I am a huge fan of automation in the home lab and have long had pipelines running that automate deployments of virtual machines in my VMware vSphere and now Proxmox environments. Ubuntu Server has been a staple “general” Linux operating system in my home lab for years. It is a great one to automate using Hashicorp Packer. In this post, I want to walk through how I am automating the newly released Ubuntu 26.04 builds in Proxmox VE using HashiCorp Packer. I will cover what Ubuntu 26.04 brings to the table and the files you need for Packer.
Why Ubuntu 26.04 LTS matters for home labs
Every new LTS release from Canonical is a big deal, especially for home lab environments. The LTS releases are typically what most of us run for our “production” workloads where stability and and long-term support matter.
Ubuntu 26.04 LTS, also known as Resolute Raccoon. Ubuntu Server continues the trend of providing a solid, enterprise-ready Linux platform while bringing in modern improvements under the hood. One of the biggest advantages of sticking with an LTS release is the extended support window. You get five years of standard support. This makes it ideal for infrastructure workloads that you do not want to constantly rebuild.
Under the hood, Ubuntu 26.04 includes a newer Linux kernel (7.0) that improves hardware compatibility, performance, and security. I think this is a great detail to know especially if you are running newer hardware in your home lab like Mini PCs, NVMe storage, or high-speed networking, or GPUs. Better driver support and kernel improvements can benefit and impact performance and stability in virtualized environments.
Another area of improvement with Ubuntu Server 26.04 is security. It contains updated cryptographic libraries, improved default configurations, and enhancements to things like AppArmor. If you don’t remember, this is the platform that continues to harden by default. For home labbers who are exposing services or experimenting with zero trust networking, this is an important detail.
You also benefit from updated package versions across the board. This means you get newer versions of Docker, Kubernetes components, development tools, and system utilities. Also, when it comes to automation, Ubuntu continues with this release to improve cloud-init and autoinstall capabilities. This is a great reason why using Ubuntu Server with Packer works so well.
Stop installing your Ubuntu Server VMs manually
For a long time, I was like many in the home lab or production environments. I installed the operating system the traditional “click ops” way. You mount the ISO, boot the VM, click through the installer, configure your networking, storage, install updates, etc, etc. Then when you were done, you converted this virtual machine into a “template” that you could reuse over and over.
This process works, but it is slow and inconsistent. Every time you install a VM manually, you can introduce slight differences. Maybe you forget a package. Maybe you configure something slightly different one time vs another. Maybe you use a different hostname pattern. Over time, these little differences add up and make your environment harder to manage.
The bigger issue though I think is time. Even a fast manual install still takes several minutes of hands-on work. Multiply that across multiple VMs and rebuilds, and this can lead to hours of total time over the course of a few weeks or months. This is where automation changes everything.
With Hashicorp Packer, you define your build once and reuse it forever. Every VM starts from the same known good state. If you need to update something, you update the template and rebuild. This leads to no more guessing what changed between your systems. In my home lab, this approach has allowed me to rebuild entire environments in a fraction of the time it used to take.
Haven’t heard of Hashicorp Packer?
If you haven’t that is ok, but you are missing out on one of the best tools for automating these types of operations that is out there. Packer is a tool that is specifically designed to create “machine images”. So, instead of you going through the motions of installing operating systems by hand, Packer handles the entire process for you.
So, at a high level, it gives you the following:
- Packer connects to Proxmox using the API
- It creates a new virtual machine
- It boots the VM using the Ubuntu 26.04 ISO
- It feeds automated install instructions using autoinstall and cloud-init
- It provisions the system with any additional configuration
- It converts the finished VM into a reusable template
In the end, you are left with a clean, fully configured Ubuntu 26.04 template that you can start cloning instantly. This approach is really powerful because it is repeatable and you can even schedule it to happen in the middle of the night if you want to.
Download Packer and Ubuntu 26.04
Packer is only just a quick download to get started. What I like about all the Hashicorp tools is they are all a self-contained binary that you run, including Packer. When you download Packer you are downloading the binary that is ready to run once you extract the zip file.
You can get Packer for your platform from this URL: Install | Packer.
Also, you need to download Ubuntu Server 26.04, which you can do from here: Get Ubuntu Server. Upload the .ISO image to your ISOs location in Proxmox which you will reference in your Packer files.
My Ubuntu 26.04 Packer template for Proxmox
Once you have Packer downloaded, it is just a matter of putting together the files you need to run the packer build. In a simple build, it requires the following files and structure:
- ubuntu-26.04.pkr.hcl
- variables.pkr.hcl
- 99-pve.cfg
- folder: http
- meta-data
- user-data
So, let’s see the contents of each of these. First we have the ubuntu-26.04.pkr.hcl file:
# Ubuntu Server Resolute Raccoon
# ---
# Packer Template to create an Ubuntu Server 26.04 LTS (Resolute Raccoon) on Proxmox
# Resource Definiation for the VM Template
packer {
required_plugins {
name = {
version = "~> 1"
source = "github.com/hashicorp/proxmox"
}
}
}
source "proxmox-iso" "ubuntu-server-resolute-raccoon" {
# Proxmox Connection Settings
proxmox_url = "${var.proxmox_api_url}"
username = "${var.proxmox_api_token_id}"
token = "${var.proxmox_api_token_secret}"
# (Optional) Skip TLS Verification
insecure_skip_tls_verify = true
# VM General Settings
node = "pvehost01"
vm_id = "299"
vm_name = "ubuntu-server-resolute-raccoon"
template_description = "Resolute Raccoon"
# VM OS Settings
boot_iso {
iso_file = "cephfs:iso/ubuntu-26.04-live-server-amd64.iso"
iso_storage_pool = "cephfs"
}
# (Option 2) Download ISO
# boot_iso {
# iso_url = "https://releases.ubuntu.com/26.04/ubuntu-26.04-live-server-amd64.iso"
# iso_checksum = "dec49008a71f6098d0bcfc822021f4d042d5f2db279e4d75bdd981304f1ca5d9"
# }
template_name = "packer-ubuntu2604"
# VM System Settings
qemu_agent = true
# VM Hard Disk Settings
scsi_controller = "virtio-scsi-pci"
disks {
disk_size = "80G"
format = "raw"
storage_pool = "rbd-vm"
type = "virtio"
}
# VM CPU Settings
cores = "4"
# VM Memory Settings
memory = "4096"
# VM Network Settings
network_adapters {
model = "virtio"
bridge = "vmbr0"
firewall = "false"
}
# VM Cloud-Init Settings
cloud_init = true
cloud_init_storage_pool = "local-lvm"
# PACKER Boot Commands
boot_command = [
"<esc><wait>",
"e<wait>",
"<down><down><down><end>",
"<bs><bs><bs><bs><wait>",
"autoinstall ds=nocloud-net\\;s=http://{{ .HTTPIP }}:{{ .HTTPPort }}/ ---<wait>",
"<f10><wait>"
]
boot = "c"
boot_wait = "5s"
# PACKER Autoinstall Settings
http_directory = "http"
http_bind_address = "${var.http_ip}"
# (Optional) Bind IP Address and Port
# http_port_min = 8802
# http_port_max = 8802
ssh_username = "ubuntu"
# (Option 1) Add your Password here
ssh_password = "ubuntu"
# - or -
# (Option 2) Add your Private SSH KEY file here
# ssh_private_key_file = "~/.ssh/id_rsa"
# Raise the timeout, when installation takes longer
ssh_timeout = "20m"
}
# Build Definition to create the VM Template
build {
name = "ubuntu-server-resolute-raccoon"
sources = ["proxmox-iso.ubuntu-server-resolute-raccoon"]
# Provisioning the VM Template for Cloud-Init Integration in Proxmox #1
provisioner "shell" {
inline = [
"while [ ! -f /var/lib/cloud/instance/boot-finished ]; do echo 'Waiting for cloud-init...'; sleep 1; done",
"sudo rm /etc/ssh/ssh_host_*",
"sudo truncate -s 0 /etc/machine-id",
"sudo apt -y autoremove --purge",
"sudo apt -y clean",
"sudo apt -y autoclean",
"sudo cloud-init clean",
"sudo rm -f /etc/cloud/cloud.cfg.d/subiquity-disable-cloudinit-networking.cfg",
"sudo rm -f /etc/netplan/00-installer-config.yaml",
"sudo sync"
]
}
}Next, is the variables.pkr.hcl file. Be sure to replace your proxmox_api_url, proxmox_api_token_id, and proxmox_api_token_secret with your own values.
***Note*** It would be best practice here to also create a variables.tfvars file and instead put sensitive variables in that file and add this to your .gitignore file. However, note for simplicity, just showing this in a single variables.pkr.hcl file. Replace with your values here:
variable "proxmox_api_url" {
type = string
default = "https://pvehost01.cloud.local:8006/api2/json"
}
variable "proxmox_api_token_id" {
type = string
default = "cicd@pam!cicd"
}
variable "proxmox_api_token_secret" {
type = string
default = "aaaa1111-bbbb-cccc-1111-aaaa1111bbbb"
sensitive = true
}
variable "http_ip" {
type = string
default = "10.1.149.27" #Needed if you have multiple IPs on your packer machine or need to hard set the IP it will connect to for the Packer server
description = "IP address to bind the HTTP server for cloud-init"
}Next, is the 99-pve.cfg file:
datasource_list: [ConfigDrive, NoCloud]Finally, we have the two files that are found in the http folder. First is the meta-data file. It is simple as it is blank. Second, we have the user-data file:
#cloud-config
autoinstall:
version: 1
locale: en_US
keyboard:
layout: us
ssh:
install-server: true
allow-pw: true
disable_root: true
ssh_quiet_keygen: true
allow_public_ssh_keys: true
packages:
- qemu-guest-agent
- sudo
storage:
layout:
name: direct
swap:
size: 0
user-data:
package_upgrade: false
timezone: America/Chicago
users:
- name: ubuntu
passwd: "$6$rounds=4096$repeatrepeat$repeatrepeatrepeatrepeatrepeatrepeatrepeatrepeatrepeatrepeat"
groups: [adm, sudo]
lock-passwd: false
sudo: ALL=(ALL) NOPASSWD:ALL
shell: /bin/bashRunning the Packer build
Once you have all the files in place, including your downloaded Packer exe, we need to run a couple of commands. First, we need to initialize Packer:
packer init .
Next, we run our packer build command:
packer build .
After the build completes, you should see the new Proxmox VM template in your inventory:
Wrapping up
Hopefully, this post will help anyone that would like to try out Ubuntu Server 26.04 LTS in Proxmox using an automated build process with Hashicorp Packer. The process is straightforward and only requires just a few files to be in place and the download for Packer and Ubuntu Server 26.04. Automating your build using Packer is a great way to start getting a feel for automating your home lab environment. How about you? Are you already using Packer along with Proxmox for automated builds?
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