Menu Close
Settings Close

Language and Page Formatting Options

Red Hat Training

A Red Hat training course is available for RHEL 8

Chapter 1. Image builder description

To deploy a system on a cloud platform, create a system image. To create RHEL images, RHEL 8 use the image builder tool.

1.1. What is image builder?

You can use image builder to create customized system images of RHEL, including system images prepared for deployment on cloud platforms. Image builder automatically handles the setup details for each output type and is therefore easier to use and faster to work with than manual methods of image creation. You can access the image builder functionality through a command-line interface in the composer-cli tool, or a graphical user interface in the RHEL web console.

Note

From RHEL 8.3 onward, the osbuild-composer back end replaces lorax-composer. The new service provides REST APIs for image building.

1.2. Image Builder terminology

Blueprint

A blueprint is a description of a customized system image. It lists the packages and customizations that will be part of the system. You can edit blueprints with customizations and save them as a particular version. When you create a system image from a blueprint, the image is associated with the blueprint in the image builder interface of the RHEL web console.

You can create blueprints in the TOML format.

Compose
Composes are individual builds of a system image, based on a specific version of a particular blueprint. Compose as a term refers to the system image, the logs from its creation, inputs, metadata, and the process itself.
Customizations
Customizations are specifications for the image that are not packages. This includes users, groups, and SSH keys.

1.3. Image builder output formats

Image builder can create images in multiple output formats shown in the following table. To check the supported types, run the command:

# composer-cli compose types

Table 1.1. Image builder output formats

DescriptionCLI namefile extension

QEMU QCOW2 Image

qcow2

.qcow2

TAR Archive

tar

.tar

Amazon Machine Image Disk

ami

.raw

Azure Disk Image

vhd

.vhd

Google Cloud Platform

gce

.vhd

VMware Virtual Machine Disk

vmdk

.vmdk

Openstack

openstack

.qcow2

RHEL for Edge Commit

edge-commit

.tar

RHEL for Edge Container

edge-container

.tar

RHEL for Edge Installer

edge-installer

.iso

RHEL for Edge Raw

edge-raw-image

.tar

RHEL for Edge Simplified Installer

edge-simplified-installer

.iso

ISO image

image-installer

.iso

1.4. Image builder system requirements

The environment where image builder runs, for example a dedicated virtual machine, must meet requirements listed in the following table.

Table 1.2. Image builder system requirements

ParameterMinimal Required Value

System type

A dedicated virtual machine

Processor

2 cores

Memory

4 GiB

Disk space

20 GiB of free space in the /var filesystem

Access privileges

Administrator level (root)

Network

Internet connectivity

Note

If you do not have internet connectivity, you can use image builder in isolated networks if you reconfigure it to not connect to Red Hat Content Delivery Network (CDN). For that, you must override the default repositories to point to your local repositories. Ensure that you have the your content mirrored internally or use Red Hat Satellite. See Managing repositories for more details.