pkg/proxy: move get kernel version out of ipvs proxier

Signed-off-by: Daman Arora <aroradaman@gmail.com>

pkg/util/kernel/version.go

@@ -0,0 +1,48 @@
+/*
+Copyright 2023 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 kernel
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"k8s.io/apimachinery/pkg/util/version"
+)
+
+type readFileFunc func(string) ([]byte, error)
+
+// GetVersion returns currently running kernel version.
+func GetVersion() (*version.Version, error) {
+	return getVersion(os.ReadFile)
+}
+
+// getVersion reads os release file from the give readFile function.
+func getVersion(readFile readFileFunc) (*version.Version, error) {
+	kernelVersionFile := "/proc/sys/kernel/osrelease"
+	fileContent, err := readFile(kernelVersionFile)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read os-release file: %s", err.Error())
+	}
+
+	kernelVersion, err := version.ParseGeneric(strings.TrimSpace(string(fileContent)))
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse kernel version: %s", err.Error())
+	}
+
+	return kernelVersion, nil
+}