Chapter 12. JBoss AS Crash Course

The default AS7 configuration is shown below. It includes two handlers (one for the CONSOLE and one for the FILE), some loggers and a root logger. When a message is logged, here's what happens:

1. The message's category is compared to any defined <logger> elements. If a match is found, the message's level must be greater than or equal to that of the <logger>, else it's discarded.
2. If no matching <logger> is found, the message's level must be greater than or equal to the level of the <root-logger>, else it's discarded.
3. If it hasn't been discarded, the message is passed to all handlers associated with its <logger>, including those in the <root-logger>. Set the use-parent-handlers attribute of <logger> to "false" to override this behavior.
4. If the handler has no <level> threshold defined, as is the case for the FILE handler below, the message is logged.
5. If the handler has a <level> threshold defined, as is the case for the CONSOLE handler below, the message's level must be greater than or equal to that threshold to be logged.

Here's the default config from standalone/configuration/standalone.xml:

<subsystem xmlns="urn:jboss:domain:logging:1.2">
    <console-handler name="CONSOLE">
        <level name="INFO"/>
        <formatter>
            <pattern-formatter pattern="%K{level}%d{HH:mm:ss,SSS} %-5p [%c] (%t) %s%E%n"/>
        </formatter>
    </console-handler>
    <periodic-rotating-file-handler name="FILE" autoflush="true">
        <formatter>
            <pattern-formatter pattern="%d{HH:mm:ss,SSS} %-5p [%c] (%t) %s%E%n"/>
        </formatter>
        <file relative-to="jboss.server.log.dir" path="server.log"/>
        <suffix value=".yyyy-MM-dd"/>
        <append value="true"/>
    </periodic-rotating-file-handler>
    <logger category="com.arjuna">
        <level name="WARN"/>
    </logger>
    <logger category="org.apache.tomcat.util.modeler">
        <level name="WARN"/>
    </logger>
    <logger category="org.jboss.as.config">
        <level name="DEBUG"/>
    </logger>
    <logger category="sun.rmi">
        <level name="WARN"/>
    </logger>
    <logger category="jacorb">
        <level name="WARN"/>
    </logger>
    <logger category="jacorb.config">
        <level name="ERROR"/>
    </logger>
    <root-logger>
        <level name="INFO"/>
        <handlers>
            <handler name="CONSOLE"/>
            <handler name="FILE"/>
        </handlers>
    </root-logger>
</subsystem>

One thing to note about the default logging configuration is that your DEBUG messages won't show up anywhere. You could lower the default level for the root logger to DEBUG, but that results in DEBUG messages for every other category that doesn't match any of the loggers, potentially a lot of messages. A better solution is to define a <logger> specifically for your namespace:

<logger category='your.awesome.namespace'>
  <level name='DEBUG'/>
</logger>

This will result in log messages written to the FILE handler, but not the CONSOLE, since its threshold level is still set at INFO.

For many applications, it's usually better to take advantage of the hierarchical nature of categories and refer only to the top-level namespace component so that any messages logged from a child namespace will match. For example, this rule will cause debug messages logged from both your.awesome and your.awesome.namespace:

<logger category='your'>
  <level name='DEBUG'/>
</logger>

For more information, see the official JBoss logging documentation.

In addition to adjusting the logging settings globally in the xml configuration, you can also provide a log4j.properties, log4j.xml, or logging.properties file on the effective classpath for an application (i.e. in resources/, src/, etc.). These settings will only affect the logging for the application that provides the file.

For example, the following log4j.properties will cause all log messages from within the application (and from any Immutant namespaces called by the application) to be written to ~/my-app.log:

log4j.rootCategory=INFO, F

log4j.appender.F=org.apache.log4j.FileAppender
log4j.appender.F.append=true
log4j.appender.F.file=${user.home}/my-app.log
log4j.appender.F.layout=org.apache.log4j.PatternLayout
log4j.appender.F.layout.ConversionPattern=%d %-5p %c: %m%n

Note: due to a known issue with the logging system in the application server, configuring a console appender in log4j.properties/.xml won't work - no messages will be written to the console. The current workaround is to use a logging.properties file instead.

The following logging.properties will do the same as the above log4j.properties, but also display the messages in the console:

# Additional loggers to configure (the root logger is always configured)
loggers=

logger.level=INFO
logger.handlers=CONSOLE,FILE

handler.CONSOLE=org.jboss.logmanager.handlers.ConsoleHandler
handler.CONSOLE.level=TRACE
handler.CONSOLE.formatter=PATTERN
handler.CONSOLE.properties=autoFlush,target,enabled
handler.CONSOLE.autoFlush=true
handler.CONSOLE.target=SYSTEM_OUT
handler.CONSOLE.enabled=true

handler.FILE=org.jboss.logmanager.handlers.FileHandler
handler.FILE.level=ALL
handler.FILE.formatter=PATTERN
handler.FILE.properties=append,autoFlush,enabled,suffix,fileName
handler.FILE.constructorProperties=fileName,append
handler.FILE.append=true
handler.FILE.autoFlush=true
handler.FILE.enabled=true
handler.FILE.fileName=${user.home}/my-app.log

formatter.PATTERN=org.jboss.logmanager.formatters.PatternFormatter
formatter.PATTERN.properties=pattern
formatter.PATTERN.constructorProperties=pattern
formatter.PATTERN.pattern=%d %-5p %c: %m%n