Install Steam on persistent data disk that is never destroyed by terraform

main.tf

@@ -54,6 +54,19 @@ resource "azurerm_network_interface" "vm_nic" {
   }
 }
 
+resource "azurerm_managed_disk" "data_disk" {
+  name                 = "${var.prefix}-winvm-datadisk"
+  location             = azurerm_resource_group.rg.location
+  resource_group_name  = azurerm_resource_group.rg.name
+  storage_account_type = "Premium_LRS"
+  create_option        = "Empty"
+  disk_size_gb         = var.datadisk_size_gb
+
+  lifecycle {
+    prevent_destroy = true
+  }
+}
+
 resource "random_password" "admin_password" {
   length  = 16
   special = false
@@ -65,6 +78,8 @@ resource "azurerm_windows_virtual_machine" "vm" {
   resource_group_name = azurerm_resource_group.rg.name
   location            = azurerm_resource_group.rg.location
   size                = var.vm_size
+  priority            = var.vm_priority
+  eviction_policy     = var.vm_priority == "Spot" ? "Deallocate" : null
 
   admin_username = var.vm_admin_username
   admin_password = random_password.admin_password.result
@@ -86,6 +101,13 @@ resource "azurerm_windows_virtual_machine" "vm" {
   }
 }
 
+resource "azurerm_virtual_machine_data_disk_attachment" "data_disk_attachment" {
+  managed_disk_id    = azurerm_managed_disk.data_disk.id
+  virtual_machine_id = azurerm_windows_virtual_machine.vm.id
+  lun                = var.datadisk_lun
+  caching            = "ReadWrite"
+}
+
 resource "azurerm_virtual_machine_extension" "provision_software" {
   name                 = "provision-software"
   virtual_machine_id   = azurerm_windows_virtual_machine.vm.id
@@ -93,9 +115,11 @@ resource "azurerm_virtual_machine_extension" "provision_software" {
   type                 = "CustomScriptExtension"
   type_handler_version = "1.10"
 
+  depends_on = [azurerm_virtual_machine_data_disk_attachment.data_disk_attachment]
+
   protected_settings = <<SETTINGS
   {    
-    "commandToExecute": "powershell -command \"[System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String('${base64encode(templatefile("${path.module}/scripts/provision-software.ps1.tpl", {tailscale_authkey = var.tailscale_authkey}))}')) | Out-File -filepath provision-software.ps1\" && powershell -ExecutionPolicy Unrestricted -File provision-software.ps1"
+    "commandToExecute": "powershell -command \"[System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String('${base64encode(templatefile("${path.module}/scripts/provision-software.ps1.tpl", { tailscale_authkey = var.tailscale_authkey, datadisk_lun = var.datadisk_lun, datadisk_drive_letter = var.datadisk_drive_letter }))}')) | Out-File -filepath provision-software.ps1\" && powershell -ExecutionPolicy Unrestricted -File provision-software.ps1"
   }
   SETTINGS
-}
+}

scripts/provision-software.ps1.tpl

@@ -1,3 +1,8 @@
+$ErrorActionPreference = 'Stop'
+
+$DataDiskLun = '${datadisk_lun}'
+$DataDiskDriveLetter = '${datadisk_drive_letter}'
+
 $TailscaleUri = 'https://pkgs.tailscale.com/stable/tailscale-setup-1.88.3-amd64.msi'
 $TailscaleMsi = 'tailscale.msi'
 $TailscaleInstalledExe = 'C:\Program Files\Tailscale\tailscale.exe'
@@ -15,6 +20,20 @@ $SunshineInstallerExe = 'sunshine-installer.exe'
 $SteamInstallerUri = 'https://cdn.fastly.steamstatic.com/client/installer/SteamSetup.exe'
 $SteamInstallerExe = 'steam-installer.exe'
 
+Write-Host "Setting up data disk"
+
+$DataDisk = Get-Disk | Where-Object { $_.Location -Like "*LUN $DataDiskLun*" }
+if ($DataDisk.PartitionStyle -eq 'raw') {
+    Initialize-Disk -UniqueId $DataDisk.UniqueId -PartitionStyle GPT
+    New-Partition -DiskId $DataDisk.UniqueId -UseMaximumSize -DriveLetter $DataDiskDriveLetter
+    Format-Volume -DriveLetter $DataDiskDriveLetter -FileSystem NTFS -NewFileSystemLabel DataDisk -Confirm:$False
+} else {
+    $Partition = Get-Partition -DiskNumber $DataDisk.DiskNumber | Where-Object { $_.Type -eq "Basic" }
+    Set-Partition -InputObject $Partition -NewDriveLetter $DataDiskDriveLetter
+}
+
+Write-Host "Done setting up data disk"
+
 Write-Host "Provisioning software"
 
 ##
@@ -66,11 +85,17 @@ Write-Host 'Done installing Sunshine, configure at https://localhost:47990/'
 ##
 # Steam
 Write-Host "Installing Steam"
-Write-Host "Downloading Steam installer from $SteamInstallerUri to $SteamInstallerExe"
-Invoke-WebRequest -UseBasicParsing -Uri $SteamInstallerUri -OutFile $SteamInstallerExe
 
-Write-Host "Installing Steam from $SteamInstallerExe"
-Start-Process $SteamInstallerExe -ArgumentList '/S' -Wait -NoNewWindow -PassThru
+if(Test-Path "$($DataDiskDriveLetter):\Steam\Steam.exe") {
+    Write-Host "Steam is already installed, skipping"
+} else {
+    Write-Host "Downloading Steam installer from $SteamInstallerUri to $SteamInstallerExe"
+    Invoke-WebRequest -UseBasicParsing -Uri $SteamInstallerUri -OutFile $SteamInstallerExe
+
+    Write-Host "Installing Steam from $SteamInstallerExe"
+    New-Item -Path "$($DataDiskDriveLetter):\" -Name 'Steam' -ItemType Directory
+    Start-Process $SteamInstallerExe -ArgumentList '/S', "/D=$($DataDiskDriveLetter):\Steam" -Wait -NoNewWindow -PassThru
+}
 
 Write-Host 'Done installing Steam'
 

variables.tf

@@ -59,12 +59,36 @@ variable "vm_size" {
   default     = "Standard_NG16ads_V620_v1"
 }
 
+variable "vm_priority" {
+  description = "Priority of the VM, can be Regular or Spot. Spot is cheaper, but can be evicted at any time"
+  type        = string
+  default     = "Regular"
+}
+
 variable "vm_admin_username" {
   description = "VM admin username, password will be generated randomly"
   type        = string
   default     = "jona"
 }
 
+variable "datadisk_size_gb" {
+  description = "Size of the persisted datadisk in gb"
+  type        = number
+  default     = 1024
+}
+
+variable "datadisk_lun" {
+  description = "Location identifier, this is used to identify the disk within the VM"
+  type        = string
+  default     = "10"
+}
+
+variable "datadisk_drive_letter" {
+  description = "Drive letter to mount the datadisk to"
+  type        = string
+  default     = "Z"
+}
+
 variable "tailscale_authkey" {
   description = "Tailscale auth key for unattended login"
   type        = string