webhook: Allow only one instance of each HTTPRouteFilterType

Signed-off-by: Christopher M. Luciano <cmluciano@us.ibm.com>

pkg/admission/validator.go

@@ -8,10 +8,24 @@ func ValidateHTTPRoute(httpRoute v1alpha1.HTTPRoute) (bool, string, error) {
 	if len(httpRoute.Spec.Rules) == 0 {
 		return true, "", nil
 	}
+	numReqHeaderMod := 0
+	numReqMirror := 0
+	numExtRef := 0
 	for _, rule := range httpRoute.Spec.Rules {
 		if len(rule.Filters) != 0 {
-			if len(rule.Filters) > 1 {
-				return false, "HTTPRules cannot contain more than one HTTPFilter", nil
+			for _, filter := range rule.Filters {
+				switch filter.Type {
+				case v1alpha1.HTTPRouteFilterRequestHeaderModifier:
+					numReqHeaderMod++
+				case v1alpha1.HTTPRouteFilterRequestMirror:
+					numReqMirror++
+				case v1alpha1.HTTPRouteFilterExtensionRef:
+					numExtRef++
+				}
+			}
+			// Multiple filters are allowed but only 1 of each HTTPRouteFilterType
+			if numReqHeaderMod > 1 || numReqMirror > 1 || numExtRef > 1 {
+				return false, "HTTPRules cannot contain more than instance of each HTTPRouteFilterType", nil
 			}
 		}
 	}

pkg/admission/validator_test.go

@@ -170,7 +170,7 @@ func TestSAValidator_ValidateHTTPRoute(t *testing.T) {
 			wantErr:     false,
 		},
 		{
-			name: "valid httpRoute with 2 filters",
+			name: "invalid httpRoute with 2 filters",
 			hRoute: v1alpha1.HTTPRoute{
 				Spec: v1alpha1.HTTPRouteSpec{
 					Rules: []v1alpha1.HTTPRouteRule{
@@ -204,7 +204,7 @@ func TestSAValidator_ValidateHTTPRoute(t *testing.T) {
 				},
 			},
 			wantOK:      false,
-			wantMessage: "HTTPRules cannot contain more than one HTTPFilter",
+			wantMessage: "HTTPRules cannot contain more than instance of each HTTPRouteFilterType",
 			wantErr:     false,
 		},
 	}