Use a Custom Script Extension to Sysprep an Azure VM

Hi All,

I’ve been in a situation where I want to run sysprep on a Azure VM to create an image, hopefully without needing to login / connect directly to the VM. I thought that this was an opportunity to learn about custom script extensions. (for use in other situations as well)


in summary, I created a powershell script file, and saved it to a new file ‘sysprep.ps1’:

write-output "Sysprep Script Run, parameter 'runSysprep': $runSysprep"

  write-output "starting Sysprep"
  Start-Process -FilePath C:\Windows\System32\Sysprep\Sysprep.exe -ArgumentList '/generalize /oobe /shutdown /quiet'
  write-output "started Sysprep"
  write-output "skipping Sysprep"


I then uploaded this to a storage account, set the security on the container to ‘blob’ (there’s nothing sensitive in that script), then ran the following:

$VMName =  'vmName'
$VMRG = 'vmResourceGroup'
$VMLocation = 'AustraliaEast'
$ExtensionName = 'runsysprep'
$Scripturi = 'https://<storageAccountName>'
Set-AzureRmVMCustomScriptExtension -FileUri $ScriptURI -ResourceGroupName  $VMRG -VMName $VMName -Name $ExtensionName -Location $VMLocation -run './scripts/sysprep.ps1' -Argument '-runSysprep'


This gave the output:

RequestId IsSuccessStatusCode StatusCode ReasonPhrase
--------- ------------------- ---------- ------------
                         True         OK OK

To see the output messages from the script that was run:

$status = Get-AzureRmVMDiagnosticsExtension -ResourceGroupName $VMRG -VMName $VMName -Name $ExtensionName -Status

This displayed the output that was expected:

Sysprep Script Run, parameter 'runSysprep': True\nstarting Sysprep\nstarted Sysprep


A short time later, the VM is shutdown (but is still allocated & incurring charges), so i then shutdown the VM:

Stop-AzureRmVM -Name $VMName -ResourceGroupName $VMRG  -force


As with everything I post about, please give comments / questions on my approach /methods


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