Build Linux Images with Packer

Project Goals

This project’s goal is to build a variety of Linux OS Images using Packer with the QEMU/KVM. The focus is to build OS images for a corporate environment where disk layout and the installed packages are as identical as possible.

A secondary goal is to build images for both BIOS and UEFI machines, but the focus is clearly set on the UEFI bulids.

A strong focus is to keep the CODE as DRY as possible and to try to keep the actual configuration for each new release to a minimum.

To keep the post-processing as generic as possible Ansible is used. The Ansible code has been decoupled to keep it modular and replaceable.

Project Scope

Target Platforms

This repo contains the packer instructions to build images for the following platforms:

• QEMU (base image)

• VMware

• Hyper-V

• Azure

There are plans to also create images for:

• GCP (Google Compute Platform)

Supported Operating Systems

Full name	Build name
Red Hat Enterprise Linux 7	rhel_7
Red Hat Enterprise Linux 8	rhel_8
Red Hat Enterprise Linux 9	rhel_9
CentOS 7	centos_7
Rocky Linux 8	rocky_8
Rocky Linux 9	rocky_9
Oracle Linux 7	oraclelinux_7
Oracle Linux 8	oraclelinux_8
Oracle Linux 9	oraclelinux_8
SUSE Enterprise Linux 15.2	sle_15
Ubuntu 18.04 LTS	ubuntu_18.04
Ubuntu 20.04 LTS	ubuntu_20.04
Ubuntu 22.04 LTS	ubuntu_22.04

Features

• Can build both BIOS and UEFI based images.

• Uses single GPT partition layout for both builds.

• Same disklayout for all images.

• Installation of cloud-init packages.

• Conversion of QEMU qcow2 to Hyper-V (VHDX), Azure (VHD) and VMware (VMDK).

Dependencies

• Docker with container uroesch/docker-packer

or

• Packer

• Ansible

• Qemu with kernel extenstion KVM

• Ruby

• Rake

• jq

Howto

Build with docker

The docker container contains the and the corresponding docker-packer script setup a noVNC websocket which can be used to monitor the progress of the build.

If building one container at the time the URL for connectiong is http://localhost:11180/vnc.html?host=localhost&port=11180

If running on a seperate machine one may open an SSH tunnel to view the content with a browser.

Build all images

docker-packer rake

The disk images are stored in the directory images.

Build a specific OS

Consult the build name in the operating system table.

In this example only Centos 7 is built.

docker-packer rake BUILD=centos_7

Build only for a specific target

In this example only Ubuntu 20.04 for Azure is built.

ℹ️	Requires a qcow2 base image to be present in the images directory.

docker-packer rake BUILD=centos_7 ONLY="*.azure"

Build locally

Build all images headless

rake

The disk images are stored in the directory images.

Build image with QEMU window

rake HEADLESS=false

Build only a specific OS

rake BUILD=ubuntu_20.04

Build only for a specific target

ℹ️	Requires a qcow2 base image to be present in the images directory.

rake BUILD=centos_7 ONLY='*.vmware'

Build image with BIOS firmware

rake BUILD=centos_7 FIRMWARE=bios

More Documents

• Directory Structure

• Packer Files

• File Naming Convention

• Workflow

Build changes

All parameters are stored under the <os_name>.pkrvars.hcl files. e.g for CentOS 8 the file is called centos_8.pkrvars.hcl.

In the templates directory the kickstart, preseed and Cloud-Init templates are stored. The are ERB templates and use the config[] hash to refer to the variables defined in the packer variable files.

Some of the templates are symlinks to make changes for a certain of release global. E.g. the Centos 7, Red Hat Enterprise Linux 7 and Oracle Linux 7 share a common kickstart file.