add kubelet client for Pod resource info

This change introduces kubelet client to get allocated device
information of a Pod from newly added Kubelet grpc service.
For more information please see:
[kubernetes/kubernetes#70508](https://github.com/kubernetes/kubernetes/pull/70508)

Change-Id: I11e58ccdd52662601f445fa24c7d55c225441efc
Signed-off-by: Abdul Halim <abdul.halim@intel.com>
(cherry picked from commit d3c92b4aa2)

kubeletclient/kubeletclient_test.go

@@ -0,0 +1,209 @@
+package kubeletclient
+
+import (
+	"context"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+	"google.golang.org/grpc"
+	v1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	k8sTypes "k8s.io/apimachinery/pkg/types"
+	"k8s.io/kubernetes/pkg/kubelet/util"
+
+	mtypes "github.com/intel/multus-cni/types"
+	podresourcesapi "k8s.io/kubernetes/pkg/kubelet/apis/podresources/v1alpha1"
+)
+
+var (
+	socketDir  string
+	socketName string
+	fakeServer *fakeResourceServer
+)
+
+type fakeResourceServer struct {
+	server *grpc.Server
+}
+
+func (m *fakeResourceServer) List(ctx context.Context, req *podresourcesapi.ListPodResourcesRequest) (*podresourcesapi.ListPodResourcesResponse, error) {
+	podName := "pod-name"
+	podNamespace := "pod-namespace"
+	containerName := "container-name"
+
+	devs := []*podresourcesapi.ContainerDevices{
+		{
+			ResourceName: "resource",
+			DeviceIds:    []string{"dev0", "dev1"},
+		},
+	}
+
+	resp := &podresourcesapi.ListPodResourcesResponse{
+		PodResources: []*podresourcesapi.PodResources{
+			{
+				Name:      podName,
+				Namespace: podNamespace,
+				Containers: []*podresourcesapi.ContainerResources{
+					{
+						Name:    containerName,
+						Devices: devs,
+					},
+				},
+			},
+		},
+	}
+	return resp, nil
+}
+
+func TestKubeletclient(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Kubeletclient Suite")
+}
+
+func setUp() error {
+	tempSocketDir, err := ioutil.TempDir("", "kubelet-resource-client")
+	if err != nil {
+		return err
+	}
+	defaultPodResourcesPath = filepath.Join(tempSocketDir, defaultPodResourcesPath)
+
+	if err := os.MkdirAll(defaultPodResourcesPath, os.ModeDir); err != nil {
+		return err
+	}
+
+	socketDir = defaultPodResourcesPath
+	socketName = filepath.Join(socketDir, "kubelet.sock")
+
+	fakeServer = &fakeResourceServer{server: grpc.NewServer()}
+	podresourcesapi.RegisterPodResourcesListerServer(fakeServer.server, fakeServer)
+	lis, err := util.CreateListener(socketName)
+	if err != nil {
+		return nil
+	}
+	go fakeServer.server.Serve(lis)
+	return nil
+}
+
+func tearDown(path string) error {
+	if fakeServer != nil {
+		fakeServer.server.Stop()
+	}
+	if err := os.RemoveAll(path); err != nil {
+		return err
+	}
+	return nil
+}
+
+var _ = BeforeSuite(func() {
+	err := setUp()
+	Expect(err).NotTo(HaveOccurred())
+})
+
+var _ = AfterSuite(func() {
+	err := tearDown(socketDir)
+	Expect(err).NotTo(HaveOccurred())
+})
+
+var _ = Describe("Kubelet resource endpoint data read operations", func() {
+
+	Context("GetResourceClient()", func() {
+		It("should return no error", func() {
+			kubeletSocket = socketName
+			_, err := GetResourceClient()
+			Expect(err).NotTo(HaveOccurred())
+		})
+	})
+
+	Context("GetPodResourceMap() with valid pod name and namespace", func() {
+		It("should return no error", func() {
+			podUID := k8sTypes.UID("970a395d-bb3b-11e8-89df-408d5c537d23")
+			fakePod := &v1.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "pod-name",
+					Namespace: "pod-namespace",
+					UID:       podUID,
+				},
+				Spec: v1.PodSpec{
+					Containers: []v1.Container{
+						{
+							Name: "container-name",
+						},
+					},
+				},
+			}
+			kubeletSocket = socketName
+			client, err := getKubeletClient()
+			Expect(err).NotTo(HaveOccurred())
+
+			outputRMap := map[string]*mtypes.ResourceInfo{
+				"resource": &mtypes.ResourceInfo{DeviceIDs: []string{"dev0", "dev1"}},
+			}
+			resourceMap, err := client.GetPodResourceMap(fakePod)
+			Expect(err).NotTo(HaveOccurred())
+			Expect(resourceMap).ShouldNot(BeNil())
+			Expect(resourceMap).To(Equal(outputRMap))
+		})
+	})
+
+	Context("GetPodResourceMap() with empty podname", func() {
+		It("should return error", func() {
+			podUID := k8sTypes.UID("970a395d-bb3b-11e8-89df-408d5c537d23")
+			fakePod := &v1.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "",
+					Namespace: "pod-namespace",
+					UID:       podUID,
+				},
+			}
+			kubeletSocket = socketName
+			client, err := getKubeletClient()
+			Expect(err).NotTo(HaveOccurred())
+			_, err = client.GetPodResourceMap(fakePod)
+			Expect(err).To(HaveOccurred())
+		})
+	})
+
+	Context("GetPodResourceMap() with empty namespace", func() {
+		It("should return error", func() {
+			podUID := k8sTypes.UID("970a395d-bb3b-11e8-89df-408d5c537d23")
+			fakePod := &v1.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "pod-name",
+					Namespace: "",
+					UID:       podUID,
+				},
+			}
+			kubeletSocket = socketName
+			client, err := getKubeletClient()
+			Expect(err).NotTo(HaveOccurred())
+			_, err = client.GetPodResourceMap(fakePod)
+			Expect(err).To(HaveOccurred())
+		})
+	})
+
+	Context("GetPodResourceMap() with non-existent podname and namespace", func() {
+		It("should return no error", func() {
+			podUID := k8sTypes.UID("970a395d-bb3b-11e8-89df-408d5c537d23")
+			fakePod := &v1.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "whateverpod",
+					Namespace: "whatevernamespace",
+					UID:       podUID,
+				},
+			}
+
+			kubeletSocket = socketName
+			client, err := getKubeletClient()
+			Expect(err).NotTo(HaveOccurred())
+
+			emptyRMap := map[string]*mtypes.ResourceInfo{}
+			resourceMap, err := client.GetPodResourceMap(fakePod)
+			Expect(err).NotTo(HaveOccurred())
+			Expect(resourceMap).ShouldNot(BeNil())
+			Expect(resourceMap).To(Equal(emptyRMap))
+		})
+	})
+})