How to configure log4j to only keep log files for the last seven days?

Question

I have the following logging problem with several Java applications using log4j for logging:

I want log files to be rotated daily, like

log.2010-09-10
log.2010-09-09
log.2010-09-08
log.2010-09-07
log.2010-09-06
log.2010-09-05
log.2010-09-04

But for data security reasons we are not allowed to keep log files for longer than seven days at my company. So the generation of the next next log file log.2010-09-11 should trigger the deletion of log.2010-09-04. Is it possible to configure such a behaviour with log4j? If not, do you know another elegant solution for this kind of logging problem?

Answer 1

I assume you're using RollingFileAppender? In which case, it has a property called MaxBackupIndex which you can set to limit the number of files. For example:

log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=example.log
log4j.appender.R.MaxFileSize=100KB
log4j.appender.R.MaxBackupIndex=7
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n

Answer 2

There's also a DailyRollingFileAppender; http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/DailyRollingFileAppender.html

Edit: After reading this worrying statement;

DailyRollingFileAppender has been observed to exhibit synchronization issues and data loss. The log4j extras companion includes alternatives which should be considered for new deployments and which are discussed in the documentation for org.apache.log4j.rolling.RollingFileAppender.

from the above URL (which I never realised before), then this looks like a better bet; http://logging.apache.org/log4j/companions/extras/apidocs/index.html

Answer 3

According to the following post, you can't do this with log4j: http://stackoverflow.com/questions/896530/use-maxbackupindex-in-dailyrollingfileappender-log4j

As far as I know, this functionality was supposed to make it into log4j 2.0 but that effort got sidetracked. According to the logback website, logback is the intended successor to log4j so you might consider using that.

There's an API called SLF4J which provides a common API to logging. It will load up the actual logging implementation at runtime so depending on the configuration that you have provided, it might use java.util.log or log4j or logback or any other library capable of providing logging facilities. There'll be a bit of up from work to go from using log4j directly to using SLF4J but they provide some tools to automate this process. Once you've converted your code to use SLF4J, switching logging backends should simply be a case of changing the config file.

Answer 4

There is another option DailyRollingFileAppender. but it lacks the auto delete (keep 7 days log) feature you looking for

sample

log4j.appender.DRF=org.apache.log4j.DailyRollingFileAppender
log4j.appender.DRF.File=example.log
log4j.appender.DRF.DatePattern='.'yyyy-MM-dd

I do come across something call org.apache.log4j.CompositeRollingAppender, which is combine both the features of the RollingFileAppender (maxSizeRollBackups, no. of backup file) and DailyRollingFileAppender (roll by day).

But have not tried that out, seems is not the standard 1.2 branch log4j feature.

Answer 5

If you are using Linux, you can configure a cron job using tmpwatch.

Most Linux systems have a tmpwatch cron job that cleans up the /tmp directory. You can add another that monitors your logging directory and deletes files over 7 days old.

If you are using a different system, there are probably equivalent utilities.

Answer 6

You can perform your housekeeping in a separate script which can be cronned to run daily. Something like this:

find /path/to/logs -type f -mtime +7 -exec rm -f {} \;