How to build a Packer image for Azure

Build a Packer image for Azure

To demonstrate how Packer works, we'll use it to build a Windows Server image. To start, download and install Packer for the operating system of choice. Packer offers an installation guide on its website.

Next, we need to figure out where to create the image. A Packer feature called builders creates images for various services, such as Azure, AWS, Docker, VMware and more. This tutorial will explain how to build a Windows Server image to run in Azure.

To construct an image for Azure, we have to meet a few prerequisites. You need:

• a service principal for Packer to authenticate to Azure;
• a storage account to hold the image;
• the resource group name for the storage account;
• the Azure subscription ID;
• the tenant ID for your Azure Active Directory; and
• a storage container to place the VHD image.

Validate the Windows Server build instructions

A Packer feature called builders creates images for various services, such as Azure, AWS, Docker, VMware and more.

Next, it's time to set up the image template. Every Packer image requires a JSON file called a template that tells Packer how to build the image and where to put it. An example of a template that builds an Azure image is in the code below. Save it with the filename WindowsServer.Azure.json.

{
  "variables": {
      "client_id": "",
      "client_secret": "",
      "object_id": ""
  },
  "builders": [{
    "type": "azure-arm",

    "client_id": "{{user `client_id`}}",
    "object_id": "{{user `object_id`}}",
    "client_secret": "{{user `client_secret`}}",
    "resource_group_name": "labtesting",
    "storage_account": "adblabtesting",
    "subscription_id": "d660a51f-031d-4b8f-827d-3f811feda5fc",
    "tenant_id": "bb504844-07db-4019-b1c4-7243dfc97121",

    "capture_container_name": "vhds",
    "capture_name_prefix": "packer",

    "os_type": "Windows",
    "image_publisher": "MicrosoftWindowsServer",
    "image_offer": "WindowsServer",
    "image_sku": "2016-Datacenter",
    "location": "East US",
    "vm_size": "Standard_D2S_v3"
  }]
}

You should validate the schema before you start with the packer validate command. We don't want sensitive information in the template, so we create the client_id and client_secret variables and pass those at runtime.

packer validate -var 'client_id=value' -var 'client_secret=value' WindowsServer.Azure.json

How to correct Packer build issues

After the command confirms the template is good, we build the image with nearly the same syntax as the validation command. For the purposes of this article, we will use placeholders for the client_id, client_secret and object_id references.

> packer build -var 'client_id=XXXX' -var 'client_secret=XXXX' -var 'object_id=XXXX' WindowsServer.Azure.json

When you run the build the first time, you may run into a few errors if the setup is not complete. Here are the errors that came up when I ran my build:

• "Build 'azure-arm' errored: The storage account is located in eastus, but the build will take place in West US. The locations must be identical"
• Build 'azure-arm' errored: storage.AccountsClient#ListKeys: Failure responding to request: StatusCode=404 – Original Error: autorest/azure: Service returned an error. Status=404 Code="ResourceGroupNotFound" Message="Resource group 'adblabtesting' could not be found."

• "==> azure-arm: ERROR: -> VMSizeDoesntSupportPremiumStorage : Requested operation cannot be performed because storage account type 'Premium_LRS' is not supported for VM size 'Standard_A2'."

The error messages are straightforward and not difficult to fix.

However, the following error message is more serious:

==> azure-arm: ERROR: -> Forbidden : Access denied
==> azure-arm:
==> azure-arm:  ...failed to get certificate URL, retry(0)

This indicates the use of the wrong object_id. Find the correct one in the Azure subscription role.

After adding the right object_id, you will find a VHD image in Azure.