Understand guest configuration assignment resources

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When an Azure Policy is assigned, if it's in the category "Guest Configuration" there's metadata included to describe a guest assignment.

You can think of a guest assignment as a link between a machine and an Azure Policy scenario. For example, the following snippet associates the Azure Windows Baseline configuration with minimum version 1.0.0 to any machines in scope of the policy.

"metadata": {
    "category": "Guest Configuration",
    "guestConfiguration": {
        "name": "AzureWindowsBaseline",
        "version": "1.*"
    }
//additional metadata properties exist

How Azure Policy uses guest configuration assignments

The metadata information is used by the guest configuration service to automatically create an audit resource for definitions with either AuditIfNotExists or DeployIfNotExists policy effects. The resource type is Microsoft.GuestConfiguration/guestConfigurationAssignments. Azure Policy uses the complianceStatus property of the guest assignment resource to report compliance status. For more information, see getting compliance data.

Deletion of guest assignments from Azure Policy

When an Azure Policy assignment is deleted, if a guest configuration assignment was created by the policy, the guest configuration assignment is also deleted.

When an Azure Policy assignment is deleted from an initiative, if a guest configuration assignment was created by the policy, you will need to manually delete the corresponding guest configuration assignment. This can be done by navigating to the guest assignments page on Azure portal and deleting the assignment there.

Manually creating guest configuration assignments

Guest assignment resources in Azure Resource Manager can be created by Azure Policy or any client SDK.

An example deployment template:

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "resources": [
    {
      "apiVersion": "2021-01-25",
      "type": "Microsoft.Compute/virtualMachines/providers/guestConfigurationAssignments",
      "name": "myMachine/Microsoft.GuestConfiguration/myConfig",
      "location": "chinanorth2",
      "properties": {
        "guestConfiguration": {
          "name": "myConfig",
          "contentUri": "https://mystorageaccount.blob.core.chinacloudapi.cn/mystoragecontainer/myConfig.zip?sv=SASTOKEN",
          "contentHash": "SHA256HASH",
          "version": "1.0.0",
          "assignmentType": "ApplyAndMonitor",
          "configurationParameter": {}
        }
      }
    }    
  ]
}

The following table describes each property of guest assignment resources.

Property Description
name Name of the configuration inside the content package MOF file.
contentUri HTTPS URI path to the content package (.zip).
contentHash A SHA256 hash value of the content package, used to verify it has not changed.
version Version of the content package. Only used for built-in packages and not used for custom content packages.
assignmentType Behavior of the assignment. Allowed values: Audit, ApplyandMonitor, and ApplyandAutoCorrect.
configurationParameter List of DSC resource type, name, and value in the content package MOF file to be overridden after it's downloaded in the machine.

Deletion of manually created guest configuration assignments

Guest configuration assignments created through any manual approach (such as an Azure Resource Manager template deployment) must be deleted manually. Deleting the parent resource (virtual machine or Arc-enabled machine) will also delete the guest configuration assignment.

To manually delete a guest configuration assignment, use the following example. Make sure to replace all example strings, indicated by "<>" brackets.

# First get details about the guest configuration assignment
$resourceDetails = @{
  ResourceGroupName = '<myResourceGroupName>'
  ResourceType      = 'Microsoft.Compute/virtualMachines/providers/guestConfigurationAssignments/'
  ResourceName      = '<myVMName>/Microsoft.GuestConfiguration'
  ApiVersion        = '2020-06-25'
}
$guestAssignment = Get-AzResource @resourceDetails

# Review details of the guest configuration assignment
$guestAssignment

# After reviewing properties of $guestAssignment to confirm
$guestAssignment | Remove-AzResource

Next steps