issue 8960: implement PodVolume exposer for PVB/PVR

Signed-off-by: Lyndon-Li <lyonghui@vmware.com>

pkg/nodeagent/node_agent.go

@@ -41,6 +41,12 @@ const (
 
 	// nodeAgentRole marks pods with node-agent role on all nodes.
 	nodeAgentRole = "node-agent"
+
+	// hostPodVolume is the name of the volume in node-agent for host-pod mount
+	hostPodVolume = "host-pods"
+
+	// HostPodVolumeMountPoint is the mount point of the volume in node-agent for host-pod mount
+	HostPodVolumeMountPoint = "host_pods"
 )
 
 var (
@@ -249,3 +255,37 @@ func GetAnnotationValue(ctx context.Context, kubeClient kubernetes.Interface, na
 
 	return val, nil
 }
+
+func GetHostPodPath(ctx context.Context, kubeClient kubernetes.Interface, namespace string, osType string) (string, error) {
+	dsName := daemonSet
+	if osType == kube.NodeOSWindows {
+		dsName = daemonsetWindows
+	}
+
+	ds, err := kubeClient.AppsV1().DaemonSets(namespace).Get(ctx, dsName, metav1.GetOptions{})
+	if err != nil {
+		return "", errors.Wrapf(err, "error getting daemonset %s", dsName)
+	}
+
+	var volume *corev1api.Volume
+	for _, v := range ds.Spec.Template.Spec.Volumes {
+		if v.Name == hostPodVolume {
+			volume = &v
+			break
+		}
+	}
+
+	if volume == nil {
+		return "", errors.New("host pod volume is not found")
+	}
+
+	if volume.HostPath == nil {
+		return "", errors.New("host pod volume is not a host path volume")
+	}
+
+	if volume.HostPath.Path == "" {
+		return "", errors.New("host pod volume path is empty")
+	}
+
+	return volume.HostPath.Path, nil
+}

pkg/nodeagent/node_agent_test.go

@@ -590,3 +590,164 @@ func TestGetAnnotationValue(t *testing.T) {
 		})
 	}
 }
+
+func TestGetHostPodPath(t *testing.T) {
+	daemonSet := &appsv1api.DaemonSet{
+		ObjectMeta: metav1.ObjectMeta{
+			Namespace: "fake-ns",
+			Name:      "node-agent",
+		},
+		TypeMeta: metav1.TypeMeta{
+			Kind: "DaemonSet",
+		},
+	}
+
+	daemonSetWithHostPodVolume := &appsv1api.DaemonSet{
+		ObjectMeta: metav1.ObjectMeta{
+			Namespace: "fake-ns",
+			Name:      "node-agent",
+		},
+		TypeMeta: metav1.TypeMeta{
+			Kind: "DaemonSet",
+		},
+		Spec: appsv1api.DaemonSetSpec{
+			Template: corev1api.PodTemplateSpec{
+				Spec: corev1api.PodSpec{
+					Volumes: []corev1api.Volume{
+						{
+							Name: hostPodVolume,
+						},
+					},
+				},
+			},
+		},
+	}
+
+	daemonSetWithHostPodVolumeAndEmptyPath := &appsv1api.DaemonSet{
+		ObjectMeta: metav1.ObjectMeta{
+			Namespace: "fake-ns",
+			Name:      "node-agent",
+		},
+		TypeMeta: metav1.TypeMeta{
+			Kind: "DaemonSet",
+		},
+		Spec: appsv1api.DaemonSetSpec{
+			Template: corev1api.PodTemplateSpec{
+				Spec: corev1api.PodSpec{
+					Volumes: []corev1api.Volume{
+						{
+							Name: hostPodVolume,
+							VolumeSource: corev1api.VolumeSource{
+								HostPath: &corev1api.HostPathVolumeSource{},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	daemonSetWithHostPodVolumeAndValidPath := &appsv1api.DaemonSet{
+		ObjectMeta: metav1.ObjectMeta{
+			Namespace: "fake-ns",
+			Name:      "node-agent",
+		},
+		TypeMeta: metav1.TypeMeta{
+			Kind: "DaemonSet",
+		},
+		Spec: appsv1api.DaemonSetSpec{
+			Template: corev1api.PodTemplateSpec{
+				Spec: corev1api.PodSpec{
+					Volumes: []corev1api.Volume{
+						{
+							Name: hostPodVolume,
+							VolumeSource: corev1api.VolumeSource{
+								HostPath: &corev1api.HostPathVolumeSource{
+									Path: "/var/lib/kubelet/pods",
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	tests := []struct {
+		name          string
+		kubeClientObj []runtime.Object
+		namespace     string
+		osType        string
+		expectedValue string
+		expectErr     string
+	}{
+		{
+			name:      "ds get error",
+			namespace: "fake-ns",
+			osType:    kube.NodeOSWindows,
+			kubeClientObj: []runtime.Object{
+				daemonSet,
+			},
+			expectErr: "error getting daemonset node-agent-windows: daemonsets.apps \"node-agent-windows\" not found",
+		},
+		{
+			name:      "no host pod volume",
+			namespace: "fake-ns",
+			osType:    kube.NodeOSLinux,
+			kubeClientObj: []runtime.Object{
+				daemonSet,
+			},
+			expectErr: "host pod volume is not found",
+		},
+		{
+			name:      "no host pod volume path",
+			namespace: "fake-ns",
+			osType:    kube.NodeOSLinux,
+			kubeClientObj: []runtime.Object{
+				daemonSetWithHostPodVolume,
+			},
+			expectErr: "host pod volume is not a host path volume",
+		},
+		{
+			name:      "empty host pod volume path",
+			namespace: "fake-ns",
+			osType:    kube.NodeOSLinux,
+			kubeClientObj: []runtime.Object{
+				daemonSetWithHostPodVolumeAndEmptyPath,
+			},
+			expectErr: "host pod volume path is empty",
+		},
+		{
+			name:      "succeed",
+			namespace: "fake-ns",
+			osType:    kube.NodeOSLinux,
+			kubeClientObj: []runtime.Object{
+				daemonSetWithHostPodVolumeAndValidPath,
+			},
+			expectedValue: "/var/lib/kubelet/pods",
+		},
+		{
+			name:      "succeed on empty os type",
+			namespace: "fake-ns",
+			kubeClientObj: []runtime.Object{
+				daemonSetWithHostPodVolumeAndValidPath,
+			},
+			expectedValue: "/var/lib/kubelet/pods",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			fakeKubeClient := fake.NewSimpleClientset(test.kubeClientObj...)
+
+			path, err := GetHostPodPath(context.TODO(), fakeKubeClient, test.namespace, test.osType)
+
+			if test.expectErr == "" {
+				assert.NoError(t, err)
+				assert.Equal(t, test.expectedValue, path)
+			} else {
+				assert.EqualError(t, err, test.expectErr)
+			}
+		})
+	}
+}