fix(vm): disk re-ordering on re-apply

Signed-off-by: Pavel Boldyrev <627562+bpg@users.noreply.github.com>

proxmoxtf/resource/vm/disk/disk.go

@@ -560,8 +560,11 @@ func Read(
 				}
 			}
 
-			diskList = utils.OrderedListFromMapByKeyValues(diskMap,
-				slices.AppendSeq(make([]string, 0, len(currentDiskMap)), maps.Keys(currentDiskMap)))
+			// Sort keys to ensure deterministic ordering
+			currentKeys := slices.Collect(maps.Keys(currentDiskMap))
+			slices.SortFunc(currentKeys, utils.CompareWithPrefix)
+
+			diskList = utils.OrderedListFromMapByKeyValues(diskMap, currentKeys)
 		} else {
 			diskList = utils.OrderedListFromMap(diskMap)
 		}

proxmoxtf/resource/vm/disk/disk_test.go

@@ -0,0 +1,195 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+package disk
+
+import (
+	"context"
+	"reflect"
+	"testing"
+
+	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
+	"github.com/stretchr/testify/require"
+
+	"github.com/bpg/terraform-provider-proxmox/proxmox"
+	"github.com/bpg/terraform-provider-proxmox/proxmox/nodes/vms"
+	"github.com/bpg/terraform-provider-proxmox/proxmox/types"
+)
+
+// TestDiskOrderingDeterministic tests that disk ordering is deterministic
+// when reading VM disk configuration. This test addresses the issue where
+// disk interfaces (scsi0, scsi1, etc.) would randomly reorder on each
+// terraform apply due to Go's non-deterministic map iteration.
+func TestDiskOrderingDeterministic(t *testing.T) {
+	t.Parallel()
+
+	// Create test schema
+	diskSchema := Schema()
+
+	// Create resource data with multiple disks in a specific order that could be affected by map iteration
+	currentDiskList := []interface{}{
+		map[string]interface{}{
+			mkDiskInterface:   "scsi1", // Intentionally put scsi1 first
+			mkDiskDatastoreID: "local",
+			mkDiskSize:        150,
+			mkDiskSpeed:       []interface{}{},
+		},
+		map[string]interface{}{
+			mkDiskInterface:   "scsi0", // Then scsi0 second
+			mkDiskDatastoreID: "local",
+			mkDiskSize:        50,
+			mkDiskSpeed:       []interface{}{},
+		},
+	}
+
+	// Mock VM disk data from API that matches the currentDiskList
+	// Set Format to avoid API calls in the Read function
+	qcow2Format := "qcow2"
+	diskDeviceObjects := vms.CustomStorageDevices{
+		"scsi0": &vms.CustomStorageDevice{
+			FileVolume: "local:50",
+			Size:       types.DiskSizeFromGigabytes(50),
+			Format:     &qcow2Format,
+		},
+		"scsi1": &vms.CustomStorageDevice{
+			FileVolume: "local:150",
+			Size:       types.DiskSizeFromGigabytes(150),
+			Format:     &qcow2Format,
+		},
+	}
+
+	// Run the ordering logic multiple times to ensure deterministic results
+	const iterations = 10
+
+	results := make([][]interface{}, 0, iterations)
+
+	for range iterations {
+		// Create a new resource data for each iteration
+		resourceData := schema.TestResourceDataRaw(t, diskSchema, map[string]interface{}{
+			MkDisk: currentDiskList,
+		})
+
+		// Call the Read function which contains our fixed ordering logic
+		ctx := context.Background()
+		vmID := 100 // Test VM ID
+
+		var client proxmox.Client = nil // We avoid API calls by setting Format
+
+		nodeName := "test-node"
+		isClone := false
+
+		diags := Read(ctx, resourceData, diskDeviceObjects, vmID, client, nodeName, isClone)
+		require.Empty(t, diags, "Read should not return any diagnostics")
+
+		// Get the resulting disk list
+		diskList := resourceData.Get(MkDisk).([]interface{})
+		results = append(results, diskList)
+	}
+
+	// Verify all results are identical (deterministic ordering)
+	expectedResult := results[0]
+	for i, result := range results {
+		require.True(t, reflect.DeepEqual(expectedResult, result),
+			"Disk ordering should be deterministic across multiple calls. Iteration %d differs from first result", i)
+	}
+
+	// Verify the specific ordering - should be scsi0, then scsi1 (numerical order)
+	require.Len(t, expectedResult, 2, "Should have 2 disks")
+
+	disk0 := expectedResult[0].(map[string]interface{})
+	disk1 := expectedResult[1].(map[string]interface{})
+
+	require.Equal(t, "scsi0", disk0[mkDiskInterface], "First disk should be scsi0")
+	require.Equal(t, 50, disk0[mkDiskSize], "First disk should have size 50")
+
+	require.Equal(t, "scsi1", disk1[mkDiskInterface], "Second disk should be scsi1")
+	require.Equal(t, 150, disk1[mkDiskSize], "Second disk should have size 150")
+}
+
+// TestDiskOrderingVariousInterfaces tests deterministic ordering with various disk interfaces.
+func TestDiskOrderingVariousInterfaces(t *testing.T) {
+	t.Parallel()
+
+	diskSchema := Schema()
+
+	// Test with various interface types in random order
+	currentDiskList := []interface{}{
+		map[string]interface{}{
+			mkDiskInterface:   "virtio2",
+			mkDiskDatastoreID: "local",
+			mkDiskSize:        30,
+			mkDiskSpeed:       []interface{}{},
+		},
+		map[string]interface{}{
+			mkDiskInterface:   "scsi0",
+			mkDiskDatastoreID: "local",
+			mkDiskSize:        10,
+			mkDiskSpeed:       []interface{}{},
+		},
+		map[string]interface{}{
+			mkDiskInterface:   "sata1",
+			mkDiskDatastoreID: "local",
+			mkDiskSize:        20,
+			mkDiskSpeed:       []interface{}{},
+		},
+		map[string]interface{}{
+			mkDiskInterface:   "virtio0",
+			mkDiskDatastoreID: "local",
+			mkDiskSize:        40,
+			mkDiskSpeed:       []interface{}{},
+		},
+	}
+
+	qcow2Format := "qcow2"
+	diskDeviceObjects := vms.CustomStorageDevices{
+		"scsi0":   &vms.CustomStorageDevice{FileVolume: "local:10", Size: types.DiskSizeFromGigabytes(10), Format: &qcow2Format},
+		"sata1":   &vms.CustomStorageDevice{FileVolume: "local:20", Size: types.DiskSizeFromGigabytes(20), Format: &qcow2Format},
+		"virtio2": &vms.CustomStorageDevice{FileVolume: "local:30", Size: types.DiskSizeFromGigabytes(30), Format: &qcow2Format},
+		"virtio0": &vms.CustomStorageDevice{FileVolume: "local:40", Size: types.DiskSizeFromGigabytes(40), Format: &qcow2Format},
+	}
+
+	// Test multiple iterations
+	const iterations = 5
+
+	results := make([][]interface{}, 0, iterations)
+
+	for range iterations {
+		resourceData := schema.TestResourceDataRaw(t, diskSchema, map[string]interface{}{
+			MkDisk: currentDiskList,
+		})
+
+		ctx := context.Background()
+		vmID := 100
+
+		var client proxmox.Client = nil
+
+		nodeName := "test-node"
+		isClone := false
+
+		diags := Read(ctx, resourceData, diskDeviceObjects, vmID, client, nodeName, isClone)
+		require.Empty(t, diags)
+
+		diskList := resourceData.Get(MkDisk).([]interface{})
+		results = append(results, diskList)
+	}
+
+	// Verify deterministic ordering
+	expectedResult := results[0]
+	for i, result := range results {
+		require.True(t, reflect.DeepEqual(expectedResult, result),
+			"Disk ordering should be deterministic for various interfaces. Iteration %d differs", i)
+	}
+
+	// Verify logical ordering: sata1, scsi0, virtio0, virtio2
+	require.Len(t, expectedResult, 4)
+
+	expectedOrder := []string{"sata1", "scsi0", "virtio0", "virtio2"}
+	for i, expectedInterface := range expectedOrder {
+		disk := expectedResult[i].(map[string]interface{})
+		require.Equal(t, expectedInterface, disk[mkDiskInterface],
+			"Disk at position %d should be %s", i, expectedInterface)
+	}
+}

utils/maps.go

@@ -26,7 +26,7 @@ func OrderedListFromMap(inputMap map[string]interface{}) []interface{} {
 		i++
 	}
 
-	slices.SortFunc(keyList, compareWithPrefix)
+	slices.SortFunc(keyList, CompareWithPrefix)
 
 	return OrderedListFromMapByKeyValues(inputMap, keyList)
 }
@@ -36,7 +36,7 @@ func OrderedListFromMap(inputMap map[string]interface{}) []interface{} {
 // - If numbers are equal, falls back to string comparison (preserving digit formatting).
 // - If numeric parsing fails, falls back to string comparison.
 // - If prefixes differ, compares the whole values as strings.
-func compareWithPrefix(a, b string) int {
+func CompareWithPrefix(a, b string) int {
 	prefix := commonPrefix(a, b)
 
 	if prefix != "" {

utils/maps_test.go

@@ -114,7 +114,7 @@ func TestCompareWithPrefix(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			assert.Equalf(t, tt.want, compareWithPrefix(tt.args.a, tt.args.b), "compareWithPrefix(%v, %v)", tt.args.a, tt.args.b)
+			assert.Equalf(t, tt.want, CompareWithPrefix(tt.args.a, tt.args.b), "CompareWithPrefix(%v, %v)", tt.args.a, tt.args.b)
 		})
 	}
 }