is probably through the starters, even though it requires some jiggling with excludes. The following example shows how to set up the starters in Maven:

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<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>
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-log4j2</artifactId>
</dependency>

And the following example shows one way to set up the starters in Gradle:

dependencies {
	compile 'org.springframework.boot:spring-boot-starter-web'
	compile 'org.springframework.boot:spring-boot-starter-log4j2'
}

configurations {
	all {
		exclude group: 'org.springframework.boot', module: 'spring-boot-starter-logging'
	}
}

	Note
	The Log4j starters gather together the dependencies for common logging requirements (such as having Tomcat use java.util.logging but configuring the output using Log4j 2). See the Actuator Log4j 2 samples for more detail and to see it in action.

	Note
	To ensure that debug logging performed using java.util.logging is routed into Log4j 2, configure its JDK logging adapter by setting the java.util.logging.manager system property to org.apache.logging.log4j.jul.LogManager.