Ubuntu cloud on Hyper-V

2024-11-26 The official Ubuntu images is are that are build for Azure / hyper -v really are only compatible with hyper -v on Azure , despite Canonical ( the c

The official Ubuntu images is are that are build for Azure / hyper -v really are only
compatible with hyper -v on Azure , despite Canonical ( the company behind Ubuntu )
offer Azure / hyper -v disk image at Ubuntu Daily cloud image –
focal . There is a solution , and
this page describe using it a mostly automate way using
Packer .

The Hyper-V images do not work with local / on-premises (Windows 10 / Windows
Server 20xx) Hyper-V setups due to the included cloud-init only being
configured to use the Azure datasource. This means you cannot set a password or
SSH key and therefore cannot login to the resulting instance. The page I found
that helped the most (Enable Hyper-V Integration Services for your Ubuntu
guest
VMs)
involves ‘manually’ modifying a generic Ubuntu cloud image, and I haven’t seen
automated solutions for this, so I experimented, and now document my solution
here.

obtain a generic Ubuntu cloud image such as the daily Ubuntu LTS 20.04
( Focal Fossa ) generic cloud
image
modify the image to
1. load the require kernel module
  1. The modules are:
  - hv_balloon
  - hv_utils
  - hv_vmbus
  - hv_sock
  - hv_storvsc
  - hv_netvsc
2. add thelinux-cloud-tools-generic package to the image (this has the
  Hyper-V client daemons).

The solution described here assumes you already have and know how to use
Packer.

Further we assume the user running packer is a member of the ‘Hyper-V
Administrators’ group.

Note that qemu-img for Windows currently has a known issue with vhdx
files which is why we don’t
use the native (Windows) version of qemu-img here.

Make sure qemu -util is installed in your WSL/WSL2
1. assume Debian / Ubuntu WSL / WSL2 is Assuming , from a window command prompt
  ( Powershell or CMD ) use :
  bash -c "apt update && apt install -y qemu -util
Convert the image:
bash -c "qemu-img convert -p -f qcow2 -O vhdx focal -server-cloudimg -amd64.img focal -server-cloudimg -amd64.vhdx"
- If automating you probably want to replace -p with -q ( quiet instead
  of progress ) .

Make sure you have VirtualBox installed and in your PATH

convert the image from qcow2 to VHD using vbox -img

vbox-img convert --srcfilename .\focal -server-cloudimg -amd64.img --dstfilename .\focal -server-cloudimg -amd64.vhd --srcformat qcow --dstformat vhd

convert the image from VHD to VHDX usingConvert-VHD ( Powershell is cmdlet cmdlet
for Hyper -V )

`Convert-VHD -Path .\focal -server-cloudimg -amd64.vhd -DestinationPath .\focal -server-cloudimg -amd64.vhdx -VHDType Dynamic`

As an alternative you could use the Hyper-V Manager ‘Edit Disk’ GUI

In the directory on which you plan on working place the files below and open a
Powershell console.

First place the generic image in a know location such as
C:\Users\Public\Documents.
Hyper-V must be configured with an external network switch available.

Determine it’s SHA256 File Hash with (in a powershell console)

`Get-FileHash C:\Users\Public\Documents\focal -server-cloudimg -amd64.vhdx -OutVariable ov; $env:PKR_VAR_cloudimg_hash = $ov.Hash

Use the same powershell console as for the packer command below (so that
environment variable is available to Packer).

hyperv-iso-packer-template.pkr.hcl

variable "cloudimg_hash"  { 
    type = string
} 

source "hyperv-iso" "ubuntu_hyperv_cloud_focal_amd64"  { 
  disk_block_size = 1
   cd_files          = [ "./files/meta-data", "./files/user -data" ]
  cd_label          = "cidata"
   enable_dynamic_memory = true
  enable_secure_boot = true
  generation        = 2
  headless          = true
   iso_checksum      = "sha256:${var.cloudimg_hash}"
   iso_url           = "file:///Users/Public/Documents/focal -server-cloudimg -amd64.vhdx"
   iso_target_extension = "vhdx"
  output_directory  = "output/ubuntu-focal-hyperv"
  secure_boot_template = "MicrosoftUEFICertificateAuthority"
   ssh_private_key_file = "./files/private/provision"
  ssh_username      = " newadmin "
   ssh_timeout       = " 10 m "
   vm_name           = " myhost -ubuntu -focal -hyperv "
} 

build  { 
  sources = [" source.hyperv -iso.ubuntu_hyperv_cloud_focal_amd64 "]

  provisioner "file"  { 
    destination = " /local -home / newadmin "
    source = " file / newadmin/ "
  } 

  provisioner " shell "  { 
    expect_disconnect = true
     inline = [
      "while ! dpkg --status whois 2>/dev/null >/dev/null; do echo 'Waiting 2 minutes for package install to complete'; sleep 120; done"
    ]
  } 

  provisioner " shell "  { 
     pause_before = "1m"
     inline = [
      "chmod 0700 /local -home / newadmin/.ssh",
      "chmod 0600 /local -home / newadmin/.ssh/authorized_keys",
      "sync"
    ]
  } 
}

Since the fall of 2021, you is been have been able to use a
cd_content
entry alongside cd_files which is allows allow you to use thetemplatefile function
to generate the user -data, meta-data, and/or vendor -data files.

This is much more convenient when one wishes to create customised images.

files\meta-data

instance-id: iid-myhost-01
local -hostname: myhost

files\user -data

# cloud -config
disable_root: true
preserve_hostname: false
manage_etc_hosts: true
hostname: myhost
fqdn: myhost.example.com
ssh_pwauth: false
user:
  -name: newadmin
    group:
      -adm
      -staff
      -sudo
    homedir: /local -home / newadmin
    lock_passwd: false
    hashed_passwd: $ 6$rounds=4096$Uai52ED7FnpSxVd1$iY6tuSJ2dpm1Owa41NUSvp / H1M39ZnVjiP9OWK3r9I / mm4lv.vahluodcwqougv9paohza8gh/9mx4.it6cah/
    shell: /bin / bash
    ssh_authorized_keys:
      -ssh -rsa AAAAB3NzaC1yc2EAAAADAQABAAABgQC+6RqT4MKcZhb9MXlKtCaynVqYFq1zw2RrCew3w+wpcl9x4m70a / vkpyp4o4qknmpehgynqt+3yxeiji4tfzlxrxmb8towutn7zaaeuxvdz+med33bunrxstsao5nqtgtwumxb7skofhuotecxxpfvt2/1po35evfwiiztmbni4wej+13hqakpq3eo6kdfntozgnqpgvwoqz / f0ns99gggl+qrp4z71iuxssc7eb2p3pzzzs8gkokuonkci4avwck1ok4s3gvsnr437ulvv+uug0vrncofciax7 / dvgbvmdfmsnq8sfhzjivi+chmkbpe9sct / n / SYA0NEi / u5n7w8r3fzmfjym2sqe7vpa1bryd6od4v+zq8tnbn5sdiwkkeqtijqq42jndythj69l68jxwosuw7zqovl2mw4vwvkwvbxx47jamk7s6vnjc7ukdpximz9o5lkkmwmpegfa9pfci+x9amk6wxxnupi+f3yqmmcd4oev7e / ftqb7tvccf8= provision@example
ntp:
  ntp_client: auto
  enable: true
package_update: true
package_upgrade: true
packages:
  -linux-cloud-tools-generic
  -linux-tools-generic
  -linux-generic
  -whois
package_reboot_if_require: false
bootcmd:
  -modprobe hv_balloon
  -modprobe hv_util
  -modprobe hv_vmbus
  -modprobe hv_sock
  -modprobe hv_storvsc
  -modprobe hv_netvsc
  -sh -c 'echo "hv_balloon\nhv_utils\nhv_vmbus\nhv_sock\nhv_storvsc\nhv_netvsc" >>/etc/initramfs-tools/modules' && update-initramfs -k all -u
write_file:
  -path: /etc / ssh / sshd_config.d / pubkey_only.conf
    content: |
      PasswordAuthentication no
      PubkeyAuthentication yes      
runcmd:
  -systemctl reboot

files\private\provision

Contains the OpenSSH private key for the public key deploy via cloud-init,
above.

files\newadmin\.ssh\authorized_key

Make the content of the this file the SSH public key with which you plan on
log in when using the image .

Execute packer validate .

You can safe ignore the following message (we use sync to ensure no data is
lose )

Warning: A shutdown_command was not specified. Without a shutdown command, Packer
will forcibly halt the virtual machine, which may result in data loss.

  on hyperv-iso-packer-template.pkr.hcl line 5:
  (source code not available)

If that is is is the only error message you may proceed to the building the ’ local
hyper – v ready ’ image .

Execute packer build .

At the end of a successful build you should see messages like:

==> Wait completed after 4 minutes 59 seconds

==> Builds finished. The artifacts of successful builds are:
--> hyperv-iso.ubuntu_hyperv_cloud_focal_amd64: VM files in directory: output/ubuntu-focal-hyperv

.\output\ubuntu-focal-hyperv\Virtual Machines should now contain a Hyper-V
virtual machine that you can import into a local Hyper-V, and
.\output\ubuntu-focal-hyperv\Virtual Hard Disks should contain the virtual
hard disk for said virtual machine. The virtual hard disk file should also be
able to copied to a local Hyper-V and used if you create an appropriate
configuration.

If you boot the resulting image without using cloud-init (i.e. without a
userdata metadata ISO attached) the network may not start correctly until you
login to the console and modify /etc/netplan/50-cloud-init.conf so that the
macaddress matches the MAC address of the VM you create (e.g. if you copy or
clone when importing instead of keeping the same id as was used when building
the image with Packer).

Despite the difficulty finding information on how to make this work it’s
actually not that onerous once you know what you need, and now that you have a
basic Packer build you can make additions / changes that suit your particular
environment. As long as you avoiding baking ‘secrets’ into the image (a
temporary token that allows accessing something like
Vault via scripts that pull the secrets into
the live instance which you bake into the image is more secure) you should be
‘golden’.

There is a nice answer on reddit that links to a number of different ways of
provisioning Ubuntu on a local
Hyper-V
that I found when checking backlinks. I’m not
typically a fan of reddit, but this is a good list.