AWS: kubectl get service should print hostnames for LoadBalancer services

Fixes #21526

Also test wide outputs. We only guarantee the first IP to be fully printed
if multiple ingresses are present. For AWS, which has no ingress IPs, but
only hostnames, the ELB hostname will be truncated, unless -o=wide is
specified.

pkg/kubectl/describe.go

@@ -1294,7 +1294,7 @@ func (i *IngressDescriber) describeIngress(ing *extensions.Ingress, describerSet
 	return tabbedString(func(out io.Writer) error {
 		fmt.Fprintf(out, "Name:\t%v\n", ing.Name)
 		fmt.Fprintf(out, "Namespace:\t%v\n", ing.Namespace)
-		fmt.Fprintf(out, "Address:\t%v\n", loadBalancerStatusStringer(ing.Status.LoadBalancer))
+		fmt.Fprintf(out, "Address:\t%v\n", loadBalancerStatusStringer(ing.Status.LoadBalancer, true))
 		def := ing.Spec.Backend
 		ns := ing.Namespace
 		if def == nil {

pkg/kubectl/resource_printer.go

@@ -53,6 +53,7 @@ const (
 	tabwriterPadding  = 3
 	tabwriterPadChar  = ' '
 	tabwriterFlags    = 0
+	loadBalancerWidth = 16
 )
 
 // GetPrinter takes a format type, an optional format argument. It will return true
@@ -930,19 +931,26 @@ func printJobList(list *batch.JobList, w io.Writer, options PrintOptions) error
 	return nil
 }
 
-// loadBalancerStatusStringer behaves just like a string interface and converts the given status to a string.
+// loadBalancerStatusStringer behaves mostly like a string interface and converts the given status to a string.
-func loadBalancerStatusStringer(s api.LoadBalancerStatus) string {
+// `wide` indicates whether the returned value is meant for --o=wide output. If not, it's clipped to 16 bytes.
+func loadBalancerStatusStringer(s api.LoadBalancerStatus, wide bool) string {
 	ingress := s.Ingress
 	result := []string{}
 	for i := range ingress {
 		if ingress[i].IP != "" {
 			result = append(result, ingress[i].IP)
+		} else if ingress[i].Hostname != "" {
+			result = append(result, ingress[i].Hostname)
 		}
 	}
-	return strings.Join(result, ",")
+	r := strings.Join(result, ",")
+	if !wide && len(r) > loadBalancerWidth {
+		r = r[0:(loadBalancerWidth-3)] + "..."
+	}
+	return r
 }
 
-func getServiceExternalIP(svc *api.Service) string {
+func getServiceExternalIP(svc *api.Service, wide bool) string {
 	switch svc.Spec.Type {
 	case api.ServiceTypeClusterIP:
 		if len(svc.Spec.ExternalIPs) > 0 {
@@ -955,7 +963,7 @@ func getServiceExternalIP(svc *api.Service) string {
 		}
 		return "<nodes>"
 	case api.ServiceTypeLoadBalancer:
-		lbIps := loadBalancerStatusStringer(svc.Status.LoadBalancer)
+		lbIps := loadBalancerStatusStringer(svc.Status.LoadBalancer, wide)
 		if len(svc.Spec.ExternalIPs) > 0 {
 			result := append(strings.Split(lbIps, ","), svc.Spec.ExternalIPs...)
 			return strings.Join(result, ",")
@@ -982,7 +990,7 @@ func printService(svc *api.Service, w io.Writer, options PrintOptions) error {
 	namespace := svc.Namespace
 
 	internalIP := svc.Spec.ClusterIP
-	externalIP := getServiceExternalIP(svc)
+	externalIP := getServiceExternalIP(svc, options.Wide)
 
 	if options.WithNamespace {
 		if _, err := fmt.Fprintf(w, "%s\t", namespace); err != nil {
@@ -1069,7 +1077,7 @@ func printIngress(ingress *extensions.Ingress, w io.Writer, options PrintOptions
 	if _, err := fmt.Fprintf(w, "%s\t%v\t%v\t%v\t%s",
 		name,
 		formatHosts(ingress.Spec.Rules),
-		loadBalancerStatusStringer(ingress.Status.LoadBalancer),
+		loadBalancerStatusStringer(ingress.Status.LoadBalancer, options.Wide),
 		formatPorts(ingress.Spec.TLS),
 		translateTimestamp(ingress.CreationTimestamp),
 	); err != nil {

pkg/kubectl/resource_printer_test.go

@@ -706,7 +706,7 @@ func TestPrintHumanReadableService(t *testing.T) {
 		},
 		{
 			Spec: api.ServiceSpec{
-				ClusterIP: "1.2.3.4",
+				ClusterIP: "1.3.4.5",
 				Ports: []api.ServicePort{
 					{
 						Port:     80,
@@ -725,7 +725,7 @@ func TestPrintHumanReadableService(t *testing.T) {
 		},
 		{
 			Spec: api.ServiceSpec{
-				ClusterIP: "1.2.3.4",
+				ClusterIP: "1.4.5.6",
 				Type:      "LoadBalancer",
 				Ports: []api.ServicePort{
 					{
@@ -754,7 +754,7 @@ func TestPrintHumanReadableService(t *testing.T) {
 		},
 		{
 			Spec: api.ServiceSpec{
-				ClusterIP: "1.2.3.4",
+				ClusterIP: "1.5.6.7",
 				Type:      "LoadBalancer",
 				Ports: []api.ServicePort{
 					{
@@ -791,18 +791,20 @@ func TestPrintHumanReadableService(t *testing.T) {
 	}
 
 	for _, svc := range tests {
+		for _, wide := range []bool{false, true} {
 			buff := bytes.Buffer{}
-		printService(&svc, &buff, PrintOptions{false, false, false, false, false, false, []string{}})
+			printService(&svc, &buff, PrintOptions{false, false, wide, false, false, false, []string{}})
 			output := string(buff.Bytes())
 			ip := svc.Spec.ClusterIP
 			if !strings.Contains(output, ip) {
 				t.Errorf("expected to contain ClusterIP %s, but doesn't: %s", ip, output)
 			}
 
-		for _, ingress := range svc.Status.LoadBalancer.Ingress {
+			for n, ingress := range svc.Status.LoadBalancer.Ingress {
 				ip = ingress.IP
-			if !strings.Contains(output, ip) {
+				// For non-wide output, we only guarantee the first IP to be printed
-				t.Errorf("expected to contain ingress ip %s, but doesn't: %s", ip, output)
+				if (n == 0 || wide) && !strings.Contains(output, ip) {
+					t.Errorf("expected to contain ingress ip %s with wide=%v, but doesn't: %s", ip, wide, output)
 				}
 			}
 
@@ -818,6 +820,7 @@ func TestPrintHumanReadableService(t *testing.T) {
 			}
 		}
 	}
+}
 
 func TestPrintHumanReadableWithNamespace(t *testing.T) {
 	namespaceName := "testnamespace"