Thursday, 20 September 2018

Changing Apache log rotation behaviour on CentOS / RHEL

On a default install of CentOS or Red Hat Enterprise Linux, the log rotation script will automatically rotate the Apache log file each day and then reload the httpd service. This post looks at how to prevent this action from occuring automatically, or to change the behaviour to rotate the log files if your naming convention for log files is different from the default.
The cron daemon on a CentOS or Red Hat Enterprise Linux server by default runs the scripts in the directory /etc/cron.daily on a daily basis. This includes running the "logrotate" script which runs /usr/sbin/logrotate passing it the /etc/logrotate.conf configuration file. The default version of this logrotate.conf file is as follows:
# see "man logrotate" for details
# rotate log files weekly
weekly

# keep 4 weeks worth of backlogs
rotate 4



# create new (empty) log files after rotating old ones
create


# uncomment this if you want your log files compressed
#compress


# RPM packages drop log rotation information into this directory
include /etc/logrotate.d


# no packages own wtmp -- we'll rotate them here
/var/log/wtmp {
    monthly
    minsize 1M
    create 0664 root utmp
    rotate 1
}


# system-specific logs may be also be configured here.
These default variables are fairly straight forward and give you control over how frequently the log files are rotated, how many lots of previous log files to keep before deleting them, whether or not to compress them and so on. It also tells logrotate to process all the files in the directory /etc/logrotate.d
The file which controls log rotation of Apache on CentOS and Red Hat Enterprise Linux is named /etc/logrotate.d/httpd, and the default contents of this file are as follows:
/var/log/httpd/*log {
    missingok
    notifempty
    sharedscripts
    postrotate
        /sbin/service httpd reload > /dev/null 2>/dev/null || true
    endscript
}
What this file is saying, is to rotate all files that match the pattern /var/log/httpd/*.log. The default access and error log files in Apache on CentOS and RHEL are named "access_log" and "error_log" so they match this pattern.
If you have changed the default names of the log files and they don't match this pattern, then you can have logrotate rotate your log files by making sure the pattern is in this file in place of the /var/log/httpd/*.log line. For example, if your log files were named error.foo and access.foo then /var/log/httpd/*.foo would match them.
If you do not wish the logrotate script to rotate your Apache log files at all, then you can simply delete this file like so, logged in either as root or using sudo:
rm -f /etc/logrotate.d/httpd
The changes will take effect the next time the logrotate script is run.

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