Change Apache Karaf default logging options

What you will do:

• Change the location of the Karaf log file
• Change the Karaf log file name, size, and retention rate
• Write Karaf system output to a log file

What you will learn:

• Overwrite default Karaf configuration files
• Create new directories in custom Karaf server
• Set Karaf environment variables

Please see the post "Create a custom Apache Karaf server" for the initial setup.

Apache Karaf has poor initial logging configurations for production.  Below are instructions on how to change it.

Step 1: Overwrite default Karaf logging configuration file

The default Karaf logging configuration file is etc/org.ops4j.pax.logging.cfg . The default Karaf log settings is to write to data/log/karaf.log , with a 1MB file size limit and a 10 file retention. To overwrite, create the file src/main/resources/etc/org.ops4j.pax.logging.cfg .  We are changing the log file to logs/dekantar.log, with a daily rotating log. 

The contents of etc/org.ops4j.pax.logging.cfg should look like

# Root logger
log4j.rootLogger=INFO, daily, osgi:*
log4j.throwableRenderer=org.apache.log4j.OsgiThrowableRenderer

# Daily File appender
log4j.appender.daily=org.apache.log4j.DailyRollingFileAppender
log4j.appender.daily.layout=org.apache.log4j.PatternLayout
log4j.appender.daily.layout.ConversionPattern=%d{ISO8601} | %-5.5p | %-16.16t | %-32.32c{1} | %X{bundle.id} - %X{bundle.name} - %X{bundle.version} | %m%n
log4j.appender.daily.file=${karaf.home}/logs/dekantar.log
log4j.appender.daily.datePattern='.'yyyy-MM-dd

See https://github.com/juttayaya/karaf/blob/master/karaf3/custom-karaf/custom-karaf-server/src/main/resources/etc/org.ops4j.pax.logging.cfg for a full example.

Step 2: Create the logs directory

Create the logs directory in /src/main/resources/logs.

See https://github.com/juttayaya/karaf/tree/master/karaf3/custom-karaf/custom-karaf-server/src/main/resources/logs for a full example

Step 3: Create the Karaf system output logfile

In Karaf 3.0.4, the Karaf system output log file is defined in the file bin/setenv as the variable KARAF_REDIRECT . If the variable is not defined, then the system output goes to /dev/null . In previous versions of Karaf 3, the system output logfile was hardcoded as data/log/karaf.out . 

To change the system output logfile to logs/dekantar.out , create the file src/main/resources/bin/setenv 

The content of bin/setenv should look like

#!/bin/sh

ENVHOME=`dirname $0`
LOG_HOME=`cd $ENVHOME/..;pwd`
export KARAF_REDIRECT=${LOG_HOME}/logs/dekantar.out

See https://github.com/juttayaya/karaf/blob/master/karaf3/custom-karaf/custom-karaf-server/src/main/resources/bin/setenv for full example.