🌱 Simplify VirtualMachineSnapshot and related APIs (#1196)

This commit refactors the VirtualMachineSnapshot API to use a simple string
field for VM references instead of a complex LocalObjectRef structure, and
resolves field conflicts in the VirtualMachine API.

API Changes:
- Replace VirtualMachineSnapshotSpec.VMRef (LocalObjectRef) with VMName (string)
- Rename VirtualMachine.Spec.CurrentSnapshot to CurrentSnapshotName to resolve
  JSON tag conflict with VirtualMachine.Status.CurrentSnapshot
- Simplify VirtualMachineSnapshotReference to use Name field directly
- VM status now includes the type (managed / unmanaged) and the name
of the snapshot CR)

Changes include:
- Update virtualmachinesnapshot controller to use VMName instead of VMRef
- Update storagepolicyusage and other references in code to handle the
above change.
- Simplify the validation webhook to handle this change
- Add validation to prevent empty/whitespace-only currentSnapshotName
- Maintain VKS/TKG node snapshot prevention logic
- Provider changes to handle this change

Note that I wanted to keep the `spec.currentSnapshot` for the desired
snapshot but that's not possible because two fields with different
type can't have the same JSON tag (spec being a string, and status
being an object).

Author: aruneshpa

api/v1alpha1/zz_generated.conversion.go

@@ -14,7 +14,6 @@ import (
 
 	vmopv1a4common "github.com/vmware-tanzu/vm-operator/api/v1alpha4/common"
 	vmopv1 "github.com/vmware-tanzu/vm-operator/api/v1alpha5"
-	vmopv1common "github.com/vmware-tanzu/vm-operator/api/v1alpha5/common"
 )
 
 func Convert_v1alpha5_VirtualMachineBootstrapCloudInitSpec_To_v1alpha4_VirtualMachineBootstrapCloudInitSpec(
@@ -162,30 +161,29 @@ func Convert_common_LocalObjectRef_To_v1alpha5_VirtualMachineSnapshotReference(
 		return nil
 	}
 
-	// Convert LocalObjectRef to the nested SnapshotReference field
-	out.Reference = &vmopv1common.LocalObjectRef{
-		APIVersion: in.APIVersion,
-		Kind:       in.Kind,
-		Name:       in.Name,
-	}
+	// Convert LocalObjectRef to simplified VirtualMachineSnapshotReference
+	out.Type = vmopv1.VirtualMachineSnapshotReferenceTypeManaged
+	out.Name = in.Name
 
 	return nil
 }
 
 func Convert_v1alpha5_VirtualMachineSnapshotReference_To_common_LocalObjectRef(
 	in *vmopv1.VirtualMachineSnapshotReference, out *vmopv1a4common.LocalObjectRef, s apiconversion.Scope) error {
-	if in == nil || in.Reference == nil {
+	if in == nil {
 		return nil
 	}
 
-	// Convert the nested SnapshotReference back to LocalObjectRef
-	out.APIVersion = in.Reference.APIVersion
-	out.Kind = in.Reference.Kind
-	out.Name = in.Reference.Name
+	// Convert simplified VirtualMachineSnapshotReference back to LocalObjectRef
+	// For managed snapshots, assume it's a VirtualMachineSnapshot resource
+	out.APIVersion = "vmoperator.vmware.com/v1alpha5"
+	out.Kind = "VirtualMachineSnapshot"
+	out.Name = in.Name
 
 	return nil
 }
 
+
 // ConvertTo converts this VirtualMachine to the Hub version.
 func (src *VirtualMachine) ConvertTo(dstRaw ctrlconversion.Hub) error {
 	dst := dstRaw.(*vmopv1.VirtualMachine)

api/v1alpha2/zz_generated.conversion.go

@@ -975,15 +975,14 @@ type VirtualMachineSpec struct {
 
 	// +optional
 
-	// CurrentSnapshot represents the desired snapshot that the VM
+	// CurrentSnapshotName represents the desired snapshot that the VM
 	// should point to. This field can be specified to revert the VM
 	// to a given snapshot. Once the virtual machine has been
 	// successfully reverted to the desired snapshot, the value of
 	// this field is cleared.
 	//
-	// The value of this field must be an existing object of
-	// VirtualMachineSnapshot kind that exists on the API server. All
-	// other values are invalid.
+	// The value of this field must be the name of an existing
+	// VirtualMachineSnapshot resource in the same namespace.
 	//
 	// Reverting a virtual machine to a snapshot rolls back the data
 	// and the configuration of the virtual machine to that of the
@@ -998,7 +997,7 @@ type VirtualMachineSpec struct {
 	// the power state from the snapshot (i.e., powered on). This can
 	// be overridden by specifying the PowerState to PoweredOff in the
 	// VirtualMachineSpec.
-	CurrentSnapshot *vmopv1common.LocalObjectRef `json:"currentSnapshot,omitempty"`
+	CurrentSnapshotName string `json:"currentSnapshotName,omitempty"`
 
 	// +optional
 
@@ -1232,6 +1231,7 @@ type VirtualMachineStatus struct {
 	// +optional
 
 	// CurrentSnapshot describes the observed working snapshot of the VirtualMachine.
+	// This field contains the name of the current snapshot.
 	CurrentSnapshot *VirtualMachineSnapshotReference `json:"currentSnapshot,omitempty"`
 
 	// +optional

api/v1alpha3/zz_generated.conversion.go

@@ -7,8 +7,6 @@ package v1alpha5
 import (
 	"k8s.io/apimachinery/pkg/api/resource"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
-
-	vmopv1common "github.com/vmware-tanzu/vm-operator/api/v1alpha5/common"
 )
 
 const (
@@ -59,9 +57,9 @@ type VirtualMachineSnapshotSpec struct {
 
 	// +optional
 
-	// VMRef represents the name of the virtual machine for which the
+	// VMName represents the name of the virtual machine for which the
 	// snapshot is requested.
-	VMRef *vmopv1common.LocalObjectRef `json:"vmRef,omitempty"`
+	VMName string `json:"vmName,omitempty"`
 }
 
 // QuiesceSpec represents specifications that will be used to quiesce
@@ -201,11 +199,9 @@ type VirtualMachineSnapshotReference struct {
 	// Possible values are: Managed, Unmanaged
 	Type VirtualMachineSnapshotReferenceType `json:"type"`
 
-	// +optional
-
-	// Reference is the reference to the snapshot in the Supervisor.
-	// This should be set only for Managed snapshots.
-	Reference *vmopv1common.LocalObjectRef `json:"reference,omitempty"`
+	// Name is the name of the snapshot resource.  This field is only set
+	// for managed snapshots.
+	Name string `json:"name"`
 }
 
 // VirtualMachineSnapshotStorageStatusRequested describes the observed amount of

api/v1alpha4/virtualmachine_conversion.go

@@ -2151,17 +2151,16 @@ spec:
                               Defaults to true if omitted.
                             type: boolean
                         type: object
-                      currentSnapshot:
+                      currentSnapshotName:
                         description: |-
-                          CurrentSnapshot represents the desired snapshot that the VM
+                          CurrentSnapshotName represents the desired snapshot that the VM
                           should point to. This field can be specified to revert the VM
                           to a given snapshot. Once the virtual machine has been
                           successfully reverted to the desired snapshot, the value of
                           this field is cleared.
 
-                          The value of this field must be an existing object of
-                          VirtualMachineSnapshot kind that exists on the API server. All
-                          other values are invalid.
+                          The value of this field must be the name of an existing
+                          VirtualMachineSnapshot resource in the same namespace.
 
                           Reverting a virtual machine to a snapshot rolls back the data
                           and the configuration of the virtual machine to that of the
@@ -2176,31 +2175,7 @@ spec:
                           the power state from the snapshot (i.e., powered on). This can
                           be overridden by specifying the PowerState to PoweredOff in the
                           VirtualMachineSpec.
-                        properties:
-                          apiVersion:
-                            description: |-
-                              APIVersion defines the versioned schema of this representation of an
-                              object. More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources
-                            type: string
-                          kind:
-                            description: |-
-                              Kind is a string value representing the REST resource this object
-                              represents.
-                              Servers may infer this from the endpoint the client submits requests to.
-                              Cannot be updated.
-                              In CamelCase.
-                              More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds
-                            type: string
-                          name:
-                            description: |-
-                              Name refers to a unique resource in the current namespace.
-                              More info: http://kubernetes.io/docs/user-guide/identifiers#names
-                            type: string
-                        required:
-                        - apiVersion
-                        - kind
-                        - name
-                        type: object
+                        type: string
                       groupName:
                         description: |-
                           GroupName indicates the name of the VirtualMachineGroup to which this