Windows: do not use 'uname' for doing OS validation

The idea of the OS validator is to check if the host OS is supported.
e.g. 'uname' would return 'Linux' on Linux and something else on
OSX, BSD.

But 'uname' is a Unix tool, and only available on Windows if third
party packages are installed like MSYS.

- Split the os_validator*.go files for Unix and Windows.
- Align the fetching of OS name and kernel version for Windows
with the kubelet which uses the CurrentVersion reg key under HKLM.
- In the Windows spec use 'Windows Server' as the required name
and match it in 'CurrentVersion.ProductName' as a prefix.
- Add OS specific unit tests.

validators/os_validator.go → validators/os_validator_unix.go

@@ -1,3 +1,6 @@
+//go:build !windows
+// +build !windows
+
 /*
 Copyright 2016 The Kubernetes Authors.
 
@@ -38,7 +41,7 @@ func (o *OSValidator) Name() string {
 func (o *OSValidator) Validate(spec SysSpec) ([]error, []error) {
 	os, err := exec.Command("uname").CombinedOutput()
 	if err != nil {
-		return nil, []error{fmt.Errorf("failed to get os name: %w", err)}
+		return nil, []error{fmt.Errorf("failed to get OS name: %w", err)}
 	}
 	if err = o.validateOS(strings.TrimSpace(string(os)), spec.OS); err != nil {
 		return nil, []error{err}

validators/os_validator_test.go → validators/os_validator_unix_test.go

@@ -1,3 +1,6 @@
+//go:build !windows
+// +build !windows
+
 /*
 Copyright 2016 The Kubernetes Authors.
 

validators/os_validator_windows.go

@@ -0,0 +1,62 @@
+//go:build windows
+// +build windows
+
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package system
+
+import (
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+var _ Validator = &OSValidator{}
+
+// OSValidator validates OS.
+type OSValidator struct {
+	Reporter Reporter
+}
+
+// Name is part of the system.Validator interface.
+func (o *OSValidator) Name() string {
+	return "os"
+}
+
+// Validate is part of the system.Validator interface.
+func (o *OSValidator) Validate(spec SysSpec) ([]error, []error) {
+	args := []string{`(Get-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion').ProductName`}
+	os, err := exec.Command("powershell", args...).Output()
+	if err != nil {
+		return nil, []error{fmt.Errorf("failed to get OS name: %w", err)}
+	}
+	if err = o.validateOS(strings.TrimSpace(string(os)), spec.OS); err != nil {
+		return nil, []error{err}
+	}
+	return nil, nil
+}
+
+// validateOS would check if the reported string such as 'Windows Server 2019' contains
+// the required OS prefix from the spec 'Windows Server'.
+func (o *OSValidator) validateOS(os, specOS string) error {
+	if !strings.HasPrefix(os, specOS) {
+		o.Reporter.Report("OS", os, bad)
+		return fmt.Errorf("unsupported operating system: %s", os)
+	}
+	o.Reporter.Report("OS", os, good)
+	return nil
+}

validators/os_validator_windows_test.go

@@ -0,0 +1,59 @@
+//go:build windows
+// +build windows
+
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package system
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestValidateOS(t *testing.T) {
+	v := &OSValidator{
+		Reporter: DefaultReporter,
+	}
+	specOS := "Windows Server"
+	for _, test := range []struct {
+		os  string
+		err bool
+	}{
+		{
+			os:  "Windows Server",
+			err: false,
+		},
+		{
+			os:  "Windows 10 Enterprise",
+			err: true,
+		},
+		{
+			os:  "Windows",
+			err: true,
+		},
+	} {
+		t.Run(test.os, func(t *testing.T) {
+			err := v.validateOS(test.os, specOS)
+			if !test.err {
+				assert.Nil(t, err, "Expect error not to occur with os %q", test.os)
+			} else {
+				assert.NotNil(t, err, "Expect error to occur with os %q", test.os)
+			}
+		})
+	}
+}

validators/types_windows.go

@@ -24,9 +24,9 @@ import (
 	"strings"
 )
 
-// DefaultSysSpec is the default SysSpec for Windows
+// DefaultSysSpec is the default SysSpec for Windows.
 var DefaultSysSpec = SysSpec{
-	OS: "Microsoft Windows Server 2016",
+	OS: "Windows Server",
 	KernelSpec: KernelSpec{
 		Versions:     []string{`10\.0\.1439[3-9]`, `10\.0\.14[4-9][0-9]{2}`, `10\.0\.1[5-9][0-9]{3}`, `10\.0\.[2-9][0-9]{4}`, `10\.[1-9]+\.[0-9]+`}, //requires >= '10.0.14393'
 		VersionsNote: "The kernel version should be >= '10.0.14393'",
@@ -47,9 +47,11 @@ type KernelValidatorHelperImpl struct{}
 
 var _ KernelValidatorHelper = &KernelValidatorHelperImpl{}
 
-// GetKernelReleaseVersion returns the windows release version (ex. 10.0.14393) as a string
+// GetKernelReleaseVersion returns the Windows release version (e.g. 10.0.14393) as a string.
+// It does not include the UBR (revision)
 func (o *KernelValidatorHelperImpl) GetKernelReleaseVersion() (string, error) {
-	args := []string{"(Get-CimInstance Win32_OperatingSystem).Version"}
+	args := []string{`$props = Get-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion'; ` +
+		`"$($props.CurrentMajorVersionNumber).$($props.CurrentMinorVersionNumber).$($props.CurrentBuildNumber)"`}
 	releaseVersion, err := exec.Command("powershell", args...).Output()
 	if err != nil {
 		return "", err