fix: generate routes with hostname match only when GRPCRoute rule does not have matches

CHANGELOG.md

@@ -79,6 +79,9 @@ Adding a new version? You'll need three changes:
 - Display Service ports on generated Kong services, instead of a static default
   value. This change is cosmetic only.
   [#4503](https://github.com/Kong/kubernetes-ingress-controller/pull/4503)
+- Create routes that match any service and method for `GRPCRoute` rules with no
+  matches.
+  [#4512](https://github.com/Kong/kubernetes-ingress-controller/issues/4512)
 
 ## [2.11.0]
 

internal/dataplane/parser/translate_grpcroute.go

@@ -53,13 +53,13 @@ func (p *Parser) ingressRulesFromGRPCRoutes() ingressRules {
 }
 
 func (p *Parser) ingressRulesFromGRPCRoute(result *ingressRules, grpcroute *gatewayv1alpha2.GRPCRoute) error {
+	// validate the grpcRoute before it gets translated
+	if err := validateGRPCRoute(grpcroute); err != nil {
+		return err
+	}
 	// first we grab the spec and gather some metdata about the object
 	spec := grpcroute.Spec
 
-	if len(spec.Rules) == 0 {
-		return translators.ErrRouteValidationNoRules
-	}
-
 	// each rule may represent a different set of backend services that will be accepting
 	// traffic, so we make separate routes and Kong services for every present rule.
 	for ruleNumber, rule := range spec.Rules {
@@ -97,11 +97,9 @@ func (p *Parser) ingressRulesFromGRPCRoutesUsingExpressionRoutes(grpcRoutes []*g
 	// after they are translated, register the success event in the parser.
 	translatedGRPCRoutes := []*gatewayv1alpha2.GRPCRoute{}
 	for _, grpcRoute := range grpcRoutes {
-		if len(grpcRoute.Spec.Rules) == 0 {
-			p.registerTranslationFailure(
-				translators.ErrRouteValidationNoRules.Error(),
-				grpcRoute,
-			)
+		// validate the GRPCRoute before it gets split by hostnames and matches.
+		if err := validateGRPCRoute(grpcRoute); err != nil {
+			p.registerTranslationFailure(err.Error(), grpcRoute)
 			continue
 		}
 		splitGRPCRouteMatches = append(splitGRPCRouteMatches, translators.SplitGRPCRoute(grpcRoute)...)
@@ -164,3 +162,19 @@ func grpcBackendRefsToBackendRefs(grpcBackendRef []gatewayv1alpha2.GRPCBackendRe
 	}
 	return backendRefs
 }
+
+func validateGRPCRoute(grpcRoute *gatewayv1alpha2.GRPCRoute) error {
+	if len(grpcRoute.Spec.Hostnames) == 0 {
+		if len(grpcRoute.Spec.Rules) == 0 {
+			return translators.ErrRouteValidationNoRules
+		}
+		// REVIEW: remove this to generate a "catch-all" route from rule with no matches and no hostnames in its parent GRPCRoute.
+		for _, rule := range grpcRoute.Spec.Rules {
+			if len(rule.Matches) == 0 {
+				return translators.ErrRouteValidationNoMatchRulesOrHostnamesSpecified
+			}
+		}
+	}
+
+	return nil
+}

internal/dataplane/parser/translate_grpcroute_test.go

@@ -328,6 +328,24 @@ func TestIngressRulesFromGRPCRoutesUsingExpressionRoutes(t *testing.T) {
 					},
 					Spec: gatewayv1alpha2.GRPCRouteSpec{},
 				},
+				{
+					TypeMeta: grpcRouteTypeMeta,
+					ObjectMeta: metav1.ObjectMeta{
+						Namespace: "default",
+						Name:      "grpcroute-no-hostnames-no-matches",
+					},
+					Spec: gatewayv1alpha2.GRPCRouteSpec{
+						Rules: []gatewayv1alpha2.GRPCRouteRule{
+							{
+								BackendRefs: []gatewayv1alpha2.GRPCBackendRef{
+									{
+										BackendRef: builder.NewBackendRef("service0").WithPort(80).Build(),
+									},
+								},
+							},
+						},
+					},
+				},
 			},
 			expectedKongServices: []kongstate.Service{
 				{
@@ -361,6 +379,14 @@ func TestIngressRulesFromGRPCRoutesUsingExpressionRoutes(t *testing.T) {
 							Name:      "grpcroute-no-rules",
 						},
 					}),
+				newResourceFailure(translators.ErrRouteValidationNoMatchRulesOrHostnamesSpecified.Error(),
+					&gatewayv1alpha2.GRPCRoute{
+						TypeMeta: grpcRouteTypeMeta,
+						ObjectMeta: metav1.ObjectMeta{
+							Namespace: "default",
+							Name:      "grpcroute-no-hostnames-no-matches",
+						},
+					}),
 			},
 		},
 	}

internal/dataplane/parser/translators/grpcroute.go

@@ -48,6 +48,25 @@ func GenerateKongRoutesFromGRPCRouteRule(
 	// gather the k8s object information and hostnames from the grpcroute
 	ingressObjectInfo := util.FromK8sObject(grpcroute)
 
+	// generate a route to match hostnames only if there is no match in the rule.
+	if len(rule.Matches) == 0 {
+		routeName := fmt.Sprintf(
+			"grpcroute.%s.%s.%d.0",
+			grpcroute.Namespace,
+			grpcroute.Name,
+			ruleNumber,
+		)
+		r := kongstate.Route{
+			Ingress: ingressObjectInfo,
+			Route: kong.Route{
+				Name:      kong.String(routeName),
+				Protocols: kong.StringSlice("grpc", "grpcs"),
+			},
+		}
+		r.Hosts = getGRPCRouteHostnamesAsSliceOfStringPointers(grpcroute)
+		return []kongstate.Route{r}
+	}
+
 	for matchNumber, match := range rule.Matches {
 		routeName := fmt.Sprintf(
 			"grpcroute.%s.%s.%d.%d",

internal/dataplane/parser/translators/grpcroute_atc.go

@@ -29,6 +29,28 @@ func GenerateKongExpressionRoutesFromGRPCRouteRule(grpcroute *gatewayv1alpha2.GR
 	// gather the k8s object information and hostnames from the grpcroute
 	ingressObjectInfo := util.FromK8sObject(grpcroute)
 
+	// generate a route to match hostnames only if there is no match in the rule.
+	if len(rule.Matches) == 0 {
+		routeName := fmt.Sprintf(
+			"grpcroute.%s.%s.%d.0",
+			grpcroute.Namespace,
+			grpcroute.Name,
+			ruleNumber,
+		)
+		r := kongstate.Route{
+			Ingress: ingressObjectInfo,
+			Route: kong.Route{
+				Name: kong.String(routeName),
+			},
+			ExpressionRoutes: true,
+		}
+		hostnames := getGRPCRouteHostnamesAsSliceOfStrings(grpcroute)
+		// assign an empty match to generate matchers by only hostnames and annotations.
+		matcher := generateMathcherFromGRPCMatch(gatewayv1alpha2.GRPCRouteMatch{}, hostnames, ingressObjectInfo.Annotations)
+		atc.ApplyExpression(&r.Route, matcher, 1)
+		return []kongstate.Route{r}
+	}
+
 	for matchNumber, match := range rule.Matches {
 		routeName := fmt.Sprintf(
 			"grpcroute.%s.%s.%d.%d",
@@ -168,6 +190,16 @@ func SplitGRPCRoute(grpcroute *gatewayv1alpha2.GRPCRoute) []SplitGRPCRouteMatch
 	splitMatches := []SplitGRPCRouteMatch{}
 	splitGRPCRouteByMatch := func(hostname string) {
 		for ruleIndex, rule := range grpcroute.Spec.Rules {
+			// split out a match with only the hostname (non-empty only) when there are no matches in rule.
+			if len(rule.Matches) == 0 {
+				splitMatches = append(splitMatches, SplitGRPCRouteMatch{
+					Source:     grpcroute,
+					Hostname:   hostname,
+					Match:      gatewayv1alpha2.GRPCRouteMatch{}, // empty grpcRoute match with ALL nil fields
+					RuleIndex:  ruleIndex,
+					MatchIndex: 0,
+				})
+			}
 			for matchIndex, match := range rule.Matches {
 				splitMatches = append(splitMatches, SplitGRPCRouteMatch{
 					Source:     grpcroute,

internal/dataplane/parser/translators/grpcroute_atc_test.go

@@ -193,6 +193,29 @@ func TestGenerateKongExpressionRoutesFromGRPCRouteRule(t *testing.T) {
 				},
 			},
 		},
+		{
+			name:       "single hostname with no match",
+			objectName: "hostname-only",
+			hostnames:  []string{"foo.com"},
+			rule: gatewayv1alpha2.GRPCRouteRule{
+				Matches: []gatewayv1alpha2.GRPCRouteMatch{},
+			},
+			expectedRoutes: []kongstate.Route{
+				{
+					Ingress: util.K8sObjectInfo{
+						Name:             "hostname-only",
+						Namespace:        "default",
+						GroupVersionKind: grpcRouteGVK,
+					},
+					ExpressionRoutes: true,
+					Route: kong.Route{
+						Name:       kong.String("grpcroute.default.hostname-only.0.0"),
+						Expression: kong.String(`http.host == "foo.com"`),
+						Priority:   kong.Int(1),
+					},
+				},
+			},
+		},
 	}
 
 	for _, tc := range testCases {
@@ -368,6 +391,24 @@ func TestSplitGRPCRoute(t *testing.T) {
 				},
 			},
 		},
+		{
+			TypeMeta: grpcRouteTypeMeta,
+			ObjectMeta: metav1.ObjectMeta{
+				Namespace: "default",
+				Name:      "grpcroute-multiple-hostnames-no-match",
+			},
+			Spec: gatewayv1alpha2.GRPCRouteSpec{
+				Hostnames: []gatewayv1alpha2.Hostname{
+					gatewayv1alpha2.Hostname("pets.com"),
+					gatewayv1alpha2.Hostname("pets.net"),
+				},
+				Rules: []gatewayv1alpha2.GRPCRouteRule{
+					{
+						BackendRefs: namesToBackendRefs([]string{"listpets"}),
+					},
+				},
+			},
+		},
 	}
 
 	testCases := []struct {
@@ -442,6 +483,26 @@ func TestSplitGRPCRoute(t *testing.T) {
 				},
 			},
 		},
+		{
+			name:      "multiple hostnames and no match",
+			grpcRoute: testGRPCRoutes[3],
+			expectedSplitMatches: []SplitGRPCRouteMatch{
+				{
+					Source:     testGRPCRoutes[3],
+					Hostname:   string(testGRPCRoutes[3].Spec.Hostnames[0]),
+					Match:      gatewayv1alpha2.GRPCRouteMatch{},
+					RuleIndex:  0,
+					MatchIndex: 0,
+				},
+				{
+					Source:     testGRPCRoutes[3],
+					Hostname:   string(testGRPCRoutes[3].Spec.Hostnames[1]),
+					Match:      gatewayv1alpha2.GRPCRouteMatch{},
+					RuleIndex:  0,
+					MatchIndex: 0,
+				},
+			},
+		},
 	}
 
 	for i, tc := range testCases {

internal/dataplane/parser/translators/grpcroute_test.go

@@ -265,6 +265,29 @@ func TestGenerateKongRoutesFromGRPCRouteRule(t *testing.T) {
 				},
 			},
 		},
+		{
+			name:               "single hostname, no matches",
+			objectName:         "hostname-only",
+			annotations:        map[string]string{},
+			hostnames:          []string{"foo.com"},
+			rule:               gatewayv1alpha2.GRPCRouteRule{},
+			prependRegexPrefix: true,
+			expectedRoutes: []kongstate.Route{
+				{
+					Ingress: util.K8sObjectInfo{
+						Name:             "hostname-only",
+						Namespace:        "default",
+						Annotations:      map[string]string{},
+						GroupVersionKind: grpcRouteGVK,
+					},
+					Route: kong.Route{
+						Name:      kong.String("grpcroute.default.hostname-only.0.0"),
+						Protocols: kong.StringSlice("grpc", "grpcs"),
+						Hosts:     kong.StringSlice("foo.com"),
+					},
+				},
+			},
+		},
 	}
 
 	for _, tc := range testCases {