20181205-bonusEn-logrotate.md

Bonus: logrotate to handle nginx logs

All nginx events are logged in "/opt/var/log/nginx/". As time goes by, error and access files get heavier and heavier. To avoid problems, it may be useful to use logrotate to replace logs according to predefined rules.

Installation

We're gonna use Entware to install logrotate:

opkg install logrotate

Configuration

The easiest way is to create a special configuration file for nginx logs in /opt/etc/logrotate.d/, so:

vi /opt/etc/logrotate.d/nginx

Text is inserted with "i" and saved with Esc and then":ZZ".
Here is my configuration:

/opt/var/log/nginx/access.log {
		prerotate
			nginx -s stop
		weekly
		rotate 4
		postrotate
			nginx -s start
		compress
		delaycompress
		missingok
		notifempty
		create 644
}

/opt/var/log/nginx/error.log {
		prerotate
			nginx -s stop
		weekly
		rotate 4
		postrotate
			nginx -s start
		compress
		delaycompress
		missingok
		notifempty
		create 644
}

My config stops nginx, rotates the logs, compresses them, then restarts nginx. For more information on configuration, refer to the man.

Setting up a cron job

In order for logrotate to be launched automatically on a regular basis, it is necessary to modify the services-start file:

vi /jffs/scripts/services-start

to add - at the end - the following line:

cru a "logrotate" '0 2 * * 1 logrotate /opt/etc/logrotate.d/nginx > /dev/null'

This line allows to launch logrotate every Monday at 2am, with the configuration present in /opt/etc/logrotate.d/nginx.