Chapter 6. Installer and image creation

The Open Security Content Automation Protocol (OSCAP) add-on is enabled by default in RHEL 8.

The Kdump add-on adds support for configuring kernel crash dumping during installation. This add-on has full support in Kickstart (using the %addon com_redhat_kdump command and its options), and is fully integrated as an additional window in the graphical and text-based user interfaces.

The default size of the /boot partition in the RHEL installers remains 1 GB. However, this size might be insufficient for systems that generate larger initramfs images, particularly in environments that include additional drivers or firmware components. When planning a migration or upgrade, provision the /boot partition with at least 2 GB to reduce the risk of running out of space during future kernel updates.

To ensure a smooth upgrade experience, consider the following:

This change helps accommodate growing initramfs sizes and supports more reliable system updates.

Since Red Hat Enterprise Linux 8.2, you can register your system, attach RHEL subscriptions, and install from the Red Hat Content Delivery Network (CDN) before package installation. Interactive GUI installations, as well as automated Kickstart installations, support this feature. For more information, see the RHEL 8.2 Release Notes document.

Red Hat Lightspeed is a managed service that gathers and analyzes platform and application data to predict risk, recommend actions, and track costs. Red Hat Lightspeed alerts you about warnings or optimizations that are relevant to several operational areas: system availability (including potential outages), security (for example, a new CVE is discovered for your systems), and business (such as overspending). Red Hat Lightspeed is included as part of your Red Hat subscription and is accessible through the Red Hat Hybrid Cloud Console. See also the Red Hat Lightspeed documentation.

Since Red Hat Enterprise Linux 8.2, you can register your system to Red Hat Lightspeed during installation. Interactive GUI installations, as well as automated Kickstart installations, support this feature. For more information, see the RHEL 8.2 Release Notes document.

In Red Hat Enterprise Linux 8, a unified ISO automatically loads the BaseOS and AppStream installation source repositories. This feature works for the first base repository that is loaded during installation. For example, if you boot the installation with no repository configured and have the unified ISO as the base repository in the graphical user interface (GUI), or if you boot the installation using the inst.repo= option that points to the unified ISO.

As a result, the AppStream repository is enabled under the Additional Repositories section of the Installation Source GUI window. You cannot remove the AppStream repository or change its settings but you can disable it in Installation Source. This feature does not work if you boot the installation using a different base repository and then change it to the unified ISO. If you do that, the base repository is replaced. However, the AppStream repository is not replaced and points to the original file.

In Red Hat Enterprise Linux 8, multiple network locations of stage2 or Kickstart files can be specified to prevent installation failure. This update enables the specification of multiple inst.stage2 and inst.ks boot options with network locations of stage2 and a Kickstart file. This avoids the situation in which the requested files cannot be reached and the installation fails because the contacted server with the stage2 or the Kickstart file is inaccessible.

With this new update, the installation failure can be avoided if multiple locations are specified. If all the defined locations are URLs, namely HTTP, HTTPS, or FTP, they will be tried sequentially until the requested file is fetched successfully. If there is a location that is not a URL, only the last specified location is tried. The remaining locations are ignored.

Previously, you could only specify a base repository from the kernel boot parameters. In Red Hat Enterprise Linux 8, a new kernel parameter, inst.addrepo=<name>,<url>, allows you to specify an additional repository during installation. This parameter has two mandatory values: the name of the repository and the URL that points to the repository. For more information, see the inst-addrepo usage.

Red Hat Enterprise Linux 8 supports installing from a repository on a local hard drive. Previously, the only installation method from a hard drive was using an ISO image as the installation source. However, the Red Hat Enterprise Linux 8 ISO image might be too big for some file systems; for example, the FAT32 file system cannot store files larger than 4 GiB. In Red Hat Enterprise Linux 8, you can enable installation from a repository on a local hard drive; you only need to specify the directory instead of the ISO image. For example: inst.repo=hd:<device>:<path to the repository>.

For more information about the Red Hat Enterprise Linux 8 BaseOS and AppStream repositories, see the Repositories section of this document.

The Installation Summary window of the Red Hat Enterprise Linux 8 graphical installation has been updated to a new three-column layout that provides improved organization of graphical installation settings.

Previously, the Red Hat Enterprise Linux installation program did not provide system purpose information to Subscription Manager. In Red Hat Enterprise Linux 8, you can set the intended purpose of the system during a graphical installation by using the System Purpose window, or in a Kickstart configuration file by using the syspurpose command. When you set a system’s purpose, the entitlement server receives information that helps auto-attach a subscription that satisfies the intended use of the system.

Previously, it was not possible for the pykickstart library to provide system purpose information to Subscription Manager. In Red Hat Enterprise Linux 8, pykickstart parses the new syspurpose command and records the intended purpose of the system during automated and partially-automated installation. The information is then passed to the installation program, saved on the newly-installed system, and available for Subscription Manager when subscribing the system.

In Red Hat Enterprise Linux 8, the installation program has been extended to handle all modular features. Kickstart scripts can now enable module and stream combinations, install module profiles, and install modular packages.

The following Kickstart commands and options have been deprecated in Red Hat Enterprise Linux 8.

Where only specific options are listed, the base command and its other options are still available and not deprecated.

Except the auth or authconfig command, using the commands in Kickstart files prints a warning in the logs.

You can turn the deprecated command warnings into errors with the inst.ksstrict boot option, except for the auth or authconfig command.

The following Kickstart commands and options have been completely removed in Red Hat Enterprise Linux 8. Using them in Kickstart files will cause an error.

Where only specific options and values are listed, the base command and its other options are still available and not removed.

The Image Builder tool enables users to create customized RHEL images. As of Red Hat Enterprise Linux 8.3, Image Builder runs as a system service osbuild-composer package.

With Image Builder, users can create custom system images which include additional packages. Image Builder functionality can be accessed through:

Image Builder output formats include, among others:

To learn more about Image Builder, see the documentation title Composing a customized RHEL system image.