fix(vm): Make vm_id computed (#367)

* fix(vm): Make vm_id computed, fix #364

Defaulting vm_id to -1 prevents resources depending on vm_id value.
Make vm_id computed, also update existing vm_id = -1 with correct vm_id.

* update examples to use auto-generated `vm_id`s

---------

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

docs/resources/virtual_environment_container.md

@@ -173,7 +173,7 @@ output "ubuntu_container_public_key" {
 - `template` - (Optional) Whether to create a template (defaults to `false`).
 - `unprivileged` - (Optional) Whether the container runs as unprivileged on
   the host (defaults to `false`).
-- `vm_id` - (Optional) The virtual machine identifier
+- `vm_id` - (Optional) The container identifier
 - `features` - (Optional) The container features
     - `nesting` - (Optional) Whether the container is nested (defaults
       to `false`)

example/resource_virtual_environment_container.tf

@@ -39,7 +39,8 @@ resource "proxmox_virtual_environment_container" "example_template" {
 
   pool_id  = proxmox_virtual_environment_pool.example.id
   template = true
-  vm_id    = 2042
+
+  // use auto-generated vm_id
 
   tags = [
     "container",

example/resource_virtual_environment_vm.tf

@@ -72,7 +72,8 @@ resource "proxmox_virtual_environment_vm" "example_template" {
   serial_device {}
 
   template = true
-  vm_id    = 2040
+
+  // use auto-generated vm_id
 }
 
 resource "proxmox_virtual_environment_vm" "example" {

proxmoxtf/resource/vm.go

@@ -103,7 +103,6 @@ const (
 	dvResourceVirtualEnvironmentVMVGAEnabled                        = true
 	dvResourceVirtualEnvironmentVMVGAMemory                         = 16
 	dvResourceVirtualEnvironmentVMVGAType                           = "std"
-	dvResourceVirtualEnvironmentVMVMID                              = -1
 	dvResourceVirtualEnvironmentVMSCSIHardware                      = "virtio-scsi-pci"
 
 	maxResourceVirtualEnvironmentVMAudioDevices   = 1
@@ -1208,11 +1207,12 @@ func VM() *schema.Resource {
 				MinItems: 0,
 			},
 			mkResourceVirtualEnvironmentVMVMID: {
-				Type:             schema.TypeInt,
-				Description:      "The VM identifier",
-				Optional:         true,
-				ForceNew:         true,
-				Default:          dvResourceVirtualEnvironmentVMVMID,
+				Type:        schema.TypeInt,
+				Description: "The VM identifier",
+				Optional:    true,
+				Computed:    true,
+				// "ForceNew: true" handled in CustomizeDiff, making sure VMs with legacy configs with vm_id = -1
+				// do not require re-creation.
 				ValidateDiagFunc: getVMIDValidator(),
 			},
 			mkResourceVirtualEnvironmentVMSCSIHardware: {
@@ -1249,6 +1249,16 @@ func VM() *schema.Resource {
 						d.HasChange(mkResourceVirtualEnvironmentVMNetworkDevice)
 				},
 			),
+			customdiff.ForceNewIf(
+				mkResourceVirtualEnvironmentVMVMID,
+				func(ctx context.Context, d *schema.ResourceDiff, meta interface{}) bool {
+					newValue := d.Get(mkResourceVirtualEnvironmentVMVMID)
+
+					// 'vm_id' is ForceNew, except when changing 'vm_id' to existing correct id
+					// (automatic fix from -1 to actual vm_id must not re-create VM)
+					return strconv.Itoa(newValue.(int)) != d.Id()
+				},
+			),
 		),
 	}
 }
@@ -1284,14 +1294,21 @@ func vmCreateClone(ctx context.Context, d *schema.ResourceData, m interface{}) d
 	tags := d.Get(mkResourceVirtualEnvironmentVMTags).([]interface{})
 	nodeName := d.Get(mkResourceVirtualEnvironmentVMNodeName).(string)
 	poolID := d.Get(mkResourceVirtualEnvironmentVMPoolID).(string)
-	vmID := d.Get(mkResourceVirtualEnvironmentVMVMID).(int)
+	vmIDUntyped, hasVMID := d.GetOk(mkResourceVirtualEnvironmentVMVMID)
+	vmID := vmIDUntyped.(int)
 
-	if vmID == -1 {
+	if !hasVMID {
 		vmIDNew, err := api.Cluster().GetVMID(ctx)
 		if err != nil {
 			return diag.FromErr(err)
 		}
+
 		vmID = *vmIDNew
+		err = d.Set(mkResourceVirtualEnvironmentVMVMID, vmID)
+
+		if err != nil {
+			return diag.FromErr(err)
+		}
 	}
 
 	fullCopy := types.CustomBool(cloneFull)
@@ -1928,15 +1945,21 @@ func vmCreateCustom(ctx context.Context, d *schema.ResourceData, m interface{})
 		return diag.FromErr(err)
 	}
 
-	vmID := d.Get(mkResourceVirtualEnvironmentVMVMID).(int)
+	vmIDUntyped, hasVMID := d.GetOk(mkResourceVirtualEnvironmentVMVMID)
+	vmID := vmIDUntyped.(int)
 
-	if vmID == -1 {
+	if !hasVMID {
 		vmIDNew, e := api.Cluster().GetVMID(ctx)
 		if e != nil {
 			return diag.FromErr(e)
 		}
 
 		vmID = *vmIDNew
+		e = d.Set(mkResourceVirtualEnvironmentVMVMID, vmID)
+
+		if e != nil {
+			return diag.FromErr(e)
+		}
 	}
 
 	var memorySharedObject *vms.CustomSharedMemory
@@ -2812,6 +2835,18 @@ func vmReadCustom(
 		return diags
 	}
 
+	// Fix terraform.tfstate, by replacing '-1' (the old default value) with actual vm_id value
+	if storedVMID := d.Get(mkResourceVirtualEnvironmentVMVMID).(int); storedVMID == -1 {
+		diags = append(diags, diag.Diagnostic{
+			Severity: diag.Warning,
+			Summary: fmt.Sprintf("VM %s has stored legacy vm_id %d, setting vm_id to its correct value %d.",
+				d.Id(), storedVMID, vmID),
+		})
+
+		err = d.Set(mkResourceVirtualEnvironmentVMVMID, vmID)
+		diags = append(diags, diag.FromErr(err)...)
+	}
+
 	nodeName := d.Get(mkResourceVirtualEnvironmentVMNodeName).(string)
 	clone := d.Get(mkResourceVirtualEnvironmentVMClone).([]interface{})