Implement gwctl get gateways

Signed-off-by: Jongwoo Han <jongwooo.han@gmail.com>

gwctl/pkg/cmd/get/get.go

@@ -36,7 +36,7 @@ func NewGetCommand(params *utils.CmdParams) *cobra.Command {
 	flags := &getFlags{}
 
 	cmd := &cobra.Command{
-		Use:   "get {policies|policycrds|httproutes}",
+		Use:   "get {gateways|policies|policycrds|httproutes}",
 		Short: "Display one or many resources",
 		Args:  cobra.ExactArgs(1),
 		Run: func(cmd *cobra.Command, args []string) {
@@ -56,10 +56,26 @@ func runGet(args []string, params *utils.CmdParams, flags *getFlags) {
 		ns = ""
 	}
 
+	discoverer := resourcediscovery.Discoverer{
+		K8sClients:    params.K8sClients,
+		PolicyManager: params.PolicyManager,
+	}
+	gwPrinter := &printer.GatewaysPrinter{Out: params.Out}
 	policiesPrinter := &printer.PoliciesPrinter{Out: params.Out}
 	httpRoutesPrinter := &printer.HTTPRoutesPrinter{Out: params.Out}
 
 	switch kind {
+	case "gateway", "gateways":
+		filter := resourcediscovery.Filter{Namespace: ns}
+		if len(args) > 1 {
+			filter.Name = args[1]
+		}
+		resourceModel, err := discoverer.DiscoverResourcesForGateway(filter)
+		if err != nil {
+			panic(err)
+		}
+		gwPrinter.Print(resourceModel)
+
 	case "policy", "policies":
 		list := params.PolicyManager.GetPolicies()
 		policiesPrinter.Print(list)
@@ -69,10 +85,6 @@ func runGet(args []string, params *utils.CmdParams, flags *getFlags) {
 		policiesPrinter.PrintCRDs(list)
 
 	case "httproute", "httproutes":
-		discoverer := resourcediscovery.Discoverer{
-			K8sClients:    params.K8sClients,
-			PolicyManager: params.PolicyManager,
-		}
 		filter := resourcediscovery.Filter{Namespace: ns}
 		if len(args) > 1 {
 			filter.Name = args[1]

gwctl/pkg/printer/gateways.go

@@ -19,11 +19,17 @@ package printer
 import (
 	"fmt"
 	"io"
+	"strconv"
+	"strings"
+	"text/tabwriter"
+	"time"
 
 	"sigs.k8s.io/yaml"
 
 	"sigs.k8s.io/gateway-api/gwctl/pkg/policymanager"
 	"sigs.k8s.io/gateway-api/gwctl/pkg/resourcediscovery"
+
+	"k8s.io/apimachinery/pkg/util/duration"
 )
 
 type GatewaysPrinter struct {
@@ -40,6 +46,50 @@ type gatewayDescribeView struct {
 	EffectivePolicies        map[policymanager.PolicyCrdID]policymanager.Policy `json:",omitempty"`
 }
 
+func (gp *GatewaysPrinter) Print(resourceModel *resourcediscovery.ResourceModel) {
+	tw := tabwriter.NewWriter(gp.Out, 0, 0, 2, ' ', 0)
+	row := []string{"NAME", "CLASS", "ADDRESSES", "PORTS", "PROGRAMMED", "AGE"}
+	tw.Write([]byte(strings.Join(row, "\t") + "\n"))
+
+	for _, gatewayNode := range resourceModel.Gateways {
+		var addresses []string
+		for _, address := range gatewayNode.Gateway.Status.Addresses {
+			addresses = append(addresses, address.Value)
+		}
+		addressesOutput := strings.Join(addresses, ",")
+		if cnt := len(addresses); cnt > 2 {
+			addressesOutput = fmt.Sprintf("%v + %v more", strings.Join(addresses[:2], ","), cnt-2)
+		}
+
+		var ports []string
+		for _, listener := range gatewayNode.Gateway.Spec.Listeners {
+			ports = append(ports, strconv.Itoa(int(listener.Port)))
+		}
+		portsOutput := strings.Join(ports, ",")
+
+		programmedStatus := "Unknown"
+		for _, condition := range gatewayNode.Gateway.Status.Conditions {
+			if condition.Type == "Programmed" {
+				programmedStatus = string(condition.Status)
+				break
+			}
+		}
+
+		age := duration.HumanDuration(time.Since(gatewayNode.Gateway.GetCreationTimestamp().Time))
+
+		row := []string{
+			gatewayNode.Gateway.GetName(),
+			string(gatewayNode.Gateway.Spec.GatewayClassName),
+			addressesOutput,
+			portsOutput,
+			programmedStatus,
+			age,
+		}
+		tw.Write([]byte(strings.Join(row, "\t") + "\n"))
+	}
+	tw.Flush()
+}
+
 func (gp *GatewaysPrinter) PrintDescribeView(resourceModel *resourcediscovery.ResourceModel) {
 	index := 0
 	for _, gatewayNode := range resourceModel.Gateways {

gwctl/pkg/printer/gateways_test.go

@@ -19,20 +19,92 @@ package printer
 import (
 	"bytes"
 	"testing"
+	"time"
 
 	"github.com/google/go-cmp/cmp"
 	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime"
+
 	gatewayv1 "sigs.k8s.io/gateway-api/apis/v1"
 	gatewayv1alpha2 "sigs.k8s.io/gateway-api/apis/v1alpha2"
-
 	"sigs.k8s.io/gateway-api/gwctl/pkg/cmd/utils"
 	"sigs.k8s.io/gateway-api/gwctl/pkg/common"
 	"sigs.k8s.io/gateway-api/gwctl/pkg/resourcediscovery"
 )
 
+func TestGatewaysPrinter_Print(t *testing.T) {
+	objects := []runtime.Object{
+		&gatewayv1.GatewayClass{
+			ObjectMeta: metav1.ObjectMeta{
+				Name: "foo-gatewayclass",
+			},
+			Spec: gatewayv1.GatewayClassSpec{
+				ControllerName: "example.net/gateway-controller",
+				Description:    common.PtrTo("random"),
+			},
+		},
+
+		&gatewayv1.Gateway{
+			ObjectMeta: metav1.ObjectMeta{
+				Name: "foo-gateway",
+				CreationTimestamp: metav1.Time{
+					Time: time.Now().Add(-time.Second),
+				},
+			},
+			Spec: gatewayv1.GatewaySpec{
+				GatewayClassName: "foo-gatewayclass",
+				Listeners: []gatewayv1.Listener{
+					{
+						Name:     gatewayv1.SectionName("http-1"),
+						Protocol: gatewayv1.HTTPProtocolType,
+						Port:     gatewayv1.PortNumber(80),
+					},
+				},
+			},
+			Status: gatewayv1.GatewayStatus{
+				Addresses: []gatewayv1.GatewayStatusAddress{
+					{
+						Value: "10.0.0.1",
+					},
+				},
+				Conditions: []metav1.Condition{
+					{
+						Type:   "Programmed",
+						Status: metav1.ConditionTrue,
+					},
+				},
+			},
+		},
+	}
+
+	params := utils.MustParamsForTest(t, common.MustClientsForTest(t, objects...))
+	discoverer := resourcediscovery.Discoverer{
+		K8sClients:    params.K8sClients,
+		PolicyManager: params.PolicyManager,
+	}
+	resourceModel, err := discoverer.DiscoverResourcesForGateway(resourcediscovery.Filter{})
+	if err != nil {
+		t.Fatalf("Failed to construct resourceModel: %v", resourceModel)
+	}
+
+	gp := &GatewaysPrinter{
+		Out: params.Out,
+	}
+	gp.Print(resourceModel)
+
+	got := params.Out.(*bytes.Buffer).String()
+	want := `
+NAME         CLASS             ADDRESSES  PORTS  PROGRAMMED  AGE
+foo-gateway  foo-gatewayclass  10.0.0.1   80     True        1s
+`
+
+	if diff := cmp.Diff(common.YamlString(want), common.YamlString(got), common.YamlStringTransformer); diff != "" {
+		t.Errorf("Unexpected diff\ngot=\n%v\nwant=\n%v\ndiff (-want +got)=\n%v", got, want, diff)
+	}
+}
+
 func TestGatewaysPrinter_PrintDescribeView(t *testing.T) {
 	objects := []runtime.Object{
 		&gatewayv1.GatewayClass{