Posts tagged CentOS

Create a bootable ISO with kickstart

Installing Linux on a physical or virtual machine can be fun for a couple of time, but configuring a system can be combursome after a couple of times. Red Hat developed Kickstart to install and configure machines via the network, but also as part of an ISO file that can used in a virtual CD-ROM drive or on a bootable USB-drive.

The following steps are required to create a bootable ISO file with a kickstart file and when the ISO file is booted, the kickstart file is used to install and configure the system. Creating a bootable ISO file is not a difficult task, but it is a manual procedure. The following steps are required to create a bootable ISO file with a kickstart file.

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Using YUM history to see package changes

When you install or update packages on your system, then changes may occur that were not expected. Recent security updates on a server and left Nagios in a failed state, but what exactly happened, and can it be traced back as yum-cron installs all required security updates? Luckily YUM keeps a history database of all actions and with yum history can you list all transactions.

As transaction 15 was the latest and only transaction before the defect occurred it is the one to look into. With yum history info the details of the transaction can be shown. It shows when and who triggered the transaction, but also with which version of RPM, YUM, and which plugins for YUM were used. Most importantly it also shows which package was updated with versions used and from which repository. This narrows the search down to the packages shown as updated and sees what they changed on the system.

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Upgrading from CentOS 7.3 to 7.4

Last month CentOS 7.4 was announced and it was time to rebuild some servers from scratch to make sure all playbooks were still correct as it is always good to know you can quickly (re)build servers when needed. For some other servers, the impact would be big due to huge amounts of data that needed to be moved around and an in-place upgrade would be sufficient.

Upgrading is very straightforward as it the same as the update option with “-obsoletes” flag set which removes obsolete packages. So let start with CentOS 7.3.

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