coreos container linux OVA generation using Packer

packer-build.json

{
  "variables": {
    "name": "coreos-baseimage",
    "release": "stable",
    "iso_checksum": "",
    "iso_checksum_type": "none",
    "disk_size": "40000",
    "cpus": "4",
    "memory": "2048",
    "boot_wait": "15s",
    "ignition": "ignition.json",
    "vsphere_host": "some host",
    "vsphere_username": "[email protected]",
    "vsphere_password": "some password",
    "vsphere_datacenter": "some DC",
    "vsphere_resource_pool": "some pool",
    "vsphere_folder": "some folder",
    "vsphere_datastore": "some store"
  },
  "builders": [{
    "name": "{{user `name`}}",
    "guest_os_type": "Linux_64",
    "headless": true,
    "type": "virtualbox-iso",
    "iso_url": "coreos_production_iso_image.iso",
    "iso_checksum": "d97ed6c250f2037b6fd92471c2890176",
    "iso_checksum_type": "md5",
    "ssh_username": "core",
    "ssh_password": "packer",
    "shutdown_command": "sudo shutdown -h now",
    "format": "ovf",
    "boot_wait": "{{user `boot_wait`}}",
    "boot_command": [
      "sudo passwd core<enter><wait>",
      "packer<enter>",
      "packer<enter>",
      "sudo systemctl start sshd.service<enter>"
    ],
    "vboxmanage": [
      ["modifyvm", "{{.Name}}", "--memory",  "{{user `memory`}}"],
      ["modifyvm", "{{.Name}}", "--cpus",  "{{user `cpus`}}"],
      ["modifyvm", "{{.Name}}", "--audio",  "none"]
    ]
  }],
  "provisioners": [
    {
      "type": "file",
      "source": "{{ user `ignition` }}",
      "destination": "/tmp/ignition.json"
    },
    {
        "type": "shell",
        "inline": [
            "sudo coreos-install -d /dev/sda -C {{ user `release` }} -o vmware_raw"
        ]
    }
  ],
  "post-processors": [{
    "type":            "vsphere-template",
    "host":            "{{user `vsphere_host`}}",
    "username":        "{{user `vsphere_username`}}",
    "password":        "{{user `vsphere_password`}}",
    "datacenter":      "{{user `vsphere_datacenter`}}",
    "resource_pool":   "{{user `vsphere_resource_pool`}}",
    "folder":          "{{user `vsphere_folder`}}",
    "datastore":       "{{user `vsphere_datastore`}}",
    "v_app_properties": [
      {
        "label": "Hostname",
        "description": "Hostname",
        "metadata": {
          "user_configurable": true,
          "type": "string",
          "key": "guestinfo.hostname",
          "value": ""
        }
      },
      {
        "label": "CoreOS config data",
        "description": "Inline cloud-config data",
        "metadata": {
          "user_configurable": true,
          "type": "string",
          "key": "guestinfo.coreos.config.data",
          "value": ""
        }
      },
      {
        "label": "CoreOS config url",
        "description": "URL to cloud-config data",
        "metadata": {
          "user_configurable": true,
          "type": "string",
          "key": "guestinfo.coreos.config.url",
          "value": ""
        }
      },
      {
        "label": "CoreOS config data encoding",
        "description": "Encoding for cloud-config data",
        "metadata": {
          "user_configurable": true,
          "type": "string",
          "key": "guestinfo.coreos.config.data.encoding",
          "value": ""
        }
      },
      {
        "label": "Name for network interface 0",
        "description": "Name for network interface 0",
        "metadata": {
          "user_configurable": true,
          "type": "string",
          "key": "guestinfo.interface.0.name",
          "value": ""
        }
      },
      {
        "label": "MAC for network interface 0",
        "description": "MAC for network interface 0",
        "metadata": {
          "user_configurable": true,
          "type": "string",
          "key": "guestinfo.interface.0.mac",
          "value": ""
        }
      },
      {
        "label": "DHCP support for network interface 0",
        "description": "DHCP support for network interface 0",
        "metadata": {
          "user_configurable": true,
          "type": "string",
          "key": "guestinfo.interface.0.dhcp",
          "value": ""
        }
      },
      {
        "label": "Role for network interface 0",
        "description": "Role for network interface 0",
        "metadata": {
          "user_configurable": true,
          "type": "string",
          "key": "guestinfo.interface.0.role",
          "value": ""
        }
      },
      {
        "label": "Main IP for network interface 0",
        "description": "Main IP for network interface 0",
        "metadata": {
          "user_configurable": true,
          "type": "string",
          "key": "guestinfo.interface.0.ip.0.address",
          "value": ""
        }
      },
      {
        "label": "Main route gateway for network interface 0",
        "description": "Main route gateway for network interface 0",
        "metadata": {
          "user_configurable": true,
          "type": "string",
          "key": "guestinfo.interface.0.route.0.gateway",
          "value": ""
        }
      },
      {
        "label": "Main route destination for network interface 0",
        "description": "Main route destination for network interface 0",
        "metadata": {
          "user_configurable": true,
          "type": "string",
          "key": "guestinfo.interface.0.route.0.destination",
          "value": ""
        }
      },
      {
        "label": "Primary DNS",
        "description": "Primary DNS",
        "metadata": {
          "user_configurable": true,
          "type": "string",
          "key": "guestinfo.dns.server.0",
          "value": ""
        }
      },
      {
        "label": "Secondary DNS",
        "description": "Secondary DNS",
        "metadata": {
          "user_configurable": true,
          "type": "string",
          "key": "guestinfo.dns.server.1",
          "value": ""
        }
      }
    ]
  }]
}

More context on Github issue here.