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Use Azure Disk Encryption with Virtual Machine Scale Set extension sequencing

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Extensions such as Azure disk encryption can be added to an Azure virtual machines scale set in a specified order. To do so, use extension sequencing.

In general, encryption should be applied to a disk:

  • After extensions or custom scripts that prepare the disks or volumes.
  • Before extensions or custom scripts that access or consume the data on the encrypted disks or volumes.

In either case, the provisionAfterExtensions property designates which extension should be added later in the sequence.

Sample Azure templates

If you wish to have Azure Disk Encryption applied after another extension, put the provisionAfterExtensions property in the AzureDiskEncryption extension block.

Here is an example using "CustomScriptExtension", a PowerShell script that initializes and formats a Windows disk, followed by "AzureDiskEncryption":

"virtualMachineProfile": {
  "extensionProfile": {
    "extensions": [
      {
        "type": "Microsoft.Compute/virtualMachineScaleSets/extensions",
        "name": "CustomScriptExtension",
        "location": "[resourceGroup().location]",
        "properties": {
          "publisher": "Microsoft.Compute",
          "type": "CustomScriptExtension",
          "typeHandlerVersion": "1.9",
          "autoUpgradeMinorVersion": true,
          "forceUpdateTag": "[parameters('forceUpdateTag')]",
          "settings": {
            "fileUris": [
              "https://raw.githubusercontent.com/Azure-Samples/compute-automation-configurations/master/ade-vmss/FormatMBRDisk.ps1"
            ]
          },
          "protectedSettings": {
           "commandToExecute": "powershell -ExecutionPolicy Unrestricted -File FormatMBRDisk.ps1"
          }
        }
      },
      {
        "type": "Microsoft.Compute/virtualMachineScaleSets/extensions",
        "name": "AzureDiskEncryption",
        "location": "[resourceGroup().location]",
        "properties": {
          "provisionAfterExtensions": [
            "CustomScriptExtension"
          ],
          "publisher": "Microsoft.Azure.Security",
          "type": "AzureDiskEncryption",
          "typeHandlerVersion": "2.2",
          "autoUpgradeMinorVersion": true,
          "forceUpdateTag": "[parameters('forceUpdateTag')]",
          "settings": {
            "EncryptionOperation": "EnableEncryption",
            "KeyVaultURL": "[reference(variables('keyVaultResourceId'),'2018-02-14-preview').vaultUri]",
            "KeyVaultResourceId": "[variables('keyVaultResourceID')]",
            "KeyEncryptionKeyURL": "[parameters('keyEncryptionKeyURL')]",
            "KekVaultResourceId": "[variables('keyVaultResourceID')]",
            "KeyEncryptionAlgorithm": "[parameters('keyEncryptionAlgorithm')]",
            "VolumeType": "[parameters('volumeType')]",
            "SequenceVersion": "[parameters('sequenceVersion')]"
          }
        }
      },
    ]
  }
}

If you wish to have Azure Disk Encryption applied before another extension, put the provisionAfterExtensions property in the block of the extension to follow.

Here is an example using "AzureDiskEncryption" followed by "VMDiagnosticsSettings", an extension that provides monitoring and diagnostics capabilities on a Windows-based Azure VM:

"virtualMachineProfile": {
  "extensionProfile": {
    "extensions": [
      {
        "name": "AzureDiskEncryption",
        "type": "Microsoft.Compute/virtualMachineScaleSets/extensions",
        "location": "[resourceGroup().location]",
        "properties": {
          "publisher": "Microsoft.Azure.Security",
          "type": "AzureDiskEncryption",
          "typeHandlerVersion": "2.2",
          "autoUpgradeMinorVersion": true,
          "forceUpdateTag": "[parameters('forceUpdateTag')]",
          "settings": {
            "EncryptionOperation": "EnableEncryption",
            "KeyVaultURL": "[reference(variables('keyVaultResourceId'),'2018-02-14-preview').vaultUri]",
            "KeyVaultResourceId": "[variables('keyVaultResourceID')]",
            "KeyEncryptionKeyURL": "[parameters('keyEncryptionKeyURL')]",
            "KekVaultResourceId": "[variables('keyVaultResourceID')]",
            "KeyEncryptionAlgorithm": "[parameters('keyEncryptionAlgorithm')]",
            "VolumeType": "[parameters('volumeType')]",
            "SequenceVersion": "[parameters('sequenceVersion')]"
          }
        }
      },
      { 
        "name": "Microsoft.Insights.VMDiagnosticsSettings", 
        "type": "extensions", 
        "location": "[resourceGroup().location]", 
        "apiVersion": "2016-03-30", 
        "dependsOn": [ 
          "[concat('Microsoft.Compute/virtualMachines/myVM', copyindex())]" 
        ], 
        "properties": { 
          "provisionAfterExtensions": [
            "AzureDiskEncryption"
          ],
        "publisher": "Microsoft.Azure.Diagnostics", 
          "type": "IaaSDiagnostics", 
          "typeHandlerVersion": "1.5", 
          "autoUpgradeMinorVersion": true, 
          "settings": { 
            "xmlCfg": "[base64(concat(variables('wadcfgxstart'), 
            variables('wadmetricsresourceid'), 
            concat('myVM', copyindex()),
            variables('wadcfgxend')))]", 
            "storageAccount": "[variables('storageName')]" 
          }, 
          "protectedSettings": { 
            "storageAccountName": "[variables('storageName')]", 
            "storageAccountKey": "[listkeys(variables('accountid'), 
              '2015-06-15').key1]", 
            "storageAccountEndPoint": "https://core.windows.net" 
          } 
        } 
      },
    ]
  }
}

For a more in-depth template, see:

Next steps