INTRO
When you’re administering a remote server, logs are your best friend, but disk space problems can be your worst enemy - so while Linux applications are generally very good at generating logs, they need to be controlled.
The logrotate application keeps your logs in check. Using this, you can define how many days of logs you wish to keep; split them into manageable files; compress them to save space, or even keep them on a totally separate server.
Good sysadmins love automation - having the computer automatically do the boring repetitive stuff Just Makes Sense.
YOUR TASKS TODAY
- Check the logs for apache2 that are Severity 3
- Edit logrotate configuration for apache2 to rotate daily
ARE YOUR LOGS ROTATING?
Look into your logs directories - /var/log, and subdirectories like /var/log/apache2. Can you see that your logs are already being rotated? You should see a /var/log/syslog file, but also a series of older compressed versions with names like /var/log/syslog.1.gz
WHEN DO THEY ROTATE?
You will recall that cron is generally setup to run scripts in /etc/cron.daily - so look in there and you should see a script called logrotate - or possibly 00logrotate to force it to be the first task to run.
CONFIGURING LOGROTATE
The overall configuration is set in /etc/logrotate.conf - have a look at that, but then also look at the files under the directory /etc/logrotate.d, as the contents of these are merged in to create the full configuration. You will probably see one called apache2, with contents like this:
/var/log/apache2/*.log {
weekly
missingok
rotate 52
compress
delaycompress
notifempty
create 640 root adm
}
Much of this is fairly clear: any apache2 .log file will be rotated each week, with 52 compressed copies being kept.
Typically when you install an application a suitable logrotate “recipe” is installed for you, so you’ll not normally be creating these from scratch. However, the default settings won’t always match your requirements, so it’s perfectly reasonable for you as the sysadmin to edit these - for example, the default apache2 recipe above creates 52 weekly logs, but you might find it more useful to have logs rotated daily, a copy automatically emailed to an auditor, and just 30 days worth kept on the server.
RESOURCES
- The Ultimate Logrotate Command Tutorial
- LINUX: openSUSE and logrotate
- Use logrotate to Manage Log Files
TROUBLESHOOT AND MAKE A SAD SERVER HAPPY!
Practice what you've learned with some challenges at SadServers.com:
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