In EL7, we can use yum-cron to automatically install updates. On EL8, the equivalent tool is dnf-automatic. Here is how to set it up.
Install the package
dnf -y install dnf-automatic
Edit the config
Edit /etc/dnf/automatic.conf. It is quite similar to yum-cron config. Some of the important parameters are:
upgrade_type = default # default: all updates; security: security updates only
apply_updates = yes # no: do not apply the updates
If you want to receive email notification, edit the section under [emitters]
Finally, enable the systemd timer
systemctl enable --now dnf-automatic.timer
By default, this timer runs the job daily at 0600, plus a random delay. To see when the next run is scheduled at, run this
[[email protected] ~]# systemctl list-timers dnf-automatic.timer
NEXT LEFT LAST PASSED UNIT ACTIVATES
Tue 2021-07-13 06:23:05 HKT 13h left n/a n/a dnf-automatic.timer dnf-automatic.service
Occasionally, look for processes that require restarting after update.
dnf needs-restarting
If you configure email emitter, you will receive an email whenever an update is downloaded.
The following updates were downloaded on 'rock.one27.lab':
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Package Architecture Version Repository Size
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Upgrading:
rocky-gpg-keys noarch 8.4-30.el8 baseos 11 k
rocky-release noarch 8.4-30.el8 baseos 20 k
rocky-repos noarch 8.4-30.el8 baseos 13 k
Transaction Summary
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Upgrade 3 Packages 
