Chapter 7. Creating a boot ISO installer image with Image Builder

You can use Image Builder to create bootable ISO Installer images. These images consist of a tarball that contains a root file system. You can use the bootable ISO image to install the file system to a bare metal server.

Image Builder builds a manifest that creates a boot ISO that contains the commit and a root file system. To create the ISO image, choose the new image type image-installer. Image Builder builds a .tar file, which contains:

  • a standard Anaconda installer ISO
  • an embedded RHEL system tarball
  • a default kickstart file that installs the commit with minimal default requirements

The created installer ISO image embeds a pre-configured system image that you can install directly to a bare metal server.

7.1. Creating a boot ISO installer image with Image Builder in the command-line interface

This procedure shows how to build a custom boot ISO installer image using the Image Builder command-line interface.



  1. Create the ISO image:

    # composer-cli compose start BLUEPRINT-NAME image-installer
    • BLUEPRINT-NAME with name of the blueprint you created
    • IMAGE-TYPE is the image type

      The compose process starts in the background and the UUID of the compose is shown.

  2. Wait until the compose is finished. Note that this may take several minutes.

    To check the status of the compose:

    # composer-cli compose status

    A finished compose shows a status value of FINISHED. Identify the compose in the list by its UUID.

  3. Once the compose is finished, download the resulting image file:

    # composer-cli compose image UUID

    Replace UUID with the UUID value shown in the previous steps.

    As a result, Image Builder builds a .tar file thta contains the ISO Installer image.


  1. Navigate to the folder where you downloaded the image file.
  2. Locate the .tar image you downloaded.
  3. Extract the .tar content.

You can use the resulting ISO image file on a hard drive or to boot in a virtual machine, for example, in an HTTP Boot or a USB installation.

7.2. Installing the ISO image to a bare metal system

This procedure shows how to install the bootable ISO image you created by using Image Builder to a bare metal system, using the command-line interface.


  • You created the bootable ISO image using Image Builder.
  • You have downloaded and extracted the bootable ISO image.
  • You have a 8 GB USB flash drive.


    The ISO size can be bigger depending on the packages that the you selected in your blueprint.


  1. Place the bootable ISO image file on a USB flash drive.
  2. Connect the USB flash drive to the port of the computer you want to boot.
  3. Boot the ISO image from the USB flash drive.
  4. Perform the steps to install the customized bootable ISO image.

    The boot screen shows you the following options:

    • Install Red Hat Enterprise Linux 9
    • Test this media & install Red Hat Enterprise Linux 9

Additional resources