check existence of the same label from node-agent

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

pkg/nodeagent/node_agent.go

@@ -38,7 +38,8 @@ const (
 )
 
 var (
-	ErrDaemonSetNotFound = errors.New("daemonset not found")
+	ErrDaemonSetNotFound      = errors.New("daemonset not found")
+	ErrNodeAgentLabelNotFound = errors.New("node-agent label not found")
 )
 
 type LoadConcurrency struct {
@@ -161,3 +162,21 @@ func GetConfigs(ctx context.Context, namespace string, kubeClient kubernetes.Int
 
 	return configs, nil
 }
+
+func GetLabelValue(ctx context.Context, kubeClient kubernetes.Interface, namespace string, key string) (string, error) {
+	ds, err := kubeClient.AppsV1().DaemonSets(namespace).Get(ctx, daemonSet, metav1.GetOptions{})
+	if err != nil {
+		return "", errors.Wrap(err, "error getting node-agent daemonset")
+	}
+
+	if ds.Spec.Template.Labels == nil {
+		return "", ErrNodeAgentLabelNotFound
+	}
+
+	val, found := ds.Spec.Template.Labels[key]
+	if !found {
+		return "", ErrNodeAgentLabelNotFound
+	}
+
+	return val, nil
+}

pkg/nodeagent/node_agent_test.go

@@ -331,3 +331,132 @@ func TestGetConfigs(t *testing.T) {
 		})
 	}
 }
+
+func TestGetLabelValue(t *testing.T) {
+	daemonSet := &appsv1.DaemonSet{
+		ObjectMeta: metav1.ObjectMeta{
+			Namespace: "fake-ns",
+			Name:      "node-agent",
+		},
+		TypeMeta: metav1.TypeMeta{
+			Kind: "DaemonSet",
+		},
+	}
+
+	daemonSetWithOtherLabel := &appsv1.DaemonSet{
+		ObjectMeta: metav1.ObjectMeta{
+			Namespace: "fake-ns",
+			Name:      "node-agent",
+		},
+		TypeMeta: metav1.TypeMeta{
+			Kind: "DaemonSet",
+		},
+		Spec: appsv1.DaemonSetSpec{
+			Template: corev1.PodTemplateSpec{
+				ObjectMeta: metav1.ObjectMeta{
+					Labels: map[string]string{
+						"fake-other-label": "fake-value-1",
+					},
+				},
+			},
+		},
+	}
+
+	daemonSetWithLabel := &appsv1.DaemonSet{
+		ObjectMeta: metav1.ObjectMeta{
+			Namespace: "fake-ns",
+			Name:      "node-agent",
+		},
+		TypeMeta: metav1.TypeMeta{
+			Kind: "DaemonSet",
+		},
+		Spec: appsv1.DaemonSetSpec{
+			Template: corev1.PodTemplateSpec{
+				ObjectMeta: metav1.ObjectMeta{
+					Labels: map[string]string{
+						"fake-label": "fake-value-2",
+					},
+				},
+			},
+		},
+	}
+
+	daemonSetWithEmptyLabel := &appsv1.DaemonSet{
+		ObjectMeta: metav1.ObjectMeta{
+			Namespace: "fake-ns",
+			Name:      "node-agent",
+		},
+		TypeMeta: metav1.TypeMeta{
+			Kind: "DaemonSet",
+		},
+		Spec: appsv1.DaemonSetSpec{
+			Template: corev1.PodTemplateSpec{
+				ObjectMeta: metav1.ObjectMeta{
+					Labels: map[string]string{
+						"fake-label": "",
+					},
+				},
+			},
+		},
+	}
+
+	tests := []struct {
+		name          string
+		kubeClientObj []runtime.Object
+		namespace     string
+		expectedValue string
+		expectErr     string
+	}{
+		{
+			name:      "ds get error",
+			namespace: "fake-ns",
+			expectErr: "error getting node-agent daemonset: daemonsets.apps \"node-agent\" not found",
+		},
+		{
+			name:      "no label",
+			namespace: "fake-ns",
+			kubeClientObj: []runtime.Object{
+				daemonSet,
+			},
+			expectErr: ErrNodeAgentLabelNotFound.Error(),
+		},
+		{
+			name:      "no expecting label",
+			namespace: "fake-ns",
+			kubeClientObj: []runtime.Object{
+				daemonSetWithOtherLabel,
+			},
+			expectErr: ErrNodeAgentLabelNotFound.Error(),
+		},
+		{
+			name:      "expecting label",
+			namespace: "fake-ns",
+			kubeClientObj: []runtime.Object{
+				daemonSetWithLabel,
+			},
+			expectedValue: "fake-value-2",
+		},
+		{
+			name:      "expecting empty label",
+			namespace: "fake-ns",
+			kubeClientObj: []runtime.Object{
+				daemonSetWithEmptyLabel,
+			},
+			expectedValue: "",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			fakeKubeClient := fake.NewSimpleClientset(test.kubeClientObj...)
+
+			value, err := GetLabelValue(context.TODO(), fakeKubeClient, test.namespace, "fake-label")
+			if test.expectErr == "" {
+				assert.NoError(t, err)
+				assert.Equal(t, test.expectedValue, value)
+			} else {
+				assert.EqualError(t, err, test.expectErr)
+			}
+		})
+	}
+}