Chapter 6. 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 .tar file that has 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 a root file system. To create the ISO image, select the image type image-installer. Image builder builds a .tar file with the following content:

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

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

6.1. Creating a boot ISO installer image using the image builder in the command-line interface

You can create a customized boot ISO installer image by 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-installer 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 might 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. After the compose is finished, download the created image file:

    # composer-cli compose image UUID

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

    As a result, image builder builds a .iso file that contains a .tar file. The .tar file is the image that will be installed for the Operating system. The . iso is set up to boot Anaconda and install the tar file to set up the system.


  1. Navigate to the folder where you downloaded the image file.
  2. Locate the .iso image you downloaded.
  3. Mount the ISO.

    $ mount -o ro path_to_ISO /mnt

    You can find the .tar file at the /mnt/liveimg.tar.gz directory.

  4. Extract .tar file content.

    $ tar xzf /mnt/liveimg.tar.gz

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

6.2. Creating a boot ISO installer image using image builder in the GUI

You can build a customized boot ISO installer image using image builder GUI.



  1. Open the image builder interface of the RHEL web console in a browser. See Creating an image builder blueprint using the command-line interface.
  2. Locate the blueprint that you want to use to build your image. To do so, enter the blueprint name or a part of it into the search box at upper left, and click Enter.
  3. On the right side of the blueprint, click the corresponding Create Image button.

    The Create image dialog wizard opens.

  4. On the Create image dialog wizard:

    1. In the Image Type list, select "RHEL Installer (.iso)".
    2. Click Create.

Image builder adds the compose of a RHEL ISO image to the queue.


The image build process takes a few minutes to complete.

After the process is complete, you can see the image build complete status. Image builder creates the ISO image.


After the image is successfully created, you can download it.

  1. Click Download to save the "RHEL Installer (.iso)" image to your system.
  2. Navigate to the folder where you downloaded the "RHEL Installer (.iso)" image.
  3. Locate the .tar image you downloaded.
  4. Extract the "RHEL Installer (.iso)" image content.

    $ tar -xf content.tar

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

6.3. Installing an image builder ISO image to a bare metal system

Install the bootable ISO image you created by using image builder to a bare metal system.



  1. Write the bootable ISO image directly to the USB drive using the dd tool. For example:

    dd if=installer.iso of=/dev/sdX

    Where installer.iso is the ISO image file name and /dev/sdX is your USB flash drive device path.

  2. Insert the flash drive into a USB port of the computer you want to boot.
  3. Boot the ISO image from the USB flash drive.

    When the installation environment starts, you might need to complete the installation manually, similarly to the default Red Hat Enterprise Linux installation.