Here is how we do this, by the way, we are using wildfly-8.1.0-Final.
First, make a jar file containing this class:
https://gist.github.com/xiaodong-xie/219491e0b433f8bd451e
Then put this jar file into "wildfly-8.1.0.Final/modules/system/layers/base/org/jboss/logmanager/main", and add a reference to this jar file in the module.xml file in the exact same folder.
Then put "logback-classic-1.1.2.jar" and "logback-core-1.1.2.jar" (You can use any version of logback you choose) into "wildfly-8.1.0.Final/modules/system/layers/base/org/jboss/logmanager/main", and reference those 2 jar files in the module.xml file.
Add the following to the "subsystem:logging" in the standalone.xml you are using:
<custom-handler name="logback" class="org.slf4j.bridge.SLF4JBridgeHandler" module="org.jboss.logmanager"></custom-handler>
And reference this handler in the root-logger element following:
<root-logger>
<level name="INFO"/>
<handlers>
<handler name="CONSOLE"/>
<handler name="logback"/>
</handlers>
</root-logger>
Here is an example of logback.xml:
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<contextListener class="ch.qos.logback.classic.jul.LevelChangePropagator"/>
<appender name="LOGFILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
<file>${JBOSS_HOME}/standalone/log/server-logback.log</file>
<append>true</append>
</appender>
<appender name="ASYNC" class="ch.qos.logback.classic.AsyncAppender">
<appender-ref ref="LOGFILE"/>
</appender>
<root level="INFO">
<appender-ref ref="ASYNC"/>
</root>
</configuration>
And put this logback.xml file into "wildfly-8.1.0.Final/standalone/configuration" folder.
Add the following to the "standalone.sh" or equivalent in the "wildfly-8.1.0.Final/bin" folder.
-Dlogback.configurationFile=file:$JBOSS_CONFIG_DIR/logback.xml
Just under "-Dlogging.configuration=file:$JBOSS_CONFIG_DIR/logging.properties" line. There are 2 places in "standalone.sh" file.
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Or you can do it in a simpler way. :)
Put the 2 logback jar files to the "jboss.logmanager" module, and add "-Dorg.jboss.logging.provider=slf4j" to the "standalone.sh" file, the same position.
I found there are some logging missing if going this by the way, since Wildfly itself still using its own logging facility if going this way.
Have fun. :-)