Manage log files with Logrotate

Did you ever have to check a log file and when tried to open, it was huge?
I have, depressing.
So what? Logrotate it!

From package description:

“logrotate is designed to ease administration of systems that generate
large numbers of log files. It allows automatic rotation, compression,
removal, and mailing of log files. Each log file may be handled daily,
weekly, monthly, or when it grows too large.”

How to handle logs with logrotate?

The sample code here was used on Ubuntu 16.04, but I’m sure you will figure out how to make it work on your system.

Step 1: Install it, if not installed yet

Ubuntu 16.04 already have Logrotate installed, but anyway.

sudo apt-get update
sudo apt-get install logrotate

Step 2: Add you app specific file

Specific files are located on:

/etc/logrotate.d/

Create a file like:

/etc/logrotate.d/[your_app_name]

With a content like this:

/path/to/your/log/file.log {
  daily
  missingok
  rotate 30
  compress
  delaycompress
  notifempty
  copytruncate
}

The options means:

• daily – do it every day
• missingok – if no log, no problem, no error
• rotate 30 – keep 30 old files, or in our case, keep 30 days of log
• compress – compress the old files
• delaycompress – delay the file compressing action, nice to avoid write concurrency in the log file
• notifempty – if no content on log file, do nothing
• copytruncate – truncate the original log file in place after creating a copy, instead of moving the old log file and optionally creating a new one

You can check other options for Ubuntu package on the link below:

http://manpages.ubuntu.com/manpages/xenial/man8/logrotate.8.html

Step 3: Wait until next day

On Ubuntu 16.04, no further actions are need because there is a cron job already running the logrotate daily, so your new file will be loaded on next day.

To confirm if the cron job is there, check the file:

/etc/cron.daily/logrotate

Check Logrotate status

You can check the logrotate status, remember, your new file should appear on the next day.

cat /var/lib/logrotate/status

One config, several files

Here is another example of file that rotate all log files inside a specific directory, often used by apps deployed with mina gem, but you can use the same concept in your environment.