Links User Guide Reference Apache Tomcat Development | Logging in Tomcat| Introduction |
Tomcat uses
Commons Logging
throughout its internal code allowing the
developer to choose a logging configuration that suits their needs, e.g
java.util.logging or
Log4J.
Commons Logging provides Tomcat with the ability to log
hierarchically across various log levels without needing to rely on a
particular logging implementation.
By default, only java.util.logging is available for the logs generated by
the Tomcat internal loggers, as Tomcat uses a package renamed commons
logging implementation which is hardcoded to use java.util.logging. Use of
alternative logging frameworks requires building or downloading the
extras components which include a full
commons-logging implementation. Instructions for configuring the extras
components to enable log4j to be used for Tomcat's internal logging may be
found below.
Tomcat no longer uses localhost_log as the runtime
exception/stack trace log. These types of error are usually thrown by
uncaught exceptions, but are still valuable to the developer. They can now
be found in the stdout log.
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| java.util.logging |
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:
- In the JDK's logging.properties file. Check your JAVA_HOME environment
setting to see which JDK Tomcat is using. The file will be in
$JAVA_HOME/jre/lib.
Alternately, it can also use a global configuration file located elsewhere
by using the system property java.util.logging.config.file,
or programmatic configuration using
java.util.logging.config.class.
- In each classloader using a logging.properties file. This means that
it is possible to have a configuration for the Tomcat core, as well as
separate configurations for each webapps which will have the same
lifecycle as the webapps.
The default logging.properties specifies a ConsoleHandler for routing
logging to stdout and also a FileHandler. A handler's log level threshold
can be set using SEVERE, WARNING, INFO, CONFIG, FINE, FINER, FINEST or ALL.
The logging.properties shipped with JDK is set to INFO. 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 level is also set to collect this threshold, so FINEST or
ALL should be set. Please refer to Sun's java.util.logging documentation for
the complete details.
 | | | | org.apache.catalina.level=FINEST | | | | |
The configuration used by JULI is extremely similar, 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.
- 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 the
loggerName.useParentHandlers property, which accepts a
boolean value.
- The root logger can define its set of handlers using a
.handlers property.
- Logging is not buffered by default. To configure buffering, use the
bufferSize 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.
- System property replacement is performed for property values which
contain ${systemPropertyName}.
Example logging.properties file to be placed in $CATALINA_BASE/conf:
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handlers = 1catalina.org.apache.juli.FileHandler, \
2localhost.org.apache.juli.FileHandler, \
3manager.org.apache.juli.FileHandler, \
4admin.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 = FINE
1catalina.org.apache.juli.FileHandler.directory = ${catalina.base}/logs
1catalina.org.apache.juli.FileHandler.prefix = catalina.
2localhost.org.apache.juli.FileHandler.level = FINE
2localhost.org.apache.juli.FileHandler.directory = ${catalina.base}/logs
2localhost.org.apache.juli.FileHandler.prefix = localhost.
3manager.org.apache.juli.FileHandler.level = FINE
3manager.org.apache.juli.FileHandler.directory = ${catalina.base}/logs
3manager.org.apache.juli.FileHandler.prefix = manager.
4admin.org.apache.juli.FileHandler.level = FINE
4admin.org.apache.juli.FileHandler.directory = ${catalina.base}/logs
4admin.org.apache.juli.FileHandler.prefix = admin.
4admin.org.apache.juli.FileHandler.bufferSize = 16384
java.util.logging.ConsoleHandler.level = FINE
java.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 = INFO
org.apache.catalina.core.ContainerBase.[Catalina].[localhost].handlers = \
2localhost.org.apache.juli.FileHandler
org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/manager].level = INFO
org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/manager].handlers = \
3manager.org.apache.juli.FileHandler
org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/admin].level = INFO
org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/admin].handlers = \
4admin.org.apache.juli.FileHandler
# For example, set the org.apache.catalina.util.LifecycleBase logger to log
# each component that extends LifecycleBase changing state:
#org.apache.catalina.util.LifecycleBase.level = FINE
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Example logging.properties for the servlet-examples web application to be
placed in WEB-INF/classes inside the web application:
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handlers = org.apache.juli.FileHandler, java.util.logging.ConsoleHandler
############################################################
# Handler specific properties.
# Describes specific configuration info for Handlers.
############################################################
org.apache.juli.FileHandler.level = FINE
org.apache.juli.FileHandler.directory = ${catalina.base}/logs
org.apache.juli.FileHandler.prefix = servlet-examples.
java.util.logging.ConsoleHandler.level = FINE
java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter
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| log4j |
This section explains how to configure Tomcat to use log4j rather than
java.util.logging for all Tomcat's internal logging. The following steps
describe configuring log4j to output Tomcat's internal logging to a file
named tomcat.log.
- Create a file called log4j.properties with the following content
and save it into $CATALINA_HOME/lib.
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log4j.rootLogger=INFO, R
log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=${catalina.base}/logs/tomcat.log
log4j.appender.R.MaxFileSize=10MB
log4j.appender.R.MaxBackupIndex=10
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n
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- Download Log4J
(v1.2 or later) and place the log4j jar in $CATALINA_HOME/lib.
- Build or download the additional logging components. See the
extras components documentation for
details.
- Replace
$CATALINA_HOME/bin/tomcat-juli.jar with
output/extras/tomcat-juli.jar.
- Place
output/extras/tomcat-juli-adapters.jar in
$CATALINA_HOME/lib.
- Delete
$CATALINA_BASE/conf/logging.properties to
prevent java.util.logging generating zero length log files.
- Start Tomcat
This log4j configuration sets up a file called tomcat.log in your
Tomcat logs folder with a maximum file size of 10MB and
up to 10 backups. INFO level is specified which will result in a similar
level of detail to the standard java.util.logging confgiuration. Use DEBUG
level logging for the most verbose output from Tomcat.
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.
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log4j.logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost]=DEBUG
log4j.logger.org.apache.catalina.core=DEBUG
log4j.logger.org.apache.catalina.session=DEBUG
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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.
If you have multiple instances of Tomcat, each with a separate
$CATALINA_BASE but a shared $CATALINA_HOME then
you can configure log4j on a per instance basis by replacing references to
$CATALINA_HOME in the above instructions with
$CATALINA_BASE. Note that if you do this then you may need to
make some, or all, of the following additional changes:
- create a
$CATALINA_BASE/bin directory
- create a
$CATALINA_BASE/lib directory
- if running with a security manager, adjust the codebase for JULI in
$CATALINA_BASE/conf/catalina.policy
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