Why does my CentOS logrotate run at random times?

I put a logrotate configuration file in /etc/logrotate.d/ and expected the logs to rotate at a consistent time; however, they do not... log rotation times are seemingly random +/- one hour.

Why are the log rotation start times random, and how can I change this?

/opt/backups/network/*.conf {
        copytruncate
        rotate 30
        daily
        create 644 root root
        dateext
        maxage 30
        missingok
        notifempty
        compress
        delaycompress
        postrotate
            ## Create symbolic links in daily/
            PATH=`/usr/bin/dirname $1`;
            FILE=`/bin/basename $1`;
            /bin/ln -s $1 $PATH/daily/$FILE
        endscript
}

The key is knowing that CentOS runs the scripts in /etc/cron.{daily,weekly,monthly} from anacron... /etc/anacrontab is setting RANDOM_DELAY, which does what you might expect (it delays up to RANDOM_DELAY minutes before starting the job)...

# /etc/anacrontab: configuration file for anacron

# See anacron(8) and anacrontab(5) for details.

SHELL=/bin/sh
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
# the maximal random delay added to the base delay of the jobs
RANDOM_DELAY=45
# the jobs will be started during the following hours only
START_HOURS_RANGE=3-22

#period in days   delay in minutes   job-identifier   command
1       5       cron.daily              nice run-parts /etc/cron.daily
7       25      cron.weekly             nice run-parts /etc/cron.weekly
@monthly 45     cron.monthly            nice run-parts /etc/cron.monthly

Setting RANDOM_DELAY=0 / START_HOURS_RANGE=3 fixed the problem...

EDIT

After further thought, I am going to remove anacron and install normal vixie cron...

Not the answer, but I recently was trying to figure this out for another reason and couldn't find any documentation on how Redhat 6, Centos, etc run cron. Here's what I reverse engineered:

1. crond still runs at system startup - it loads all files in /etc/cron.d
2. /etc/cron.d/0hourly runs all files in /etc/cron.hourly
3. /etc/cron.hourly/0anacron runs anacron
4. anacron loads /etc/anacrontab
5. /etc/anacrontab runs (via run-parts) /etc/cron.daily, /etc/cron.weekly and /etc/cron.monthly

So, it is more complicated than in previous versions.

It's possible to restore the old behavior by adding the hourly, weekly and monthly entries back into /etc/crontab (which is now empty), but anacrontab will need to be updated too. This may or may not break future updates...