fix: add vm to existing vm group

CHANGELOG.md

@@ -1,5 +1,12 @@
 # <!-- markdownlint-disable first-line-h1 no-inline-html -->
 
+## 2.9.2 (nNot Released)
+
+BUG FIX:
+* `resource/vsphere_compute_cluster_vm_group`: Updates resource to allow for additional virtual
+  machines to be adding or removed from a VM Group. Must be ran in conjunction with and import.
+  ([#2260]https://github.com/hashicorp/terraform-provider-vsphere/pull/2260)
+
 ## 2.9.1 (September 9, 2024)
 
 BUG FIX:

vsphere/resource_vsphere_compute_cluster_vm_group.go

@@ -4,6 +4,7 @@
 package vsphere
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -63,6 +64,17 @@ func resourceVSphereComputeClusterVMGroupCreate(d *schema.ResourceData, meta int
 		return err
 	}
 
+	// Check if the VM group already exists
+	exists, err := resourceVSphereComputeClusterVMGroupFindEntry(cluster, name)
+	if err != nil {
+		return err
+	}
+
+	if exists != nil {
+		log.Printf("[DEBUG] %s: VM group already exists, calling update", exists.Name)
+		return resourceVSphereComputeClusterVMGroupUpdate(d, meta)
+	}
+
 	info, err := expandClusterVMGroup(d, meta, name)
 	if err != nil {
 		return err
@@ -140,17 +152,82 @@ func resourceVSphereComputeClusterVMGroupUpdate(d *schema.ResourceData, meta int
 		return err
 	}
 
-	info, err := expandClusterVMGroup(d, meta, name)
+	// Retrieve the existing VM group information.
+	existingGroup, err := getCurrentVMsInGroup(cluster, name)
+	if err != nil {
+		return err
+	}
+
+	// Check if existingGroup is nil.
+	if existingGroup == nil {
+		return fmt.Errorf("VM group %s not found", name)
+	}
+
+	// Expand the new VM group information.
+	newInfo, err := expandClusterVMGroup(d, meta, name)
 	if err != nil {
 		return err
 	}
+
+	// Convert existing and new virtual machines to string slices for diffVmGroup.
+	existingVMs := make([]string, len(existingGroup.Vm))
+	for i, vm := range existingGroup.Vm {
+		existingVMs[i] = vm.Value
+	}
+
+	newVMs := make([]string, len(newInfo.Vm))
+	for i, vm := range newInfo.Vm {
+		newVMs[i] = vm.Value
+	}
+
+	// Use diffVmGroup to find added and removed virtual machines from virtual machine group.
+	addedVMs, removedVMs := diffVmGroup(existingVMs, newVMs)
+
+	// Convert addedVMs and removedVMs back to ManagedObjectReference slices.
+	addedVMRefs := make([]types.ManagedObjectReference, len(addedVMs))
+	for i, vm := range addedVMs {
+		addedVMRefs[i] = types.ManagedObjectReference{
+			Type:  "VirtualMachine",
+			Value: vm,
+		}
+	}
+
+	removedVMRefs := make([]types.ManagedObjectReference, len(removedVMs))
+	for i, vm := range removedVMs {
+		removedVMRefs[i] = types.ManagedObjectReference{
+			Type:  "VirtualMachine",
+			Value: vm,
+		}
+	}
+
+	// Merge existing virtual machines with added virtual machines and remove duplicates.
+	mergedVMs := append(existingGroup.Vm, addedVMRefs...)
+	vmMap := make(map[types.ManagedObjectReference]bool)
+	for _, vm := range mergedVMs {
+		vmMap[vm] = true
+	}
+	for _, vm := range removedVMRefs {
+		delete(vmMap, vm)
+	}
+	uniqueVMs := make([]types.ManagedObjectReference, 0, len(vmMap))
+	for vm := range vmMap {
+		uniqueVMs = append(uniqueVMs, vm)
+	}
+
+	if len(uniqueVMs) == 0 {
+		return fmt.Errorf("the resultant set of virtual machines in the vm group cannot be empty")
+	}
+
+	// Update the VM group information with the merged list.
+	newInfo.Vm = uniqueVMs
+
 	spec := &types.ClusterConfigSpecEx{
 		GroupSpec: []types.ClusterGroupSpec{
 			{
 				ArrayUpdateSpec: types.ArrayUpdateSpec{
 					Operation: types.ArrayUpdateOperationEdit,
 				},
-				Info: info,
+				Info: newInfo,
 			},
 		},
 	}
@@ -397,3 +474,41 @@ func resourceVSphereComputeClusterVMGroupClient(meta interface{}) (*govmomi.Clie
 	}
 	return client, nil
 }
+
+func diffVmGroup(oldVMs, newVMs []string) ([]string, []string) {
+	oldVMMap := make(map[string]bool)
+	for _, vm := range oldVMs {
+		oldVMMap[vm] = true
+	}
+
+	var addedVMs, removedVMs []string
+	for _, vm := range newVMs {
+		if !oldVMMap[vm] {
+			addedVMs = append(addedVMs, vm)
+		}
+		delete(oldVMMap, vm)
+	}
+
+	for vm := range oldVMMap {
+		removedVMs = append(removedVMs, vm)
+	}
+
+	return addedVMs, removedVMs
+}
+
+// getCurrentVMsInGroup retrieves the current VMs in the specified VM group from the vSphere cluster.
+func getCurrentVMsInGroup(cluster *object.ClusterComputeResource, groupName string) (*types.ClusterVmGroup, error) {
+	ctx := context.TODO()
+	groups, err := cluster.Configuration(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, group := range groups.Group {
+		if vmGroup, ok := group.(*types.ClusterVmGroup); ok && vmGroup.Name == groupName {
+			return vmGroup, nil
+		}
+	}
+
+	return nil, fmt.Errorf("VM group %s not found", groupName)
+}

website/docs/r/compute_cluster_vm_group.html.markdown

@@ -108,6 +108,11 @@ resource. Make sure your names are unique across both resources.
 
 [tf-vsphere-cluster-host-group-resource]: /docs/providers/vsphere/r/compute_cluster_host_group.html
 
+~> **NOTE:** To update a existing VM group, you must first import the group with `import` command in
+[Importing](#importing) section. When importing a VM group, validate that all virtual machines that
+need to be in the group are included in the `virtual_machine_ids`; otherwise, any virtual machines
+that are not in `virtual_machine_ids` the included will be removed from the group.
+
 ## Attribute Reference
 
 The only attribute this resource exports is the `id` of the resource, which is