Unable to use Spring Property Placeholders in logback.xml

Question

I have a Spring Boot console app using Logback. All of the properties (for the app as well as for Logback) are externalized into a standard application.properties file in th

Answer 1

${...} is not "Spring EL" in Spring; they are property placeholders.

I think you are confusing logback "variables" with Spring "Property Placeholders".

They just happen to use the same syntax ${...}.

logback knows nothing about the Spring property placeholder mechanism and vice-versa. You need to configure your logback variables according to the logback documentation and not in application.properties / application.yml which is strictly a Spring (boot) concept.

EDIT:

After a quick look at the logback docs, adding

<property resource="application.properties" />

to the logback.xml should work.

Answer 2

The solutions above work mostly for bootrap.properties. However, the only way to use properties from remote Spring Config Server in logback config I've currently found, is to apply them programatically:

@Component
public class LoggerConfiguration implements ApplicationListener<EnvironmentChangeEvent> {

    @Autowired protected Environment environment;

    @Override
    public void onApplicationEvent(EnvironmentChangeEvent event) {
        // enviroment here has already loaded all properties and you may alter logback config programatically
        ch.qos.logback.classic.Logger rootLogger = (ch.qos.logback.classic.Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
    }


}

Here is a good example how to customize logback with new appender this way.

Answer 3

As answered above you can access the spring boot properties using the <springProperty> element...but a thing to keep in mind is that the logback configuration file must be named logback-spring.xml, it doesn't work if you name the file logback.xml (I'm using spring-boot 1.3.5.RELEASE)

Answer 4

There is a way to map Spring properties to Logback properties and use them in the Conditions:

logback-spring.xml

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<include resource="org/springframework/boot/logging/logback/defaults.xml"/>
<springProperty scope="context" name="ACTIVE_PROFILE" source="spring.profiles.active"/>
<!--   defined in the application-prod.properties/>-->
<springProperty scope="context" name="SPRING_WRITER_DISABLED" source="writer.disabled"/>
<property name="LOGBACK_WRITER_DISABLED" value="${SPRING_WRITER_DISABLED}"/>

<if condition='property("LOGBACK_WRITER_DISABLED").equals("false")'>
    <then>
        <appender name="testappender" class="ch.qos.logback.core.rolling.RollingFileAppender">
            <file>${ACTIVE_PROFILE}/${HOSTNAME}/testappender.log</file>
            <rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
                <fileNamePattern>
                    {ACTIVE_PROFILE}/${HOSTNAME}/testappender-%d{yyyy-MM-dd}.%i.log
                </fileNamePattern>
                <maxFileSize>300MB</maxFileSize>
                <maxHistory>3</maxHistory>
                <totalSizeCap>1GB</totalSizeCap>
            </rollingPolicy>
            <encoder>
                <pattern>%msg%n</pattern>
            </encoder>
        </appender>
        <logger name="testappender" level="INFO" additivity="false">
            <appender-ref ref="testappender"/>
        </logger>
    </then>
</if>
</configuration>

Answer 5

Since Spring Boot 1.3 you have a better way of getting spring properties into your logback-spring.xml configuration:

Now you can just add a "springProperty" element.

<springProperty name="destination" source="my.loggger.extradest"/>
<appender name="FILE" class="ch.qos.logback.core.FileAppender">
    <file>${destination}</file>
        ...
    </file>
</appender>

https://github.com/spring-projects/spring-boot/commit/055ace37f006120b0006956b03c7f358d5f3729f

edit: thanks to Anders

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