feat: implement auto-population of AWSMachineTemplate capacity and nodeInfo

Add AWSMachineTemplateReconciler to automatically populate capacity and node
info fields by querying AWS EC2 API. This completes the autoscaling from zero
implementation by ensuring the required metadata is available without manual
configuration.

Changes include:
- Add NodeInfo struct with Architecture and OperatingSystem fields to AWSMachineTemplate status
- Implement controller that queries EC2 API for instance type specifications
- Auto-populate CPU, memory, pods, and ephemeral storage capacity
- Auto-detect architecture (amd64/arm64) and OS (linux/windows) from AMI
- Add conversion logic for backward compatibility with v1beta1
- Enable status subresource on AWSMachineTemplate CRD
- Add comprehensive unit tests (351 lines) covering various scenarios
- Add RBAC permissions for controller operations

The controller automatically populates these fields when an AWSMachineTemplate
is created or updated, eliminating the need for manual configuration and
enabling Cluster Autoscaler to make informed scaling decisions from zero nodes.

Related: https://github.com/kubernetes-sigs/cluster-api/blob/main/docs/proposals/20210310-opt-in-autoscaling-from-zero.md

Squashed from 5 commits:
- 9a92a43 Implement autoscaling from zero by auto-populating AWSMachineTemplate capacity
- 86fe072 add AWSMachineTemplate NodeInfo
- ddaf62c Fix review comments
- 4ea52c8 Fix review comments 2
- b398ffc Fix review comments 3

Author: LiangquanLi930

api/v1beta1/awsmachine_conversion.go

@@ -136,6 +136,9 @@ func (r *AWSMachineTemplate) ConvertTo(dstRaw conversion.Hub) error {
 		}
 	}
 
+	// Restore Status fields that don't exist in v1beta1.
+	dst.Status.NodeInfo = restored.Status.NodeInfo
+
 	return nil
 }
 

api/v1beta1/conversion.go

@@ -108,3 +108,8 @@ func Convert_v1beta2_AWSMachineStatus_To_v1beta1_AWSMachineStatus(in *v1beta2.AW
 	// Note: DedicatedHostID is not present in v1beta1, so it will be dropped during conversion
 	return autoConvert_v1beta2_AWSMachineStatus_To_v1beta1_AWSMachineStatus(in, out, s)
 }
+
+func Convert_v1beta2_AWSMachineTemplateStatus_To_v1beta1_AWSMachineTemplateStatus(in *v1beta2.AWSMachineTemplateStatus, out *AWSMachineTemplateStatus, s conversion.Scope) error {
+	// NodeInfo field is ignored (dropped) as it doesn't exist in v1beta1
+	return autoConvert_v1beta2_AWSMachineTemplateStatus_To_v1beta1_AWSMachineTemplateStatus(in, out, s)
+}

api/v1beta1/zz_generated.conversion.go

@@ -23,13 +23,55 @@ import (
 	clusterv1 "sigs.k8s.io/cluster-api/api/v1beta1"
 )
 
+// Architecture represents the CPU architecture of the node.
+// Its underlying type is a string and its value can be any of amd64, arm64.
+type Architecture string
+
+// Architecture constants.
+const (
+	ArchitectureAmd64 Architecture = "amd64"
+	ArchitectureArm64 Architecture = "arm64"
+)
+
+// OperatingSystem represents the operating system of the node.
+// Its underlying type is a string and its value can be any of linux, windows.
+type OperatingSystem string
+
+// Operating system constants.
+const (
+	// OperatingSystemLinux represents the Linux operating system.
+	OperatingSystemLinux OperatingSystem = "linux"
+	// OperatingSystemWindows represents the Windows operating system.
+	OperatingSystemWindows OperatingSystem = "windows"
+)
+
+// NodeInfo contains information about the node's architecture and operating system.
+type NodeInfo struct {
+	// Architecture is the CPU architecture of the node.
+	// Its underlying type is a string and its value can be any of amd64, arm64.
+	// +kubebuilder:validation:Enum=amd64;arm64
+	// +optional
+	Architecture Architecture `json:"architecture,omitempty"`
+	// OperatingSystem is the operating system of the node.
+	// Its underlying type is a string and its value can be any of linux, windows.
+	// +kubebuilder:validation:Enum=linux;windows
+	// +optional
+	OperatingSystem OperatingSystem `json:"operatingSystem,omitempty"`
+}
+
 // AWSMachineTemplateStatus defines a status for an AWSMachineTemplate.
 type AWSMachineTemplateStatus struct {
 	// Capacity defines the resource capacity for this machine.
 	// This value is used for autoscaling from zero operations as defined in:
 	// https://github.com/kubernetes-sigs/cluster-api/blob/main/docs/proposals/20210310-opt-in-autoscaling-from-zero.md
 	// +optional
 	Capacity corev1.ResourceList `json:"capacity,omitempty"`
+
+	// NodeInfo contains information about the node's architecture and operating system.
+	// This value is used for autoscaling from zero operations as defined in:
+	// https://github.com/kubernetes-sigs/cluster-api/blob/main/docs/proposals/20210310-opt-in-autoscaling-from-zero.md
+	// +optional
+	NodeInfo *NodeInfo `json:"nodeInfo,omitempty"`
 }
 
 // AWSMachineTemplateSpec defines the desired state of AWSMachineTemplate.
@@ -40,6 +82,7 @@ type AWSMachineTemplateSpec struct {
 // +kubebuilder:object:root=true
 // +kubebuilder:resource:path=awsmachinetemplates,scope=Namespaced,categories=cluster-api,shortName=awsmt
 // +kubebuilder:storageversion
+// +kubebuilder:subresource:status
 // +k8s:defaulter-gen=true
 
 // AWSMachineTemplate is the schema for the Amazon EC2 Machine Templates API.

api/v1beta2/awsmachinetemplate_types.go

@@ -1156,7 +1156,32 @@ spec:
                   This value is used for autoscaling from zero operations as defined in:
                   https://github.com/kubernetes-sigs/cluster-api/blob/main/docs/proposals/20210310-opt-in-autoscaling-from-zero.md
                 type: object
+              nodeInfo:
+                description: |-
+                  NodeInfo contains information about the node's architecture and operating system.
+                  This value is used for autoscaling from zero operations as defined in:
+                  https://github.com/kubernetes-sigs/cluster-api/blob/main/docs/proposals/20210310-opt-in-autoscaling-from-zero.md
+                properties:
+                  architecture:
+                    description: |-
+                      Architecture is the CPU architecture of the node.
+                      Its underlying type is a string and its value can be any of amd64, arm64.
+                    enum:
+                    - amd64
+                    - arm64
+                    type: string
+                  operatingSystem:
+                    description: |-
+                      OperatingSystem is the operating system of the node.
+                      Its underlying type is a string and its value can be any of linux, windows.
+                    enum:
+                    - linux
+                    - windows
+                    type: string
+                type: object
             type: object
         type: object
     served: true
     storage: true
+    subresources:
+      status: {}

api/v1beta2/zz_generated.deepcopy.go

@@ -175,6 +175,7 @@ rules:
   resources:
   - awsclusters/status
   - awsfargateprofiles/status
+  - awsmachinetemplates/status
   - rosaclusters/status
   - rosanetworks/status
   - rosaroleconfigs/status