Allow empty HTTPRoute hostnames

If an HTTPRoute didn't supply any hostnames, then we wouldn't attach it to any listeners. This fixes that issue and uses the wildcard hostname if a listener doesn't supply a hostname, otherwise just use the hostnames of the listeners.

Author: sjberman

internal/state/dataplane/configuration.go

@@ -266,13 +266,7 @@ func (hpr *hostPathRules) upsertListener(l *graph.Listener) {
 	}
 
 	for routeNsName, r := range l.Routes {
-		var hostnames []string
-
-		for _, h := range r.Source.Spec.Hostnames {
-			if _, exist := l.AcceptedHostnames[string(h)]; exist {
-				hostnames = append(hostnames, string(h))
-			}
-		}
+		hostnames := getHostnames(r, l)
 
 		for _, h := range hostnames {
 			if prevListener, exists := hpr.listenersForHost[h]; exists {
@@ -333,6 +327,23 @@ func (hpr *hostPathRules) upsertListener(l *graph.Listener) {
 	}
 }
 
+func getHostnames(r *graph.Route, l *graph.Listener) []string {
+	var hostnames []string
+	for _, h := range r.Source.Spec.Hostnames {
+		if _, exist := l.AcceptedHostnames[string(h)]; exist {
+			hostnames = append(hostnames, string(h))
+		}
+	}
+
+	if len(r.Source.Spec.Hostnames) == 0 {
+		for hostname := range l.AcceptedHostnames {
+			hostnames = append(hostnames, hostname)
+		}
+	}
+
+	return hostnames
+}
+
 func (hpr *hostPathRules) buildServers() []VirtualServer {
 	servers := make([]VirtualServer, 0, len(hpr.rulesPerHost)+len(hpr.httpsListeners))
 

internal/state/dataplane/configuration_test.go

@@ -217,13 +217,21 @@ func TestBuildConfiguration(t *testing.T) {
 		pathAndType{path: "/valid", pathType: prefix}, pathAndType{path: invalidMatchesPath, pathType: prefix},
 	)
 
-	hr7, hr7Groups, routeHR7 := createTestResources(
+	hr7, expHR7Groups, routeHR7 := createTestResources(
 		"hr-7",
 		"foo.example.com",
 		"listener-80-1",
 		pathAndType{path: "/valid", pathType: prefix}, pathAndType{path: "/valid", pathType: v1beta1.PathMatchExact},
 	)
 
+	hrNoHost, expHRNoHostGroups, routeNoHost := createTestResources(
+		"route-no-host",
+		"",
+		"listener-80-1",
+		pathAndType{path: "/", pathType: prefix},
+	)
+	routeNoHost.Source.Spec.Hostnames = []v1beta1.Hostname{}
+
 	httpsHR1, expHTTPSHR1Groups, httpsRouteHR1 := createTestResources(
 		"https-hr-1",
 		"foo.example.com",
@@ -516,6 +524,60 @@ func TestBuildConfiguration(t *testing.T) {
 			},
 			msg: "one http listener with two routes for different hostnames",
 		},
+		{
+			graph: &graph.Graph{
+				GatewayClass: &graph.GatewayClass{
+					Source: &v1beta1.GatewayClass{},
+					Valid:  true,
+				},
+				Gateway: &graph.Gateway{
+					Source: &v1beta1.Gateway{},
+					Listeners: map[string]*graph.Listener{
+						"listener-80-1": {
+							Source: listener80,
+							Valid:  true,
+							Routes: map[types.NamespacedName]*graph.Route{
+								{Namespace: "test", Name: "route-no-host"}: routeNoHost,
+							},
+							AcceptedHostnames: map[string]struct{}{
+								wildcardHostname: {},
+							},
+						},
+					},
+				},
+				Routes: map[types.NamespacedName]*graph.Route{
+					{Namespace: "test", Name: "route-no-host"}: routeNoHost,
+				},
+			},
+			expConf: Configuration{
+				HTTPServers: []VirtualServer{
+					{
+						IsDefault: true,
+					},
+					{
+						Hostname: wildcardHostname,
+						PathRules: []PathRule{
+							{
+								Path:     "/",
+								PathType: PathTypePrefix,
+								MatchRules: []MatchRule{
+									{
+										MatchIdx:     0,
+										RuleIdx:      0,
+										BackendGroup: expHRNoHostGroups[0],
+										Source:       hrNoHost,
+									},
+								},
+							},
+						},
+					},
+				},
+				SSLServers:    []VirtualServer{},
+				Upstreams:     []Upstream{fooUpstream},
+				BackendGroups: []BackendGroup{expHRNoHostGroups[0]},
+			},
+			msg: "one listener and route without hostnames",
+		},
 		{
 			graph: &graph.Graph{
 				GatewayClass: &graph.GatewayClass{
@@ -1074,7 +1136,7 @@ func TestBuildConfiguration(t *testing.T) {
 									{
 										MatchIdx:     0,
 										RuleIdx:      1,
-										BackendGroup: hr7Groups[1],
+										BackendGroup: expHR7Groups[1],
 										Source:       hr7,
 									},
 								},
@@ -1086,7 +1148,7 @@ func TestBuildConfiguration(t *testing.T) {
 									{
 										MatchIdx:     0,
 										RuleIdx:      0,
-										BackendGroup: hr7Groups[0],
+										BackendGroup: expHR7Groups[0],
 										Source:       hr7,
 									},
 								},
@@ -1096,7 +1158,7 @@ func TestBuildConfiguration(t *testing.T) {
 				},
 				SSLServers:    []VirtualServer{},
 				Upstreams:     []Upstream{fooUpstream},
-				BackendGroups: []BackendGroup{hr7Groups[0], hr7Groups[1]},
+				BackendGroups: []BackendGroup{expHR7Groups[0], expHR7Groups[1]},
 			},
 			msg: "duplicate paths with different types",
 		},

internal/state/graph/httproute.go

@@ -13,6 +13,8 @@ import (
 	"github.com/nginxinc/nginx-kubernetes-gateway/internal/state/validation"
 )
 
+const wildcardHostname = "~^"
+
 // Rule represents a rule of an HTTPRoute.
 type Rule struct {
 	// BackendRefs is a list of BackendRefs for the rule.
@@ -380,6 +382,13 @@ func findValidListeners(sectionName string, listeners map[string]*Listener) ([]*
 func findAcceptedHostnames(listenerHostname *v1beta1.Hostname, routeHostnames []v1beta1.Hostname) []string {
 	hostname := getHostname(listenerHostname)
 
+	if len(routeHostnames) == 0 {
+		if hostname == "" {
+			return []string{wildcardHostname}
+		}
+		return []string{hostname}
+	}
+
 	match := func(h v1beta1.Hostname) bool {
 		if hostname == "" {
 			return true

internal/state/graph/httproute_test.go

@@ -1008,6 +1008,18 @@ func TestFindAcceptedHostnames(t *testing.T) {
 			expected:         []string{"foo.example.com", "bar.example.com"},
 			msg:              "nil listener hostname",
 		},
+		{
+			listenerHostname: &listenerHostnameFoo,
+			routeHostnames:   nil,
+			expected:         []string{"foo.example.com"},
+			msg:              "route has empty hostnames",
+		},
+		{
+			listenerHostname: nil,
+			routeHostnames:   nil,
+			expected:         []string{wildcardHostname},
+			msg:              "both listener and route have empty hostnames",
+		},
 	}
 
 	for _, test := range tests {