Help - CoreOS/Hyperv-iso not working

Hello everyone,

I’m new in Packer world and I’m stuck in a few days trying to create an hyperv image using CoreOS as ‘iso’.
Here’s the template that I’m using right now:

"description": "CoreOS image for a VirtualBox platform.",

"builders": [{
  "type": "hyperv-iso",
  "iso_url": "",
  "iso_checksum": "5d41fe61404f298a87f303d766b84d3b",
  "iso_checksum_type": "md5",
  "ssh_username": "packer",
  "ssh_password": "packer",
  "vm_name": "testvm",
  "memory": 3000,
   "ssh_timeout" : "10m",
  "shutdown_command": "echo 'packer' | sudo -S shutdown -P now",
  "boot_wait": "50s",
  "http_directory": "./extra/files",
  "boot_command": [
    "sudo -i<enter>",
    "systemctl stop sshd.socket<enter>",
    "wget http://{{ .HTTPIP }}:{{ .HTTPPort }}/install.yml<enter>",
    "coreos-install -d /dev/sda -C {{user `channel`}} -c install.yml<enter>",


Error: [DEBUG] Error getting SSH address: No ip address
Timeout waiting for SSH.