refact(csi): use common lib-csi imports (#263)

Signed-off-by: shubham <shubham.bajpai@mayadata.io>

vendor/github.com/openebs/lib-csi/pkg/client/k8s/namespace.go

@@ -0,0 +1,59 @@
+/*
+Copyright 2020 The OpenEBS 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 k8s
+
+import (
+	"github.com/pkg/errors"
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+// NamespaceGetter abstracts fetching of Namespace from kubernetes cluster
+type NamespaceGetter interface {
+	Get(name string, options metav1.GetOptions) (*corev1.Namespace, error)
+}
+
+// NamespaceLister abstracts fetching of a list of namespaces from kubernetes cluster
+type NamespaceLister interface {
+	List(options metav1.ListOptions) (*corev1.NamespaceList, error)
+}
+
+// NamespaceStruct is used to initialise kubernetes namespace instnaces
+type NamespaceStruct struct{}
+
+// Namespace returns a pointer to the namespace struct
+func Namespace() *NamespaceStruct {
+	return &NamespaceStruct{}
+}
+
+// Get returns a namespace instance from kubernetes cluster
+func (ns *NamespaceStruct) Get(name string, options metav1.GetOptions) (*corev1.Namespace, error) {
+	cs, err := Clientset().Get()
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to get namespace: %s", name)
+	}
+	return cs.CoreV1().Namespaces().Get(name, options)
+}
+
+// List returns a slice of namespaces defined in a Kubernetes cluster
+func (ns *NamespaceStruct) List(options metav1.ListOptions) (*corev1.NamespaceList, error) {
+	cs, err := Clientset().Get()
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to get namespaces")
+	}
+	return cs.CoreV1().Namespaces().List(options)
+}