How to Import an Azure Managed Disk into Terraform

Import Azure Managed Disk with Terraback (recommended)

Terraback reverse-engineers your live infrastructure: it reads the Azure Compute resource with read-only credentials, generates the HCL, and produces the exact import block. Two commands take you from a live Azure Managed Disk to managed Terraform.

terraback scan all azure --subscription-id YOUR_ID

terraback azure import --method bulk

The Terraform import block

Terraback emits a Terraform 1.5+ import block like the one below. Because the block lives in your configuration, the import is reviewable in a pull request and repeatable across environments.

import {
  to = azurerm_managed_disk.data
  id = "/subscriptions/00000000-0000-0000-0000-000000000000/resourceGroups/prod-rg/providers/Microsoft.Compute/disks/data-disk-01"
}

Example azurerm_managed_disk configuration

Here is a realistic Azure Managed Disk block. Terraback generates a fuller version from your actual resource attributes; this is a minimal, valid starting point.

resource "azurerm_managed_disk" "data" {
  name                 = "data-disk-01"
  resource_group_name  = "prod-rg"
  location             = "eastus"
  storage_account_type = "Premium_LRS"
  create_option        = "Empty"
  disk_size_gb         = 256
}

Gotchas when importing a Azure Managed Disk

• create_option is required and immutable; an existing disk imports with whatever option created it (Empty, Copy, FromImage, Import).
• Disk-to-VM attachment is a separate azurerm_virtual_machine_data_disk_attachment resource, not part of the disk.
• Shrinking disk_size_gb is not allowed; you can only grow a managed disk.
• OS disks created by a VM are best left managed through the VM's os_disk block rather than imported standalone.

Doing it manually with terraform import

The native approach is to write the azurerm_managed_disk block by hand, then run terraform import azurerm_managed_disk.example <import-id> for every resource, one at a time. That works for a handful of resources, but it does not scale: you author all the HCL yourself and repeat the command for each item. Terraback generates the HCL and the import blocks for your whole account in one pass.

Import other Azure resources