e2e_node: provide methods to update kubelet config via file

Signed-off-by: Artyom Lukianov <alukiano@redhat.com>

test/e2e_node/kubeletconfig/kubeletconfig.go

@@ -0,0 +1,95 @@
+/*
+Copyright 2021 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 kubeletconfig
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	kubeletconfigv1beta1 "k8s.io/kubelet/config/v1beta1"
+	kubeletconfig "k8s.io/kubernetes/pkg/kubelet/apis/config"
+	kubeletconfigscheme "k8s.io/kubernetes/pkg/kubelet/apis/config/scheme"
+	kubeletconfigcodec "k8s.io/kubernetes/pkg/kubelet/kubeletconfig/util/codec"
+
+	"sigs.k8s.io/yaml"
+)
+
+func getKubeletConfigFilePath() (string, error) {
+	cwd, err := os.Getwd()
+	if err != nil {
+		return "", fmt.Errorf("failed to get current working directory: %w", err)
+	}
+
+	// DO NOT name this file "kubelet" - you will overwrite the kubelet binary and be very confused :)
+	return filepath.Join(cwd, "kubelet-config"), nil
+}
+
+// GetCurrentKubeletConfigFromFile returns the current kubelet configuration under the filesystem.
+// This method should only run together with e2e node tests, meaning the test executor and the cluster nodes is the
+// same machine
+func GetCurrentKubeletConfigFromFile() (*kubeletconfig.KubeletConfiguration, error) {
+	kubeletConfigFilePath, err := getKubeletConfigFilePath()
+	if err != nil {
+		return nil, err
+	}
+
+	data, err := ioutil.ReadFile(kubeletConfigFilePath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get the kubelet config from the file %q: %w", kubeletConfigFilePath, err)
+	}
+
+	var kubeletConfigV1Beta1 kubeletconfigv1beta1.KubeletConfiguration
+	if err := yaml.Unmarshal(data, &kubeletConfigV1Beta1); err != nil {
+		return nil, fmt.Errorf("failed to unmarshal the kubelet config: %w", err)
+	}
+
+	scheme, _, err := kubeletconfigscheme.NewSchemeAndCodecs()
+	if err != nil {
+		return nil, err
+	}
+
+	kubeletConfig := kubeletconfig.KubeletConfiguration{}
+	err = scheme.Convert(&kubeletConfigV1Beta1, &kubeletConfig, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	return &kubeletConfig, nil
+}
+
+// WriteKubeletConfigFile updates the kubelet configuration under the filesystem
+// This method should only run together with e2e node tests, meaning the test executor and the cluster nodes is the
+// same machine
+func WriteKubeletConfigFile(kubeletConfig *kubeletconfig.KubeletConfiguration) error {
+	data, err := kubeletconfigcodec.EncodeKubeletConfig(kubeletConfig, kubeletconfigv1beta1.SchemeGroupVersion)
+	if err != nil {
+		return err
+	}
+
+	kubeletConfigFilePath, err := getKubeletConfigFilePath()
+	if err != nil {
+		return err
+	}
+
+	if err := ioutil.WriteFile(kubeletConfigFilePath, data, 0644); err != nil {
+		return fmt.Errorf("failed to write the kubelet file to %q: %w", kubeletConfigFilePath, err)
+	}
+
+	return nil
+}