Add software versions to "kubectl get nodes -o wide" output.

Added "OS-IMAGE" and "KERNEL-VERSION" two columns to
"kubectl get nodes -o wide" output. This will help to provide
more information for user to locate or debug issues. See discussion
in ticket kubernetes#25579

Author: xingzhou

pkg/kubectl/resource_printer.go

@@ -494,7 +494,7 @@ var (
 	statefulSetColumns               = []string{"NAME", "DESIRED", "CURRENT", "AGE"}
 	endpointColumns                  = []string{"NAME", "ENDPOINTS", "AGE"}
 	nodeColumns                      = []string{"NAME", "STATUS", "AGE", "VERSION"}
-	nodeWideColumns                  = []string{"EXTERNAL-IP"}
+	nodeWideColumns                  = []string{"EXTERNAL-IP", "OS-IMAGE", "KERNEL-VERSION"}
 	daemonSetColumns                 = []string{"NAME", "DESIRED", "CURRENT", "READY", "NODE-SELECTOR", "AGE"}
 	daemonSetWideColumns             = []string{"CONTAINER(S)", "IMAGE(S)", "SELECTOR"}
 	eventColumns                     = []string{"LASTSEEN", "FIRSTSEEN", "COUNT", "NAME", "KIND", "SUBOBJECT", "TYPE", "REASON", "SOURCE", "MESSAGE"}
@@ -1550,7 +1550,14 @@ func printNode(node *api.Node, w io.Writer, options PrintOptions) error {
 	}
 
 	if options.Wide {
-		if _, err := fmt.Fprintf(w, "\t%s", getNodeExternalIP(node)); err != nil {
+		osImage, kernelVersion := node.Status.NodeInfo.OSImage, node.Status.NodeInfo.KernelVersion
+		if osImage == "" {
+			osImage = "<unknown>"
+		}
+		if kernelVersion == "" {
+			kernelVersion = "<unknown>"
+		}
+		if _, err := fmt.Fprintf(w, "\t%s\t%s\t%s", getNodeExternalIP(node), osImage, kernelVersion); err != nil {
 			return err
 		}
 	}

pkg/kubectl/resource_printer_test.go

@@ -727,6 +727,94 @@ func TestPrintNodeStatus(t *testing.T) {
 	}
 }
 
+func TestPrintNodeOSImage(t *testing.T) {
+	printer := NewHumanReadablePrinter(PrintOptions{
+		ColumnLabels: []string{},
+		Wide:         true,
+	})
+
+	table := []struct {
+		node    api.Node
+		osImage string
+	}{
+		{
+			node: api.Node{
+				ObjectMeta: api.ObjectMeta{Name: "foo1"},
+				Status: api.NodeStatus{
+					NodeInfo:  api.NodeSystemInfo{OSImage: "fake-os-image"},
+					Addresses: []api.NodeAddress{{Type: api.NodeExternalIP, Address: "1.1.1.1"}},
+				},
+			},
+			osImage: "fake-os-image",
+		},
+		{
+			node: api.Node{
+				ObjectMeta: api.ObjectMeta{Name: "foo2"},
+				Status: api.NodeStatus{
+					NodeInfo:  api.NodeSystemInfo{KernelVersion: "fake-kernel-version"},
+					Addresses: []api.NodeAddress{{Type: api.NodeExternalIP, Address: "1.1.1.1"}},
+				},
+			},
+			osImage: "<unknown>",
+		},
+	}
+
+	for _, test := range table {
+		buffer := &bytes.Buffer{}
+		err := printer.PrintObj(&test.node, buffer)
+		if err != nil {
+			t.Fatalf("An error occurred printing Node: %#v", err)
+		}
+		if !contains(strings.Fields(buffer.String()), test.osImage) {
+			t.Fatalf("Expect printing node %s with os image %#v, got: %#v", test.node.Name, test.osImage, buffer.String())
+		}
+	}
+}
+
+func TestPrintNodeKernelVersion(t *testing.T) {
+	printer := NewHumanReadablePrinter(PrintOptions{
+		ColumnLabels: []string{},
+		Wide:         true,
+	})
+
+	table := []struct {
+		node          api.Node
+		kernelVersion string
+	}{
+		{
+			node: api.Node{
+				ObjectMeta: api.ObjectMeta{Name: "foo1"},
+				Status: api.NodeStatus{
+					NodeInfo:  api.NodeSystemInfo{KernelVersion: "fake-kernel-version"},
+					Addresses: []api.NodeAddress{{Type: api.NodeExternalIP, Address: "1.1.1.1"}},
+				},
+			},
+			kernelVersion: "fake-kernel-version",
+		},
+		{
+			node: api.Node{
+				ObjectMeta: api.ObjectMeta{Name: "foo2"},
+				Status: api.NodeStatus{
+					NodeInfo:  api.NodeSystemInfo{OSImage: "fake-os-image"},
+					Addresses: []api.NodeAddress{{Type: api.NodeExternalIP, Address: "1.1.1.1"}},
+				},
+			},
+			kernelVersion: "<unknown>",
+		},
+	}
+
+	for _, test := range table {
+		buffer := &bytes.Buffer{}
+		err := printer.PrintObj(&test.node, buffer)
+		if err != nil {
+			t.Fatalf("An error occurred printing Node: %#v", err)
+		}
+		if !contains(strings.Fields(buffer.String()), test.kernelVersion) {
+			t.Fatalf("Expect printing node %s with kernel version %#v, got: %#v", test.node.Name, test.kernelVersion, buffer.String())
+		}
+	}
+}
+
 func TestPrintNodeExternalIP(t *testing.T) {
 	printer := NewHumanReadablePrinter(PrintOptions{
 		Wide: true,