cleanup: move k8s functions to the util/k8s package

By placing the NewK8sClient() function in its own package, the KMS API
can be split from the "internal/util" package. Some of the KMS providers
use the NewK8sClient() function, and this causes circular dependencies
between "internal/utils" -> "internal/kms" -> "internal/utils", which
are not alowed in Go.

Updates: #852
Signed-off-by: Niels de Vos <ndevos@redhat.com>

internal/util/k8s/client.go

@@ -0,0 +1,51 @@
+/*
+Copyright 2020 The CephCSI 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/LICENSE2.0
+
+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 k8s
+
+import (
+	"os"
+
+	"github.com/ceph/ceph-csi/internal/util/log"
+
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
+)
+
+// NewK8sClient create kubernetes client.
+func NewK8sClient() *kubernetes.Clientset {
+	var cfg *rest.Config
+	var err error
+	cPath := os.Getenv("KUBERNETES_CONFIG_PATH")
+	if cPath != "" {
+		cfg, err = clientcmd.BuildConfigFromFlags("", cPath)
+		if err != nil {
+			log.FatalLogMsg("Failed to get cluster config with error: %v\n", err)
+		}
+	} else {
+		cfg, err = rest.InClusterConfig()
+		if err != nil {
+			log.FatalLogMsg("Failed to get cluster config with error: %v\n", err)
+		}
+	}
+	client, err := kubernetes.NewForConfig(cfg)
+	if err != nil {
+		log.FatalLogMsg("Failed to create client with error: %v\n", err)
+	}
+
+	return client
+}