CentOS - Jun 2018 - Questions about yum-cron

Hi,

Up until now I always kept my servers up-to-date manually. Currently I'm
experimenting with yum-cron to automate this process.

I read through various online tutorials, and now I have a couple questions.

1. As far as I know, when editing /etc/yum/yum-cron.conf, I can only use
the following value for update_cmd :

  update_cmd = default

If I understand this correctly, 'update_cmd = security' would have no
effect, since contrary to RHEL, CentOS doesn't provide the necessary
metadata to operate the distinction between security updates and other
updates like mere bugfixes. Please correct me if I'm wrong.

2. It looks like editing /etc/yum/yum-cron.conf affects a *daily*
operation of yum-cron, whereas editing /etc/yum/yum-cron-
hourly.conf provides hourly operations. The documentation is not very
clear about this, and I'm a little confused here. In other words,
yum-cron.conf affects /etc/cron.daily/0yum-daily.cron, and
yum-cron-hourly.conf affects /etc/cron.hourly/0yum-hourly.cron.

I only really need yum-cron to run once a day, which would be
sufficient. That being said, I can't figure out at what time it
launches. All my users are in France, so ideally the daily yum-cron
should be launched somewhere between 04:00 and 05:00 AM, since updating
a package like httpd would restart the corresponding processes and kick
online users out. I can't seem to figure out a way to define the exact
time at which the daily yum-cron is being launched, since this doesn't
seem to be controlled by standard crontab.

Any suggestions ?

Niki

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> 
> 2. It looks like editing /etc/yum/yum-cron.conf affects a *daily*
> operation of yum-cron, whereas editing /etc/yum/yum-cron-
> hourly.conf provides hourly operations. The documentation is not very
> clear about this, and I'm a little confused here. In other words,
> yum-cron.conf affects /etc/cron.daily/0yum-daily.cron, and
> yum-cron-hourly.conf affects /etc/cron.hourly/0yum-hourly.cron.
Yes. All the cron scripts do is to execute yum-cron with an optional
config script as an argument; if no config file is given, it uses the
default (/etc/yum/yum-cron.conf). 'man yum-cron' tells you this.
> 
> I only really need yum-cron to run once a day, which would be
> sufficient.
The hourly version (in the default install) does nothing other than
update the caches.

>  That being said, I can't figure out at what time it
> launches. All my users are in France, so ideally the daily yum-cron
> should be launched somewhere between 04:00 and 05:00 AM, since updating
> a package like httpd would restart the corresponding processes and kick
> online users out. I can't seem to figure out a way to define the exact
> time at which the daily yum-cron is being launched, since this doesn't
> seem to be controlled by standard crontab.
The scripts in /etc/cron.daily are run via anacron with a configuration
 file of /etc/anacrontab. The exact time the jobs are run are not
specified and are variable depending on what the machine is doing (and
a random delay). But you can impose time limits on when the jobs can be
executed.

cron.hourly is different and executed via the normal cron system
(config is in /etc/cron.d/0hourly)

P.