add flag `--no-headers` to `kubectl top ...`

pkg/kubectl/cmd/top_node.go

@@ -40,6 +40,7 @@ import (
 type TopNodeOptions struct {
 	ResourceName    string
 	Selector        string
+	NoHeaders       bool
 	NodeClient      corev1client.CoreV1Interface
 	HeapsterOptions HeapsterTopOptions
 	Client          *metricsutil.HeapsterMetricsClient
@@ -118,6 +119,8 @@ func NewCmdTopNode(f cmdutil.Factory, o *TopNodeOptions, streams genericclioptio
 		Aliases: []string{"nodes", "no"},
 	}
 	cmd.Flags().StringVarP(&o.Selector, "selector", "l", o.Selector, "Selector (label query) to filter on, supports '=', '==', and '!='.(e.g. -l key1=value1,key2=value2)")
+	cmd.Flags().BoolVar(&o.NoHeaders, "no-headers", o.NoHeaders, "If present, print output without headers")
+
 	o.HeapsterOptions.Bind(cmd.Flags())
 	return cmd
 }
@@ -216,7 +219,7 @@ func (o TopNodeOptions) RunTopNode() error {
 		allocatable[n.Name] = n.Status.Allocatable
 	}
 
-	return o.Printer.PrintNodeMetrics(metrics.Items, allocatable)
+	return o.Printer.PrintNodeMetrics(metrics.Items, allocatable, o.NoHeaders)
 }
 
 func getNodeMetricsFromMetricsAPI(metricsClient metricsclientset.Interface, resourceName string, selector labels.Selector) (*metricsapi.NodeMetricsList, error) {

pkg/kubectl/cmd/top_node_test.go

@@ -81,6 +81,7 @@ func TestTopNodeAllMetrics(t *testing.T) {
 	streams, _, buf, _ := genericclioptions.NewTestIOStreams()
 
 	cmd := NewCmdTopNode(tf, nil, streams)
+	cmd.Flags().Set("no-headers", "true")
 	cmd.Run(cmd, []string{})
 
 	// Check the presence of node names in the output.
@@ -90,6 +91,9 @@ func TestTopNodeAllMetrics(t *testing.T) {
 			t.Errorf("missing metrics for %s: \n%s", m.Name, result)
 		}
 	}
+	if strings.Contains(result, "MEMORY") {
+		t.Errorf("should not print headers with --no-headers option set:\n%s\n", result)
+	}
 }
 
 func TestTopNodeAllMetricsCustomDefaults(t *testing.T) {

pkg/kubectl/cmd/top_pod.go

@@ -45,6 +45,7 @@ type TopPodOptions struct {
 	Selector        string
 	AllNamespaces   bool
 	PrintContainers bool
+	NoHeaders       bool
 	PodClient       corev1client.PodsGetter
 	HeapsterOptions HeapsterTopOptions
 	Client          *metricsutil.HeapsterMetricsClient
@@ -109,6 +110,7 @@ func NewCmdTopPod(f cmdutil.Factory, o *TopPodOptions, streams genericclioptions
 	cmd.Flags().StringVarP(&o.Selector, "selector", "l", o.Selector, "Selector (label query) to filter on, supports '=', '==', and '!='.(e.g. -l key1=value1,key2=value2)")
 	cmd.Flags().BoolVar(&o.PrintContainers, "containers", o.PrintContainers, "If present, print usage of containers within a pod.")
 	cmd.Flags().BoolVar(&o.AllNamespaces, "all-namespaces", o.AllNamespaces, "If present, list the requested object(s) across all namespaces. Namespace in current context is ignored even if specified with --namespace.")
+	cmd.Flags().BoolVar(&o.NoHeaders, "no-headers", o.NoHeaders, "If present, print output without headers.")
 	o.HeapsterOptions.Bind(cmd.Flags())
 	return cmd
 }
@@ -198,7 +200,7 @@ func (o TopPodOptions) RunTopPod() error {
 		return err
 	}
 
-	return o.Printer.PrintPodMetrics(metrics.Items, o.PrintContainers, o.AllNamespaces)
+	return o.Printer.PrintPodMetrics(metrics.Items, o.PrintContainers, o.AllNamespaces, o.NoHeaders)
 }
 
 func getMetricsFromMetricsAPI(metricsClient metricsclientset.Interface, namespace, resourceName string, allNamespaces bool, selector labels.Selector) (*metricsapi.PodMetricsList, error) {

pkg/kubectl/cmd/top_pod_test.go

@@ -37,6 +37,7 @@ import (
 	"k8s.io/client-go/rest/fake"
 	core "k8s.io/client-go/testing"
 	cmdtesting "k8s.io/kubernetes/pkg/kubectl/cmd/testing"
+	cmdutil "k8s.io/kubernetes/pkg/kubectl/cmd/util"
 	"k8s.io/kubernetes/pkg/kubectl/scheme"
 	metricsv1alpha1api "k8s.io/metrics/pkg/apis/metrics/v1alpha1"
 	metricsv1beta1api "k8s.io/metrics/pkg/apis/metrics/v1beta1"
@@ -132,6 +133,14 @@ func TestTopPod(t *testing.T) {
 			namespaces:   []string{testNS},
 			containers:   true,
 		},
+		{
+			name:         "no-headers set",
+			flags:        map[string]string{"containers": "true", "no-headers": "true"},
+			args:         []string{"pod1"},
+			expectedPath: topPathPrefix + "/namespaces/" + testNS + "/pods/pod1",
+			namespaces:   []string{testNS},
+			containers:   true,
+		},
 	}
 	initTestErrorHandler(t)
 	for _, testCase := range testCases {
@@ -221,6 +230,9 @@ func TestTopPod(t *testing.T) {
 					t.Errorf("%s: unexpected metrics for %s: \n%s", testCase.name, name, result)
 				}
 			}
+			if cmdutil.GetFlagBool(cmd, "no-headers") && strings.Contains(result, "MEMORY") {
+				t.Errorf("%s: unexpected headers with no-headers option set: \n%s", testCase.name, result)
+			}
 		})
 	}
 }

pkg/kubectl/metricsutil/metrics_printer.go

@@ -53,7 +53,7 @@ func NewTopCmdPrinter(out io.Writer) *TopCmdPrinter {
 	return &TopCmdPrinter{out: out}
 }
 
-func (printer *TopCmdPrinter) PrintNodeMetrics(metrics []metricsapi.NodeMetrics, availableResources map[string]v1.ResourceList) error {
+func (printer *TopCmdPrinter) PrintNodeMetrics(metrics []metricsapi.NodeMetrics, availableResources map[string]v1.ResourceList, noHeaders bool) error {
 	if len(metrics) == 0 {
 		return nil
 	}
@@ -63,8 +63,9 @@ func (printer *TopCmdPrinter) PrintNodeMetrics(metrics []metricsapi.NodeMetrics,
 	sort.Slice(metrics, func(i, j int) bool {
 		return metrics[i].Name < metrics[j].Name
 	})
-
-	printColumnNames(w, NodeColumns)
+	if !noHeaders {
+		printColumnNames(w, NodeColumns)
+	}
 	var usage v1.ResourceList
 	for _, m := range metrics {
 		err := scheme.Scheme.Convert(&m.Usage, &usage, nil)
@@ -86,18 +87,20 @@ func (printer *TopCmdPrinter) PrintNodeMetrics(metrics []metricsapi.NodeMetrics,
 	return nil
 }
 
-func (printer *TopCmdPrinter) PrintPodMetrics(metrics []metricsapi.PodMetrics, printContainers bool, withNamespace bool) error {
+func (printer *TopCmdPrinter) PrintPodMetrics(metrics []metricsapi.PodMetrics, printContainers bool, withNamespace bool, noHeaders bool) error {
 	if len(metrics) == 0 {
 		return nil
 	}
 	w := printers.GetNewTabWriter(printer.out)
 	defer w.Flush()
-
-	if withNamespace {
-		printValue(w, NamespaceColumn)
-	}
-	if printContainers {
-		printValue(w, PodColumn)
+	if !noHeaders {
+		if withNamespace {
+			printValue(w, NamespaceColumn)
+		}
+		if printContainers {
+			printValue(w, PodColumn)
+		}
+		printColumnNames(w, PodColumns)
 	}
 
 	sort.Slice(metrics, func(i, j int) bool {
@@ -106,8 +109,6 @@ func (printer *TopCmdPrinter) PrintPodMetrics(metrics []metricsapi.PodMetrics, p
 		}
 		return metrics[i].Name < metrics[j].Name
 	})
-
-	printColumnNames(w, PodColumns)
 	for _, m := range metrics {
 		err := printSinglePodMetrics(w, &m, printContainers, withNamespace)
 		if err != nil {