Using java.util.logging (default)

 Using java.util.logging (default)

The default implementation of java.util.logging provided in the JDK is too limited to be useful. A limitation of JDK Logging appears to be the inability to have per-web application logging, as the configuration is per-VM. As a result, Tomcat will, in the default configuration, replace the default LogManager implementation with a container friendly implementation called JULI, which addresses these shortcomings. It supports the same configuration mechanisms as the standard JDK java.util.logging, using either a programmatic approach, or properties files. The main difference is that per-classloader properties files can be set (which enables easy redeployment friendly webapp configuration), and the properties files support slightly extended constructs which allows more freedom for defining handlers and assigning them to loggers.

JULI is enabled by default, and supports per classloader configuration, in addition to the regular global java.util.logging configuration. This means that logging can be configured at the following layers:

• Globally. That is usually done in the ${catalina.base}/conf/logging.properties file. The file is specified by thejava.util.logging.config.file System property which is set by the startup scripts. If it is not readable or is not configured, the default is to use the${java.home}/lib/logging.properties file in the JRE.
• In the web application. The file will be WEB-INF/classes/logging.properties

The default logging.properties in the JRE specifies a ConsoleHandler that routes logging to System.err. The defaultconf/logging.properties in Apache Tomcat also adds several FileHandlers that write to files.

A handler's log level threshold is INFO by default and can be set using SEVERE, WARNING, INFO, CONFIG, FINE, FINER, FINEST or ALL. You can also target specific packages to collect logging from and specify a level.

Here is how you would set debugging from Tomcat. You would need to ensure the ConsoleHandler's (or FileHandler's') level is also set to collect this threshold, so FINEST or ALL should be set. Please refer tojava.util.logging documentation in the JDK for the complete details:

org.apache.catalina.level=FINEST

The configuration used by JULI is extremely similar to the one supported by plainjava.util.logging, but uses a few extensions to allow better flexibility in assigning loggers. The main differences are:

• A prefix may be added to handler names, so that multiple handlers of a single class may be instantiated. A prefix is a String which starts with a digit, and ends with '.'. For example,22foobar. is a valid prefix.
• System property replacement is performed for property values which contain ${systemPropertyName}.
• As in Java 6.0, loggers can define a list of handlers using the loggerName.handlers property.
• By default, loggers will not delegate to their parent if they have associated handlers. This may be changed per logger using theloggerName.useParentHandlers property, which accepts a boolean value.
• The root logger can define its set of handlers using the .handlers property.

There are several additional implementation classes, that can be used together with the ones provided by Java. The notable one isorg.apache.juli.FileHandler.

org.apache.juli.FileHandler supports buffering of the logs. The buffering is not enabled by default. To configure it, use thebufferSize property of a handler. A value of 0 uses system default buffering (typically an 8K buffer will be used). A value of<0 forces a writer flush upon each log write. A value >0 uses a BufferedOutputStream with the defined value but note that the system default buffering will also be applied.

Example logging.properties file to be placed in $CATALINA_BASE/conf:

handlers = 1catalina.org.apache.juli.FileHandler, \           2localhost.org.apache.juli.FileHandler, \           3manager.org.apache.juli.FileHandler, \           java.util.logging.ConsoleHandler.handlers = 1catalina.org.apache.juli.FileHandler, java.util.logging.ConsoleHandler############################################################# Handler specific properties.# Describes specific configuration info for Handlers.############################################################1catalina.org.apache.juli.FileHandler.level = FINE1catalina.org.apache.juli.FileHandler.directory = ${catalina.base}/logs1catalina.org.apache.juli.FileHandler.prefix = catalina.2localhost.org.apache.juli.FileHandler.level = FINE2localhost.org.apache.juli.FileHandler.directory = ${catalina.base}/logs2localhost.org.apache.juli.FileHandler.prefix = localhost.3manager.org.apache.juli.FileHandler.level = FINE3manager.org.apache.juli.FileHandler.directory = ${catalina.base}/logs3manager.org.apache.juli.FileHandler.prefix = manager.3manager.org.apache.juli.FileHandler.bufferSize = 16384java.util.logging.ConsoleHandler.level = FINEjava.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter############################################################# Facility specific properties.# Provides extra control for each logger.############################################################org.apache.catalina.core.ContainerBase.[Catalina].[localhost].level = INFOorg.apache.catalina.core.ContainerBase.[Catalina].[localhost].handlers = \   2localhost.org.apache.juli.FileHandlerorg.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/manager].level = INFOorg.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/manager].handlers = \   3manager.org.apache.juli.FileHandler# For example, to log debug messages in ContextConfig and HostConfig# classes and to log only warnings and errors in other# org.apache.catalina.** classes, uncomment these lines:#org.apache.catalina.startup.ContextConfig.level = FINE#org.apache.catalina.startup.HostConfig.level = FINE#org.apache.catalina.level = WARNING

Example logging.properties for the servlet-examples web application to be placed in WEB-INF/classes inside the web application:

handlers = org.apache.juli.FileHandler, java.util.logging.ConsoleHandler############################################################# Handler specific properties.# Describes specific configuration info for Handlers.############################################################org.apache.juli.FileHandler.level = FINEorg.apache.juli.FileHandler.directory = ${catalina.base}/logsorg.apache.juli.FileHandler.prefix = servlet-examples.java.util.logging.ConsoleHandler.level = FINEjava.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter

Documentation references

See the following resources for additional information:

• Apache Tomcat Javadoc for the org.apache.juli package.
• Oracle Java 6 Javadoc for the java.util.logging package.

Considerations for productive usage

You may want to take note of the following:

• Consider removing ConsoleHandler from configuration.

  By default (thanks to the .handlers setting) logging goes both to aFileHandler and to a ConsoleHandler. The output of the latter one is usually captured into a file, such ascatalina.out. Thus you end up with two copies of the same messages.

• Consider removing FileHandlers for the applications that you do not use. E.g., the one forhost-manager.

• The handlers by default use the system default encoding to write the log files. It can be configured withencoding property. See Javadoc for details.

• Consider configuring an Access log.

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 arenot needed if you just want to use log4j in your own web application. — In that case, just putlog4j.jar and log4j.properties into WEB-INF/lib andWEB-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 appenderslog4j.appender.CATALINA=org.apache.log4j.DailyRollingFileAppenderlog4j.appender.CATALINA.File=${catalina.base}/logs/catalina.log4j.appender.CATALINA.Append=truelog4j.appender.CATALINA.Encoding=UTF-8# Roll-over the log once per daylog4j.appender.CATALINA.DatePattern='.'yyyy-MM-dd'.log'log4j.appender.CATALINA.layout = org.apache.log4j.PatternLayoutlog4j.appender.CATALINA.layout.ConversionPattern = %d [%t] %-5p %c- %m%nlog4j.appender.LOCALHOST=org.apache.log4j.DailyRollingFileAppenderlog4j.appender.LOCALHOST.File=${catalina.base}/logs/localhost.log4j.appender.LOCALHOST.Append=truelog4j.appender.LOCALHOST.Encoding=UTF-8log4j.appender.LOCALHOST.DatePattern='.'yyyy-MM-dd'.log'log4j.appender.LOCALHOST.layout = org.apache.log4j.PatternLayoutlog4j.appender.LOCALHOST.layout.ConversionPattern = %d [%t] %-5p %c- %m%nlog4j.appender.MANAGER=org.apache.log4j.DailyRollingFileAppenderlog4j.appender.MANAGER.File=${catalina.base}/logs/manager.log4j.appender.MANAGER.Append=truelog4j.appender.MANAGER.Encoding=UTF-8log4j.appender.MANAGER.DatePattern='.'yyyy-MM-dd'.log'log4j.appender.MANAGER.layout = org.apache.log4j.PatternLayoutlog4j.appender.MANAGER.layout.ConversionPattern = %d [%t] %-5p %c- %m%nlog4j.appender.HOST-MANAGER=org.apache.log4j.DailyRollingFileAppenderlog4j.appender.HOST-MANAGER.File=${catalina.base}/logs/host-manager.log4j.appender.HOST-MANAGER.Append=truelog4j.appender.HOST-MANAGER.Encoding=UTF-8log4j.appender.HOST-MANAGER.DatePattern='.'yyyy-MM-dd'.log'log4j.appender.HOST-MANAGER.layout = org.apache.log4j.PatternLayoutlog4j.appender.HOST-MANAGER.layout.ConversionPattern = %d [%t] %-5p %c- %m%nlog4j.appender.CONSOLE=org.apache.log4j.ConsoleAppenderlog4j.appender.CONSOLE.Encoding=UTF-8log4j.appender.CONSOLE.layout = org.apache.log4j.PatternLayoutlog4j.appender.CONSOLE.layout.ConversionPattern = %d [%t] %-5p %c- %m%n# Configure which loggers log to which appenderslog4j.logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost]=INFO, LOCALHOSTlog4j.logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/manager]=\  INFO, MANAGERlog4j.logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/host-manager]=\  INFO, HOST-MANAGER

2. Download Log4J (v1.2 or later).

3. Download or build tomcat-juli.jar and tomcat-juli-adapters.jar that are available as an "extras" component for Tomcat. SeeAdditional 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.

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

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

5. 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 into $CATALINA_BASE/lib
   • Put tomcat-juli.jar from "extras" as $CATALINA_BASE/bin/tomcat-juli.jar
   • Put tomcat-juli-adapters.jar from "extras" into $CATALINA_BASE/lib
   • 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 $CATALINA_HOME/bin is still referenced by manifest ofbootstrap.jar and thus will be implicitly present on Tomcat's classpath. The startup scripts configure$CATALINA_BASE/bin/tomcat-juli.jar to be earlier on the classpath thanbootstrap.jar, and so it should have higher priority. Thus it should be OK, but consider removing the unneeded copy oftomcat-juli.jar (copy it into all other $CATALINA_BASEs that do not use log4j). Tomcat 7 does not have this issue.

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

7. 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]=DEBUGlog4j.logger.org.apache.catalina.core=DEBUGlog4j.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 validwith 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. Seeclass loading documentation 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.