How to build custom images

Using packer, you can build custom, MAAS-deployable images for the following operating systems:

• RHEL 7
• RHEL 8
• CentOS 7
• Oracle Linux 8
• Oracle Linux 9
• VMware ESXi

You can also build deployment Windows images.

Build Linux images

Verify requirements

You need a machine running Ubuntu 18.04+ or 22.04+ with the ability to run KVM virtual machines. Ensure the following components are available:

Gather components

Collect packer, its dependencies and templates, and a suitable ISO file before starting.

Install Packer

Packer is the tool of choice for building custom MAAS images.

For Ubuntu 18.04+

sudo apt install packer

For Ubuntu 22.04+ (Required for Oracle Linux 8/9)

curl -fsSL https://apt.releases.hashicorp.com/gpg | sudo apt-key add -
sudo apt-add-repository "deb [arch=amd64] https://apt.releases.hashicorp.com $(lsb_release -cs) main"
sudo apt-get update && sudo apt-get install packer

Install dependencies

Install dependencies required for image building:

sudo apt install qemu-utils

For Oracle Linux 8/9 and VMware ESXi, install additional dependencies:

sudo apt install libnbd-bin nbdkit fuse2fs qemu-utils

For VMware ESXi, install Python pip:

sudo apt install pip

Get Packer templates

Clone the Packer templates repository:

git clone https://github.com/canonical/packer-maas.git

Download ISO files

Download the appropriate ISO for your desired OS version and place it in the corresponding subdirectory:

Customize the image

Modify the Kickstart file to customize the deployment image:

Refer to the respective Kickstart documentation for detailed customization options.

Configure a build proxy (optional)

To use a proxy during the build process:

1. Set the HTTP proxy:

   export HTTP_PROXY=http://your-proxy-server:port
   

2. Modify Kickstart Files:

   Add --proxy=$HTTP_PROXY to lines starting with url or repo.

For Oracle Linux 8/9, set the KS_PROXY variable:

export KS_PROXY=$HTTP_PROXY

Build the image

Using the makefile

Run the following command in the appropriate subdirectory (rhel7, rhel8, centos7, ol8, ol9, vmware-esxi):

make ISO=/PATH/TO/your-iso-file.iso

Manually, Using Packer

Alternatively, manually run Packer:

For RHEL 7/8:

sudo PACKER_LOG=1 packer build -var 'iso_path=/PATH/TO/your-iso-file.iso' rhel7.json  # or rhel8.json

For CentOS 7:

sudo PACKER_LOG=1 packer build centos7.json

For Oracle Linux 8/9:

packer init .
PACKER_LOG=1 packer build .

For VMware ESXi:

sudo PACKER_LOG=1 packer build -var 'vmware_esxi_iso_path=/PATH/TO/your-esxi-iso-file.iso' vmware-esxi.json

Note: Packer runs in headless mode by default. To view the installation output, connect via VNC or set headless to false.

Upload the image to MAAS

Commands for each OS

Verify and log in

Deploy the image and log in to verify customizations:

Build Windows images

Since Windows is a proprietary operating system, MAAS can’t download these images. You need to manually generate images to use with MAAS by using Windows ISO images. On the upside, the end result will be much simpler, since there are CLI and WebUI tools to upload a Windows image – which helps automate the process.

Verify prerequisites

To build the image:

• A machine running Ubuntu 18.04+ with the ability to run KVM virtual machines.
• qemu-utils, libnbd-bin, nbdkit and fuse2fs
• qemu-system
• ovmf
• cloud-image-utils
• Packer, v1.7.0 or newer
• A copy of the packer-maas git repository:

git clone https://github.com/canonical/packer-maas.git

Note that Ubuntu 22.04+ is required to build Windows 11 images due to swtpm (Software TPM) package requirements.

Supported Microsoft Windows versions

This process has been build and deployment tested with the following versions of Microsoft Windows:

• Windows Server 2025
• Windows Server 2022
• Windows Server 2019
• Windows Server 2016
• Windows 10 PRO+
• Windows 11 PRO+

To deploy the image:

• MAAS 3.2+
• Curtin 21.0+

Gather components

Collect an ISO image and a template before trying to build a Windows image.

Get the windows.pkr.hcl Template

This template builds a dd.tgz MAAS image from an official Microsoft Windows ISO/VHDX.
This process also installs the latest VirtIO drivers as well as Cloudbase-init.

Obtain Microsoft Windows ISO images

You can obtains Microsoft Windows Evaluation ISO/VHDX images from the following links:

• Windows Server 2025
• Windows Server 2022
• Windows Server 2019
• Windows Server 2016
• Windows 10 Enterprise
• Windows 11 Enterprise

Build the image

The build the image you give the template a script which has all the customization:

sudo make windows ISO=<path-to-iso> VERSION=<windows-version>

Example:

sudo make ISO=/mnt/iso/Windows_Server_2025_SERVER_EVAL_x64FRE_en-us.iso VERSION=2025

Adjust makefile parameters

EDIT

The edition of a targeted ISO image. It defaults to PRO for Microsoft Windows 10/11 and SERVERSTANDARD for Microsoft Windows Servers. Many Microsoft Windows Server ISO images do contain multiple editions and this parameter is useful to build a particular edition such as Standard or Datacenter etc.

HEADLESS

Whether VNC viewer should not be launched. Default is set to false. This is useful when building images on machines that do not have graphical libraries such as SDL/GTK installed. Headless mode does include an open VNC port to monitor the build process if needed.

ISO

Path to Microsoft Windows ISO image used to build the MAAS image.

PACKER_LOG

Enable (1) or Disable (0) verbose packer logs. The default value is set to 0.

PKEY

User supplied Microsoft Windows Product Key. When using KMS, you can obtain the activation keys from the link below:

• KMS Client Activation and Product Keys

Please note that PKEY is an optional parameter but it might be required during the build time depending on the type of ISO being used. Evaluation series ISO images usually do not require a product key to proceed, however this is not true with Enterprise and Retail ISO images.

TIMEOUT

Defaults to 1h. Supports variables in h (hour) and m (Minutes).

VHDX

Path to Microsoft Windows VHDX image used to build the image.

VERSION

Specify the Microsoft Windows Version. Example inputs include: 2025, 2022, 2019, 2016, 10 and 11. Currently defaults to 2022.

Upload Windows images to MAAS

Use MAAS CLI to upload the image:

maas admin boot-resources create \
    name='windows/windows-server' \
    title='Windows Server' \
    architecture='amd64/generic' \
    filetype='ddtgz' \
    content@=windows-server-amd64-root-dd.gz

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Last updated 16 days ago.