fix(disk): restore updating boot disk.

docs/resources/virtual_environment_vm.md

@@ -305,7 +305,7 @@ output "ubuntu_vm_public_key" {
           `proxmox_virtual_environment_download_file` resource. *Deprecated*, use `import_from` instead.
     - `import_from` - (Optional) The file ID for a disk image to import into VM. The image must be of `import` content type.
        The ID format is `<datastore_id>:import/<file_name>`, for example `local:import/centos8.qcow2`. Can be also taken from
-       `proxmox_virtual_environment_download_file` resource.
+       a disk replacement operation, which will require a VM reboot. Your original disks will remain as detached disks.
     - `interface` - (Required) The disk interface for Proxmox, currently `scsi`,
         `sata` and `virtio` interfaces are supported. Append the disk index at
         the end, for example, `virtio0` for the first virtio disk, `virtio1` for

proxmoxtf/resource/vm/disk/disk.go

@@ -549,13 +549,19 @@ func Read(
 
 		if len(currentDiskList) > 0 {
 			currentDiskMap := utils.MapResourcesByAttribute(currentDiskList, mkDiskInterface)
-			// copy import_from from the current disk if it exists
+			// copy import_from and size from the current disk if it exists
 			for k, v := range currentDiskMap {
 				if disk, ok := v.(map[string]any); ok {
-					if importFrom, ok := disk[mkDiskImportFrom].(string); ok && importFrom != "" {
-						if _, exists := diskMap[k]; exists {
+					if _, exists := diskMap[k]; exists {
+						if importFrom, ok := disk[mkDiskImportFrom].(string); ok && importFrom != "" {
 							diskMap[k].(map[string]any)[mkDiskImportFrom] = importFrom
 						}
+						// preserve size from state when API returns zero size (for disks with import_from or file_id)
+						if currentSize, ok := disk[mkDiskSize].(int); ok && currentSize > 0 {
+							if apiSize, ok := diskMap[k].(map[string]any)[mkDiskSize].(int64); ok && apiSize == 0 {
+								diskMap[k].(map[string]any)[mkDiskSize] = currentSize
+							}
+						}
 					}
 				}
 			}
@@ -583,8 +589,9 @@ func Update(
 	planDisks vms.CustomStorageDevices,
 	currentDisks vms.CustomStorageDevices,
 	updateBody *vms.UpdateRequestBody,
-) (bool, error) {
+) (bool, bool, error) {
 	rebootRequired := false
+	shutdownBeforeUpdate := false
 
 	if d.HasChange(MkDisk) {
 		for iface, disk := range planDisks {
@@ -596,7 +603,7 @@ func Update(
 					// only disks with defined file ID are custom image disks that need to be created via import.
 					err := createCustomDisk(ctx, client, nodeName, vmID, iface, *disk)
 					if err != nil {
-						return false, fmt.Errorf("creating custom disk: %w", err)
+						return false, false, fmt.Errorf("creating custom disk: %w", err)
 					}
 				} else {
 					// otherwise this is a blank disk that can be added directly via update API
@@ -612,7 +619,7 @@ func Update(
 				tmp = currentDisks[iface]
 			default:
 				// something went wrong
-				return false, fmt.Errorf("missing device %s", iface)
+				return false, false, fmt.Errorf("missing device %s", iface)
 			}
 
 			if tmp == nil || disk == nil {
@@ -624,8 +631,12 @@ func Update(
 				tmp.AIO = disk.AIO
 			}
 
-			// Never send ImportFrom for existing disks - it triggers re-import which fails for boot disks
-			// ImportFrom is only for initial disk creation, not updates
+			if disk.ImportFrom != nil && *disk.ImportFrom != "" {
+				shutdownBeforeUpdate = true
+				tmp.DatastoreID = disk.DatastoreID
+				tmp.ImportFrom = disk.ImportFrom
+				tmp.Size = disk.Size
+			}
 
 			tmp.Backup = disk.Backup
 			tmp.BurstableReadSpeedMbps = disk.BurstableReadSpeedMbps
@@ -647,5 +658,5 @@ func Update(
 		}
 	}
 
-	return rebootRequired, nil
+	return shutdownBeforeUpdate, rebootRequired, nil
 }

proxmoxtf/resource/vm/disk/disk_test.go

@@ -210,19 +210,23 @@ func TestDiskDevicesEqual(t *testing.T) {
 	size2 := types.DiskSizeFromGigabytes(10)
 	datastore1 := "local"
 	datastore2 := "local"
+	importFrom1 := "local:import/test.qcow2"
+	importFrom2 := "local:import/test.qcow2"
 
 	disk1 := &vms.CustomStorageDevice{
 		AIO:         &aio1,
 		Cache:       &cache1,
 		Size:        size1,
 		DatastoreID: &datastore1,
+		ImportFrom:  &importFrom1,
 	}
 
 	disk2 := &vms.CustomStorageDevice{
 		AIO:         &aio2,
 		Cache:       &cache2,
 		Size:        size2,
 		DatastoreID: &datastore2,
+		ImportFrom:  &importFrom2,
 	}
 
 	// Test identical disks
@@ -247,6 +251,17 @@ func TestDiskDevicesEqual(t *testing.T) {
 		DatastoreID: &datastore2,
 	}
 	require.False(t, disk1.Equals(disk2SizeChanged))
+
+	// Test different ImportFrom values
+	importFrom2Changed := "local:import/test2.qcow2"
+	disk2ImportFromChanged := &vms.CustomStorageDevice{
+		AIO:         &aio2,
+		Cache:       &cache2,
+		Size:        size2,
+		ImportFrom:  &importFrom2Changed,
+		DatastoreID: &datastore2,
+	}
+	require.False(t, disk1.Equals(disk2ImportFromChanged))
 }
 
 // TestDiskUpdateSkipsUnchangedDisks tests that the Update function only updates changed disks.
@@ -339,8 +354,9 @@ func TestDiskUpdateSkipsUnchangedDisks(t *testing.T) {
 	require.NoError(t, err)
 
 	// Call the Update function
-	_, err = Update(ctx, client, nodeName, vmID, resourceData, planDisks, currentDisks, updateBody)
+	shutdownBeforeUpdate, _, err := Update(ctx, client, nodeName, vmID, resourceData, planDisks, currentDisks, updateBody)
 	require.NoError(t, err)
+	require.False(t, shutdownBeforeUpdate)
 
 	// Check that only the changed disk (scsi1) is in the update body
 	// scsi0 should NOT be in the update body since it hasn't changed
@@ -350,6 +366,59 @@ func TestDiskUpdateSkipsUnchangedDisks(t *testing.T) {
 	// This prevents the "can't unplug bootdisk 'scsi0'" error
 	// Note: We can't directly inspect the updateBody content in this test framework,
 	// but the fact that no error occurred means the logic worked correctly
+
+	// Create plan disks (what terraform wants)
+	importFrom2 := "local:import/test2.qcow2"
+	planDisks2 := vms.CustomStorageDevices{
+		"scsi0": &vms.CustomStorageDevice{
+			Size:        types.DiskSizeFromGigabytes(10), // Same as current
+			DatastoreID: &datastoreID,
+			ImportFrom:  &importFrom2, // Different Import file.
+		},
+		"scsi1": &vms.CustomStorageDevice{
+			Size:        types.DiskSizeFromGigabytes(5), // Same as current
+			DatastoreID: &datastoreID,
+		},
+	}
+
+	// Mock update body to capture what gets sent to the API
+	updateBody2 := &vms.UpdateRequestBody{}
+
+	// Force HasChange to return true by setting old and new values
+	err = resourceData.Set(MkDisk, []any{
+		map[string]any{
+			mkDiskInterface:   "scsi1",
+			mkDiskDatastoreID: "local",
+			mkDiskSize:        5, // Old size
+			mkDiskSpeed:       []any{},
+		},
+	})
+	require.NoError(t, err)
+
+	err = resourceData.Set(MkDisk, []any{
+		map[string]any{
+			mkDiskInterface:   "scsi1",
+			mkDiskDatastoreID: "local",
+			mkDiskSize:        20, // New size
+			mkDiskSpeed:       []any{},
+		},
+	})
+	require.NoError(t, err)
+
+	// Call the Update function
+	shutdownBeforeUpdate, _, err = Update(ctx, client, nodeName, vmID, resourceData, planDisks2, currentDisks, updateBody2)
+	require.NoError(t, err)
+	require.True(t, shutdownBeforeUpdate)
+
+	// Check that only the changed disk (scsi1) is in the update body
+	// scsi0 should NOT be in the update body since it hasn't changed
+	require.NotNil(t, updateBody2)
+	require.Contains(t, updateBody2.CustomStorageDevices, "scsi0", "Update body should contain the changed disk scsi0")
+	require.NotContains(t, updateBody2.CustomStorageDevices, "scsi1", "Update body should not contain the unchanged disk scsi1")
+	require.Equal(t, importFrom2, *updateBody2.CustomStorageDevices["scsi0"].ImportFrom)
+
+	// The update body should only contain scsi0, not scsi1
+	// Note: We can't directly inspect the updateBody content in this test framework,
 }
 
 func TestDiskDeletionDetectionInGetDiskDeviceObjects(t *testing.T) {

proxmoxtf/resource/vm/vm.go

@@ -5575,11 +5575,17 @@ func vmUpdate(ctx context.Context, d *schema.ResourceData, m any) diag.Diagnosti
 		}
 	}
 
-	rr, err := disk.Update(ctx, client, nodeName, vmID, d, planDisks, allDiskInfo, updateBody)
+	stoppedBeforeUpdate, rr, err := disk.Update(ctx, client, nodeName, vmID, d, planDisks, allDiskInfo, updateBody)
 	if err != nil {
 		return diag.FromErr(err)
 	}
 
+	if stoppedBeforeUpdate {
+		if er := vmShutdown(ctx, vmAPI, d); er != nil {
+			return er
+		}
+	}
+
 	rebootRequired = rebootRequired || rr
 
 	// Prepare the new efi disk configuration.
@@ -5610,7 +5616,6 @@ func vmUpdate(ctx context.Context, d *schema.ResourceData, m any) diag.Diagnosti
 	}
 
 	// Prepare the new cloud-init configuration.
-	stoppedBeforeUpdate := false
 	cloudInitRebuildRequired := false
 
 	if d.HasChange(mkInitialization) {
@@ -5657,8 +5662,10 @@ func vmUpdate(ctx context.Context, d *schema.ResourceData, m any) diag.Diagnosti
 			if mustMove || mustChangeDatastore || existingInterface == "" {
 				// CloudInit must be moved, either from a device to another or from a datastore
 				// to another (or both). This requires the VM to be stopped.
-				if er := vmShutdown(ctx, vmAPI, d); er != nil {
-					return er
+				if !stoppedBeforeUpdate {
+					if er := vmShutdown(ctx, vmAPI, d); er != nil {
+						return er
+					}
 				}
 
 				if er := deleteIdeDrives(ctx, vmAPI, initializationInterface, existingInterface); er != nil {
@@ -5945,7 +5952,7 @@ func vmUpdate(ctx context.Context, d *schema.ResourceData, m any) diag.Diagnosti
 			if diags := vmStart(ctx, vmAPI, d); diags != nil {
 				return diags
 			}
-		} else {
+		} else if !stoppedBeforeUpdate {
 			if er := vmShutdown(ctx, vmAPI, d); er != nil {
 				return er
 			}