Introduction
In today’s fast-paced IT landscape, automation isn’t just a luxury—it’s a necessity. If you’re managing Windows virtual machines in a VMware environment, this blog is for you. We’re about to explore a game-changing solution: Packer by HashiCorp. Strap in as we take a deep dive into how automated Windows image building with Packer can transform your VMware deployments!
The Pain of Manual Image Building
Think back to the last time you manually created a Windows image for VMware. Endless clicks, long wait times, and the ever-present potential for human error—it’s a tedious and often frustrating process. Worse yet, it’s time-consuming, error-prone, and often requires repeating the same steps across multiple environments.
What if there were a better way? Spoiler alert: there is, and it’s called Packer.
Meet Packer: Your New Best Friend
Packer, an open-source tool from HashiCorp, automates the creation of machine images across multiple platforms. When it comes to building Windows images for VMware, Packer is like having a reliable assistant that produces consistent, error-free images with minimal effort.
Here’s why Packer is about to become an essential tool in your VMware workflow.
Why Use Packer for Windows and VMware?
Consistency at Scale
Say goodbye to “it worked on my machine” problems. Packer ensures that your images are built consistently across all environments—development, testing, and production. This reliability reduces unexpected deployment issues, making troubleshooting much easier.Speed and Efficiency
Once you automate your image creation with Packer, you drastically cut down the time between image requests and deployments. Build once, deploy many times across different environments. The automation eliminates bottlenecks, allowing your team to move faster and focus on higher-value tasks.Version Control for Virtual Machines
Just like code, virtual machine images evolve over time. Packer integrates seamlessly with version control systems, allowing you to track changes, roll back to previous versions, and maintain a history of your images. This brings a whole new level of transparency and control to your VMware infrastructure.Multi-Cloud Flexibility
While today we’re focusing on VMware, it’s worth noting that Packer supports multiple platforms. Whether you’re deploying on AWS, Azure, or GCP, the same tool can be used to create images across all your environments, simplifying the management of multi-cloud deployments.
Let’s Get Started!
Download and install Packer by HashiCorp. You need an autounattend.xml file to modify the Windows settings in your images for the OS installation. You can generate your own autounattend.xml file using Windows System Image Manager. Point the utility to the install.wim, and you’re set to create the autounattend.xml file.
File Overview
Here’s a breakdown of the important files in the repository:
variables.pkr.hcl: Declares variables and optionally sets default values.windows.pkr.hcl: Contains the main Packer build configuration.data/autounattend.pkrtpl.hcl: Serves as an answer file to modify Windows settings during the image setup.scripts/windows/: Contains custom PowerShell scripts.
Here’s a sample windows.pkr.hcl file, which defines the configuration for building a Windows image using Packer and vSphere:
source "vsphere-iso" "autogenerated_1" {
CPUs = var.cpu_num
RAM = var.mem_size
RAM_reserve_all = true
cluster = var.vsphere_compute_cluster
communicator = "winrm"
convert_to_template = true
datacenter = var.vsphere_dc_name
datastore = var.vsphere_datastore
disk_controller_type = var.vm_disk_controller_type
firmware = "efi-secure"
floppy_files = ["setup/win22/efi/autounattend.xml", "setup/setup.ps1", "setup/vmtools.cmd"]
folder = var.vsphere_folder
guest_os_type = "windows2019srvNext_64Guest"
host = var.vsphere_host
insecure_connection = true
iso_paths = [var.os_iso_path, var.vmtools_iso_path]
boot_wait = "3s"
boot_command = [
"<spacebar><spacebar>"
]
network_adapters {
network = var.vsphere_portgroup_name
network_card = "vmxnet3"
}
password = var.vsphere_password
storage {
disk_size = var.disk_size
disk_thin_provisioned = true
}
username = var.vsphere_user
vcenter_server = var.vsphere_server
vm_name = var.vsphere_template_name
winrm_password = var.winadmin_password
winrm_username = "Administrator"
}
# Build block
build {
sources = ["source.vsphere-iso.autogenerated_1"]
provisioner "windows-shell" {
inline = ["dir c:\\"]
}
}
Here’s an example variables.pkr.hcl file, where the variables referenced in the windows.pkr.hcl file are declared:
variable "cpu_num" {
type = string
default = ""
}
variable "disk_size" {
type = string
default = ""
}
variable "mem_size" {
type = string
default = ""
}
variable "os_iso_path" {
type = string
default = ""
}
variable "vmtools_iso_path" {
type = string
default = ""
}
variable "vsphere_compute_cluster" {
type = string
default = ""
}
variable "vsphere_datastore" {
type = string
default = ""
}
variable "vsphere_dc_name" {
type = string
default = ""
}
variable "vsphere_folder" {
type = string
default = ""
}
variable "vsphere_host" {
type = string
default = ""
}
variable "vsphere_password" {
type = string
sensitive = true
}
variable "vsphere_portgroup_name" {
type = string
default = ""
}
variable "vsphere_server" {
type = string
default = ""
}
variable "vsphere_template_name" {
type = string
default = ""
}
variable "vsphere_user" {
type = string
default = ""
}
variable "winadmin_password" {
type = string
default = ""
sensitive = true
}
variable "vm_disk_controller_type" {
type = list(string)
description = "The virtual disk controller types in sequence. (e.g. 'pvscsi')"
default = ["pvscsi"]
}
Required version and plugins
Ensure you specify the required version of Packer and the necessary plugins, like the vsphere.iso plugin for VMware and the optional Windows Update plugin.
packer {
required_version = ">= 1.8.3"
required_plugins {
vsphere = {
version = ">= v1.0.8"
source = "github.com/hashicorp/vsphere"
}
}
required_plugins {
windows-update = {
version = ">= 0.14.1"
source = "github.com/rgl/windows-update"
}
}
}
Running Packer Commands
Navigate to the directory where all your files are located and run the following commands:
packer init . # Downloads required plugins for running the build(s).
packer validate . # Validates the syntax and configuration.
packer build . # Runs the build(s).
Best Practices for Automating Windows Image Builds
Script Everything
The more you can automate, the better. Use PowerShell scripts to automate OS configuration, software installation, and security updates.Use Source Control
Store your Packer templates in a version control system (like Git). This ensures that you have a clear history of changes to your images and can easily roll back to a previous version if something goes wrong.Test Before Deploying
It’s always a good idea to test your images before deploying them to production. Use a sandbox environment or a staging server to ensure everything works as expected.Regularly Update Your Base Images Security vulnerabilities and performance updates happen regularly. Be sure to update your base Windows images frequently to ensure your VMs are always up to date with the latest patches and security fixes.
Pro Tips
Answer Files for Automation: Use autounattend.xml files to automate Windows installation tasks and reduce manual intervention.
Leverage PowerShell: Include custom PowerShell scripts to handle post-install configurations. Whether it’s installing software or tuning system settings, PowerShell is your go-to tool.
Keep Secrets Secret: Use environment variables or HashiCorp Vault to manage sensitive data like passwords.
Test, Test, Test: Use Packer’s
--debugflag to pause at each step. It’s like having X-ray vision into your build process.
The Road Ahead
Automating Windows image builds with Packer for VMware is just the beginning. As you get more comfortable, you’ll find yourself automating more, sleeping better, and impressing your colleagues with your infrastructure wizardry.
Remember, the goal isn’t just to automate image building – it’s to free up your time for more interesting challenges. So go forth, Packer in hand, and conquer those Windows deployments!
Happy building, and may your VMs always be perfectly provisioned!