template.json

{
  "variables": {
    "sn": "Free Trial",
    "ps": "d:/Packer.io/example/ps.publishsettings",
    "sa": "packerdemo",
    "scripts": "d:/Packer.io/example/Azure",
    "image_label": "Windows Server 2012 R2 Datacenter, January 2016"
  },
  "builders": [
    {
      "type": "azure",
      "publish_settings_path": "{{user `ps`}}",
      "subscription_name": "{{user `sn`}}",
      "storage_account": "{{user `sa`}}",
      "storage_account_container": "images",
      "os_type": "Windows",
      "os_image_label": "{{user `image_label`}}",
      "location": "North Europe",
      "instance_size": "Medium",
      "user_image_label": "PackerMadeWindowsSlave"
    }
  ],
  "provisioners": [
    {
      "type": "azure-custom-script-extension",
      "distr_src_path": "{{user `scripts`}}/jenkins_config",
      "script_path": "{{user `scripts`}}/setup.ps1"
    }
  ]
}