Chapter 3. Distribution of content in RHEL 8

3.1. Installation

Red Hat Enterprise Linux 8 can be installed using ISO images. Two basic types of installation media are available for the AMD64 and Intel 64 (x86_64), ARM (aarch64), IBM POWER Systems, Little Endian (ppc64le), and IBM Z (s390x) architectures:

  • Binary DVD - A full installation image, which can be used to boot the installation program and perform an entire installation without additional package content sets.
  • Netinstall DVD (boot.iso) - A minimal boot image, which can be used to boot into the installation program. This option requires access to a local or remote repository providing additional packages.

The document, Installing and Deploying RHEL, provides instructions for using these ISO images to create bootable media.

3.2. Repositories

Red Hat Enterprise Linux 8 is distributed through two repositories:

  • BaseOS
  • AppStream

Both content sets are required for a basic RHEL installation, and are available with all RHEL subscriptions.

Content in the BaseOS repository is intended to provide the core set of the underlying OS functionality that provides the foundation for all installations. This content is available in the RPM format and is subject to support terms similar to those in previous releases of RHEL. For a list of packages distributed through BaseOS, see Appendix B, Packages in BaseOS.

Content in the AppStream repository includes additional user space applications, runtime languages, and databases in support of the varied workloads and use cases. Content in AppStream is available in one of two formats - the familiar RPM format and an extension to the RPM format called modules. For a list of packages available in AppStream, see Appendix C, Packages in AppStream.

3.3. Application Streams

Red Hat Enterprise Linux 8.0 introduces the concept of Application Streams. Multiple versions of user space components are now delivered and updated more frequently than the core operating system packages. This provides greater flexibility to customize Red Hat Enterprise Linux without impacting the underlying stability of the platform or specific deployments.

Components made available as Application Streams can be packaged as modules or RPM packages and are delivered through the AppStream repository in RHEL 8.

Modules are collections of packages representing a logical unit: an application, a language stack, a database, or a set of tools. These packages are built, tested, and released together.

Module streams represent versions of the Application Stream components. For example, two streams (versions) of the PostgreSQL database server are available in the postgresql module: PostgreSQL 10 (the default stream) and PostgreSQL 9.6. Only one module stream can be installed on the system. Different versions can be used in separate containers.

Detailed module commands are described in the Using Application Stream document. For a list of modules available in AppStream, see Appendix A, Modules available in RHEL 8.0 Beta.