Tomcat - Logger

The Logger Component

Overview
A Logger element represents a destination for logging, debugging, and error messages (including stack tracebacks) for a Catalina container (Engine, Host, or Context). In addition, Loggers associated with an Engine or a Host are automatically inherited by lower-level containers, unless explicitly overridden.

If you are interested in producing access logs like a web server does (for example, to run hit count analysis software), you will want to configure an Access Log Valve component on your Engine, Host, or Context.

The verbosity attribute is the the verbosity level for this logger. Messages with a higher verbosity level than the specified value will be silently ignored. Available levels are 0 (fatal messages only), 1 (errors), 2 (warnings), 3 (information), and 4 (debug). If not specified, the default value will be 1 (error).

Only messages logged with an explicit verbosity level are compared to this value. Messages logged with no explicit verbosity level are logged unconditionally.

Standard Implementation

Unlike most Catalina components, there are several standard Logger implementations available. As a result, the className attribute MUST be used to select the implementation you wish to use.

File Logger (org.apache.catalina.logger.FileLogger)

The File Logger records all logged messages to disk file(s) in a specified directory. The actual filenames of the log files are created from a configured prefix, the current date in YYYY-MM-DD format, and a configured suffix. On the first logged message after midnight each day, the current log file will be closed and a new file opened for the new date, without having to shut down Catalina in order to perform this switch.

The File Logger supports the following attributes:

Attribute Description

directory Absolute or relative pathname of a directory in which log files created by this logger will be placed. If a relative path is specified, it is interpreted as relative to $CATALINA_HOME. If no directory attribute is specified, the default value is "logs" (relative to $CATALINA_HOME).

prefix The prefix added to the start of each log file's name. If not specified, the default value is "catalina.". To specify no prefix, use a zero-length string.

suffix The suffix added to the end of each log file's name. If not specified, the default value is ".log". To specify no suffix, use a zero-length string.

timestamp Set to true to cause all logged messages to be date and time stamped. Set to false (the default) to skip date/time stamping.

Standard Error Logger (org.apache.catalina.logger.SystemErrLogger)

The Standard Error Logger records all logged messages to whatever stream the standard error output of Catalina is pointed at. The default Catalina startup script points this at file logs/catalina.out relative to $CATALINA_HOME. This logger supports no additional attributes.

Standard Output Logger (org.apache.catalina.logger.SystemOutLogger)

The Standard Output Logger records all logged messages to whatever stream the standard output of Catalina is pointed at. The default Catalina startup script points this at file logs/catalina.out relative to $CATALINA_HOME. This logger supports no additional attributes.

Attribute	Description
directory	Absolute or relative pathname of a directory in which log files created by this logger will be placed. If a relative path is specified, it is interpreted as relative to $CATALINA_HOME. If no directory attribute is specified, the default value is "logs" (relative to $CATALINA_HOME).
prefix	The prefix added to the start of each log file's name. If not specified, the default value is "catalina.". To specify no prefix, use a zero-length string.
suffix	The suffix added to the end of each log file's name. If not specified, the default value is ".log". To specify no suffix, use a zero-length string.
timestamp	Set to true to cause all logged messages to be date and time stamped. Set to false (the default) to skip date/time stamping.