Virtual Machine should use managed OS disk

Medium Azure General vm-virtual-machine-managed-disk

Applies to

Microsoft.Compute/virtualMachines

What CGPulse checks

A resource passes this rule when osDiskManagedDisk must equal true. Anything else is reported as a finding with the evaluated property value attached as evidence.

How to fix it

Migrate to managed disks for built-in encryption, better SLA, and simplified management. In Azure Portal: VM > Disks > Migrate to managed disks. See: https://learn.microsoft.com/en-us/azure/virtual-machines/managed-disks-overview

Careful: Requires VM to be deallocated. All data on unmanaged disks will be migrated

CLI

az vm deallocate --ids "{id}"

Terraform

# Managed disks are the default in azurerm_linux_virtual_machine
resource "azurerm_linux_virtual_machine" "{name}" {
  name                = "{name}"
  resource_group_name = "{rg}"
  location            = var.location
  size                = "Standard_D2s_v5"
  os_disk {
    caching              = "ReadWrite"
    storage_account_type = "Standard_LRS"
  }
  # Unmanaged disks are not supported by this resource
}

Compliance frameworks

Vendor documentation

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