You could set up each virtual machine by mounting the installation iso image to your virtual machine’s virtual disk drive and proceeding through the installer. In fact this is what I recommend for new users, but I will be using a software known as Packer to create Linux templates that I can use in VirtualBox or even other hypervisors.
To create a virtual machine, you need a CPU that supports virtualization and hypervisor software to emulate computer hardware within software. I recommend starting with VirtualBox since this is an open-source hypervisor that you can install on Windows, macOS, or Linux.
Packer makes it easier to perform unattended/automated installations of operating systems focused on virtual platforms but the community has also extended Packer to build Raspberry Pi images.
I would also recommend installing this software with Chocolatey. If you are not familiar with Chocolatey, I suggest checking out my previous post. Once you have Chocolatey installed you can install Rufus with one command:
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chocoinstallpacker
Packer on macOS
I would recommend installing Packer with homebrew on macOS. Once you have homebrew installed, you can install Packer with one command:
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brew install packer
Packer on Linux
I would recommend installing Packer with your distribution’s package manager if possible. Once you add the Hashicorp repo to your system you can also install other tools like Terraform. Otherwise, you can download the latest compiled binary from the website.
Building a Proxmox template with Packer
Proxmox is a Linux distribution where you can run virtual machines and containers and there is a nice web application for managing those resources. Check out my previous post for more information about Proxmox. You will need to use the default root credentials for Proxmox or create an API user with appropriate permissions.
Packer can have a bit of a steep learning curve if you are not familiar with JSON files. In fact, the makers of Packer now recommend you use their own template language HCL. If you are just getting started, I recommend using an existing set of Packer templates and provisioning scripts.
Proxmox API user
Enter the following commands to create an API user for Packer from the Proxmox host’s shell:
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pveum user add packerapi@pve -comment "Packer API user"# Create a password for the new userpveum passwd packerapi@pve
# Create a role with the appropriate permissionspveum role add Packer -privs "Datastore.AllocateSpace Sys.Modify VM.Config.Disk VM.Config.CPU VM.Config.Memory VM.Config.Options VM.Allocate VM.Audit VM.Console VM.Config.CDROM VM.Config.Network VM.PowerMgmt VM.Config.HWType VM.Monitor"# Assign the packer user the Packer rolepveum acl modify / -user packerapi@pve -role Packer
Example with a Debian template
Packer supports creating Proxmox templates from .iso images or existing virtual machines. This example will use a Debian .iso image to create a Proxmox VM template for creating additional virtual machines. Make a directory on your computer for the template files like this:
The http subdirectory is for presenting the unattended installation files to Proxmox. The scripts subdirectory contains a script to randomize the machine UUID so the template can be reused.
Here is the unattended installation config that works well for Debian. The settings here are for the United States Eastern time zone.
{"variables":{"username":"api@pve","password":"password","pmox_url":"https://proxmox.url:8006/api2/json","guest_hostname":"packer-deb10","ssh_user":"debian","ssh_pass":"debian","iso_location":"https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-10.9.0-amd64-xfce-CD-1.iso","checksum":"sha256:6e507be9fd35c8a7c6be00aefa5b550ed3d8641432b2ae533295f4bb5246642b"},"builders":[{"type":"proxmox","proxmox_url":"{{ user `pmox_url`}}","insecure_skip_tls_verify":true,"username":"{{ user `username`}}","password":"{{ user `password`}}","node":"pve","network_adapters":[{"bridge":"vmbr0","model":"virtio"}],"disks":[{"type":"scsi","disk_size":"64G","storage_pool":"local-lvm","storage_pool_type":"lvm-thin","format":"raw"}],"cores":2,"sockets":1,"memory":2048,"os":"l26","qemu_agent":true,"scsi_controller":"virtio-scsi-single","iso_url":"{{ user `iso_location` }}","iso_checksum":"{{ user `checksum` }}","iso_storage_pool":"local","http_directory":"http","boot_wait":"10s","boot_command":["<esc><wait>","install <wait>"," preseed/url=http://{{ .HTTPIP }}:{{ .HTTPPort }}/deb10/preseed.cfg <wait>","debian-installer=en_US.UTF-8 <wait>","auto <wait>","locale=en_US.UTF-8 <wait>","kbd-chooser/method=us <wait>","keyboard-configuration/xkb-keymap=us <wait>","netcfg/get_hostname={{ user `guest_hostname` }} <wait>","netcfg/get_domain=localdomain <wait>","fb=false <wait>","debconf/frontend=noninteractive <wait>","console-setup/ask_detect=false <wait>","console-keymaps-at/keymap=us <wait>","grub-installer/bootdev=/dev/sda <wait>","<enter><wait>"],"ssh_username":"{{ user `ssh_user` }}","ssh_timeout":"15m","ssh_password":"{{ user `ssh_pass`}}","unmount_iso":true,"template_name":"{{ user `guest_hostname` }}","template_description":"Debian 10 Template created by packer"}],"provisioners":[{"type":"shell","execute_command":"echo '{{ user `ssh_pass`}}' | {{.Vars}} sudo -S -E bash '{{.Path}}'","script":"scripts/deb10-seal.sh"}]}
Once these files are assembled, the template can be created with the packer build command. I recommend always running packer validate before running the build.
Example end of output for a successful build:
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==> proxmox: Converting VM to template
Build 'proxmox' finished after 8 minutes 8 seconds.
==> Wait completed after 8 minutes 8 seconds
==> Builds finished. The artifacts of successful builds are:
--> proxmox: A template was created
Building a VirtualBox template with Packer
Packer can also build a template for VirtualBox. Packer will boot a VM, install the OS, run any configuration scripts you add, shutdown the VM, and convert it to an OVF template. You can use that template to create new Virtual Machines that already have the Operating System installed.
Here is an example to create a Debian Linux template:
Once these files are assembled, the template can be created with the packer build command. I recommend always running packer validate before running the build.
Example end of output for a successful build:
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Build 'virtualbox-iso' finished after 5 minutes 11 seconds.
==> Wait completed after 5 minutes 11 seconds
==> Builds finished. The artifacts of successful builds are:
--> virtualbox-iso: VM files in directory: output-virtualbox-iso
Packer will create an OVF file and a virtual machine hard disk in the specified directory. This template can be used to create new virtual machines.
