Setting up proper logging today prevents the big headache tommorow

Components

• syslog - inbuilt drupal module to log drupal errors(no particular reason for choosing this module, can use any appropriate module that logs to file or write a module that implements hook_watchdog)
• logrotate - to archive the old logs to help classify by data and save space.

Steps

1. We enable syslog in the modules in drupal and save with the default config
2. add a file in /etc/rsyslog.d directory called 45-drupal.conf for drupal log specific configuration
3. add this to file

local0.* /var/log/drupal.log
& ~

4. restart rsyslog by running sudo service rsyslog restart
5. Write a configuration file in /etc/logrotate.d/

/var/log/drupal.log {
daily
missingok
rotate 31
compress
notifempty
copytruncate
sharedscripts
}