How Packer Functions

Packer utilizes a configuration or template file to dictate how the images are constructed. This configuration can be in either JSON or HashiCorp Configuration Language (HCL2).

The image creation process with Packer follows these steps:

1. Packer initiates an instance using a base image or ISO, whether locally, on a remote server, or in the cloud.
2. It runs configuration tools, such as Ansible or custom scripts, to set up the instance to the desired specifications.
3. Finally, it generates the image and retrieves it from ESXi or the host on which the image was created.

For KVM, Packer employs QEMU to build the image, while for VMWare—our primary focus here—it leverages a VMWare ESXi server.

In this guide, I will demonstrate how to use Packer to create a Rocky Linux 8.6 operating system image compatible with both KVM and VMWare, serving as a golden image suitable for various environments and applications. With minor adjustments, this procedure can easily be adapted for additional platforms.

Installing Packer

You can find installation instructions and packages at the designated URL.

Sample Packer Template/Configuration File

This configuration file is a fully operational template for building Rocky Linux 8.6 compatible with both KVM/QEMU and VMWare.

variable "root_user" {

type = string

default = "root"

sensitive = true

}

variable "root_pw" {

type = string

default = "myExamplePw289@@"

sensitive = true

}

variable "vmware_user" {

type = string

}

variable "vmware_host" {

type = string

}

variable "vmware_pw" {

type = string

sensitive = true

}

variable "out_dir" {

type = string

default = "images"

}

variable "version" {

type = string

}

locals {

version = "rocky-8.6–1.0"

iso_name = "Rocky-8.6-x86_64-dvd1.iso"

iso_checksum = "sha256:1d48e0af63d07ff4e582a1819348e714c694e7fd33207f48879c2bc806960786"

}

source "qemu" "lvm-resize" {

iso_url = local.iso_name

iso_checksum = local.iso_checksum

output_directory = var.out_dir

shutdown_command = "shutdown -P now"

disk_compression = true

disk_size = "7500M"

memory = 1024

format = "qcow2"

accelerator = "kvm"

http_directory = "kickstarts"

ssh_username = var.root_user

ssh_password = var.root_pw

ssh_timeout = "30m"

vnc_bind_address = "0.0.0.0"

vnc_port_min = "5900"

vnc_port_max = "5909"

vm_name = "{{ build_name }}-${var.version}.qcow2"

net_device = "virtio-net"

disk_interface = "virtio"

boot_wait = "5s"

headless = true

boot_command = [" text inst.ks=http://{{ .HTTPIP }}:{{ .HTTPPort }}/lvm-resize.ks"]

qemu_img_args {

convert = ["-o", "compat=0.10"] # compatibility with older centos6 hypervisors

}

}

source "vmware-iso" "lvm-resize-vmware" {

format = "ovf"

guest_os_type = "centos-64"

iso_url = local.iso_name

iso_checksum = local.iso_checksum

output_directory = var.out_dir

vm_name = "{{ build_name }}-${var.version}"

vmdk_name = "{{ build_name }}-${var.version}-disk"

disk_type_id = "thin"

keep_registered = false

disk_size = 102400

memory = 4096

cpus = 4

http_directory = "kickstarts"

http_port_min = 8000

http_port_max = 8009

headless = false

boot_wait = "5s"

remote_host = var.vmware_host

remote_username = var.vmware_user

remote_password = var.vmware_pw

remote_type = "esx5"

skip_compaction = false

shutdown_command = "shutdown -P now"

ssh_port = "22"

ssh_timeout = "30m"

ssh_username = var.root_user

ssh_password = var.root_pw

vnc_bind_address = "0.0.0.0"

vnc_port_min = 5900

vnc_port_max = 5909

vnc_disable_password = true

boot_command = [

" text net.ifnames=0 biosdevname=0 ip=10.89.91.241::10.89.90.1:255.255.254.0:vmware:eth0:none ks=http://{{ .HTTPIP }}:{{ .HTTPPort }}/lvm-resize-vmware.ks"

]

vmx_data = {

"ethernet0.addressType" = "generated"

"ethernet0.networkName" = "VM Network"

"ethernet0.present" = "TRUE"

"ethernet0.startConnected" = "TRUE"

}

}

In the above example, the ISO can be stored locally or specified as a remote URL for Packer to download. For expediency during testing, I opted for a local ISO.

If you wish to monitor the installation progress for QEMU/KVM builds, you can connect to the VM being built using VNC. Packer will provide the port number for this connection.

For VMWare ESXi settings, I keep the credentials in a separate file for security purposes.

{

"vmware_host": "10.89.91.99",

"vmware_user": "root",

"vmware_pw": "MyAm@z1ngP@ssw0rd"

}

This is the kickstart file utilized for image creation, structured for templating.

Building the Images

To initiate the image creation, execute the command.

This video demonstrates how to utilize HashiCorp Packer for building a custom Ubuntu 22.04 image in VMware vSphere.