Using Log4j in Tomcat 6.0.x & 7.0.x

The paper is part of http://tomcat.apache.org/tomcat-6.0-doc/logging.html

 

Using Log4j

This section explains how to configure Tomcat to use log4j rather than java.util.logging for all Tomcat's internal logging.

Note: The steps described in this section are needed when you want to reconfigure Tomcat to use Apache log4j for its own logging. These steps are not needed if you just want to use log4j in your own web application. — In that case, just put log4j.jar and log4j.properties into WEB-INF/lib and WEB-INF/classes of your web application.

The following steps describe configuring log4j to output Tomcat's internal logging.

1. Create a file called log4j.properties with the following content and save it into $CATALINA_BASE/lib

	log4j.rootLogger=INFO, CATALINA # Define all the appenders log4j.appender.CATALINA=org.apache.log4j.DailyRollingFileAppender log4j.appender.CATALINA.File=${catalina.base}/logs/catalina. log4j.appender.CATALINA.Append=true log4j.appender.CATALINA.Encoding=UTF-8 # Roll-over the log once per day log4j.appender.CATALINA.DatePattern='.'yyyy-MM-dd'.log' log4j.appender.CATALINA.layout = org.apache.log4j.PatternLayout log4j.appender.CATALINA.layout.ConversionPattern = %d [%t] %-5p %c- %m%n log4j.appender.LOCALHOST=org.apache.log4j.DailyRollingFileAppender log4j.appender.LOCALHOST.File=${catalina.base}/logs/localhost. log4j.appender.LOCALHOST.Append=true log4j.appender.LOCALHOST.Encoding=UTF-8 log4j.appender.LOCALHOST.DatePattern='.'yyyy-MM-dd'.log' log4j.appender.LOCALHOST.layout = org.apache.log4j.PatternLayout log4j.appender.LOCALHOST.layout.ConversionPattern = %d [%t] %-5p %c- %m%n log4j.appender.MANAGER=org.apache.log4j.DailyRollingFileAppender log4j.appender.MANAGER.File=${catalina.base}/logs/manager. log4j.appender.MANAGER.Append=true log4j.appender.MANAGER.Encoding=UTF-8 log4j.appender.MANAGER.DatePattern='.'yyyy-MM-dd'.log' log4j.appender.MANAGER.layout = org.apache.log4j.PatternLayout log4j.appender.MANAGER.layout.ConversionPattern = %d [%t] %-5p %c- %m%n log4j.appender.HOST-MANAGER=org.apache.log4j.DailyRollingFileAppender log4j.appender.HOST-MANAGER.File=${catalina.base}/logs/host-manager. log4j.appender.HOST-MANAGER.Append=true log4j.appender.HOST-MANAGER.Encoding=UTF-8 log4j.appender.HOST-MANAGER.DatePattern='.'yyyy-MM-dd'.log' log4j.appender.HOST-MANAGER.layout = org.apache.log4j.PatternLayout log4j.appender.HOST-MANAGER.layout.ConversionPattern = %d [%t] %-5p %c- %m%n log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender log4j.appender.CONSOLE.Encoding=UTF-8 log4j.appender.CONSOLE.layout = org.apache.log4j.PatternLayout log4j.appender.CONSOLE.layout.ConversionPattern = %d [%t] %-5p %c- %m%n # Configure which loggers log to which appenders log4j.logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost]=INFO, LOCALHOST log4j.logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/manager]=\ INFO, MANAGER log4j.logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/host-manager]=\ INFO, HOST-MANAGER

1. Download Log4J (v1.2 or later).

2. Download or build tomcat-juli.jar and tomcat-juli-adapters.jar that are available as an "extras" component for Tomcat. See Additional Components documentation for details.

   This tomcat-juli.jar differs from the default one. It contains the full Apache Commons Logging implementation and thus is able to discover the presense of log4j and configure itself.

3. If you want to configure Tomcat to use log4j globally:

   • Put log4j.jar and tomcat-juli-adapters.jar from "extras" into $CATALINA_HOME/lib.
   • Replace $CATALINA_HOME/bin/tomcat-juli.jar with tomcat-juli.jar from "extras".

4. If you are running Tomcat with separate $CATALINA_HOME and $CATALINA_BASE and want to configure to use log4j in a single $CATALINA_BASE only:

   • Create $CATALINA_BASE/bin and $CATALINA_BASE/lib directories if they do not exist.
   • Put log4j.jar and tomcat-juli-adapters.jar from "extras" into $CATALINA_BASE/lib
   • Put tomcat-juli.jar from "extras" as $CATALINA_BASE/bin/tomcat-juli.jar
   • If you are running with a security manager, you would need to edit the$CATALINA_BASE/conf/catalina.policy file to adjust it to using a different copy of tomcat-juli.jar.
   • The old tomcat-juli.jar in $CATALINA_HOME/bin is still referenced by manifest of bootstrap.jar and thus will be implicitly present on Tomcat's classpath. The startup scripts configure$CATALINA_BASE/bin/tomcat-juli.jar to be earlier on the classpath than bootstrap.jar, and so it should have higher priority. Thus it should be OK, but consider removing the unneeded copy of tomcat-juli.jar (copy it into all other $CATALINA_BASEs that do not use log4j). Tomcat 7 does not have this issue.

5. Delete $CATALINA_BASE/conf/logging.properties to prevent java.util.logging generating zero length log files.

6. Start Tomcat

This log4j configuration mirrors the default java.util.logging setup that ships with Tomcat: both the manager and host-manager apps get an individual log file, and everything else goes to the "catalina.log" log file. Each file is rolled-over once per day.

You can (and should) be more picky about which packages to include in the logging. Tomcat defines loggers by Engine and Host names. For example, for a more detailed Catalina localhost log, add this to the end of the log4j.properties above. Note that there are known issues with using this naming convention (with square brackets) in log4j XML based configuration files, so we recommend you use a properties file as described until a future version of log4j allows this convention.

	log4j.logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost]=DEBUG log4j.logger.org.apache.catalina.core=DEBUG log4j.logger.org.apache.catalina.session=DEBUG

Be warned: a level of DEBUG will produce megabytes of logging and slow startup of Tomcat. This level should be used sparingly when debugging of internal Tomcat operations is required.

Your web applications should certainly use their own log4j configuration. This is valid with the above configuration. You would place a similar log4j.properties file in your web application's WEB-INF/classes directory, and log4jx.y.z.jar into WEB-INF/lib. Then specify your package level logging. This is a basic setup of log4j which does *not* require Commons-Logging, and you should consult the log4j documentation for more options. This page is intended only as a bootstrapping guide.

Additional notes

• This exposes log4j libraries to the web applications through the Common classloader. See class loadingdocumentation for details.

  Because of that, the web applications and libraries using Apache Commons Logging library are likely to automatically choose log4j as the underlying logging implementation.

• The java.util.logging API is still available, for those web applications that use it directly. The${catalina.base}/conf/logging.properties file is still referenced by Tomcat startup scripts.

  Removal of ${catalina.base}/conf/logging.properties file, mentioned as one of the steps, just causesjava.util.logging to fallback to the default configuration as configured in JRE, which is to use a ConsoleHandler and do not create any files.