feature(parser): consolidation of multiple HTTPRouteMatch objects into single kong.Route (#3060)

* feat(parser): consolidation of multiple HTTPRouteMatch objects into single kong.Route

Co-authored-by: Travis Raines <[email protected]>

Author: jrsmroz

CHANGELOG.md

@@ -68,13 +68,31 @@ Adding a new version? You'll need three changes:
 ### Added
 
 - Added `HTTPRoute` support for `CombinedRoutes` feature. When enabled,
-  this changes how `HTTPRoute` resources are translated so that `HTTPRouteRule`
-  resources are combined when they have same backends references. This change
-  does not functionally impact routing: requests that went to a given Service
-  using the original method still go to the same Service in the new method.
+  `HTTPRoute.HTTPRouteRule` objects with identical `backendRefs` generate a 
+  single Kong service instead of a service per rule, and 
+  `HTTPRouteRule.HTTPRouteMatche` objects using the same `backendRefs` can be 
+  consolidated into a single Kong route instead of always creating a route per 
+  match, reducing configuration size.
+  The following limitations apply:
+  - `HTTPRouteRule` objects cannot be consolidated into a single Kong Service 
+    if they belong to different `HTTPRoute`.
+  - `HTTPRouteRule` objects cannot be consolidated into a single Kong Service 
+    if they have different `HTTPRouteRule.HTTPBackendRef[]` objects. The order
+    of the backend references is not important.
+  - `HTTPRouteMatch` objects cannot be consolidated into a single Kong Route
+    if parent `HTTPRouteRule` objects cannot be consolidated into a single Kong Service.
+  - `HTTPRouteMatch` objects cannot be consolidated into a single Kong Route
+    if parent `HTTPRouteRule` objects have different `HTTPRouteRule.HTTPRouteFilter[]` filters.
+  - `HTTPRouteMatch` objects cannot be consolidated into a single Kong Route 
+    if they have different matching spec (`HTTPHeaderMatch.Headers`, `HTTPHeaderMatch.QueryParams`, 
+    `HTTPHeaderMatch.Method`). Different `HTTPHeaderMatch.Path` paths between 
+    `HTTPRouteMatch[]` objects does not prevent consolidation.
+  This change does not functionally impact routing: requests that went to a given Service
+  using the original method still go to the same Service when `CombinedRoutes` is enabled.
   [#3008](https://github.com/Kong/kubernetes-ingress-controller/pull/3008)
-- Added `--cache-sync-timeout` flag allowing to change the default controllers'
-  cache synchronisation timeout.
+  [#3060]https://github.com/Kong/kubernetes-ingress-controller/pull/3060)
+- Added `--cache-sync-timeout` flag allowing to change the default controllers' 
+  cache synchronisation timeout. 
   [#3013](https://github.com/Kong/kubernetes-ingress-controller/pull/3013)
 - Secrets validation introduced: CA certificates won't be synchronized
   to Kong if the certificate is expired.

internal/dataplane/parser/translate_httproute.go

@@ -78,27 +78,25 @@ func (p *Parser) ingressRulesFromHTTPRoute(result *ingressRules, httproute *gate
 // ingressRulesFromHTTPRouteWithCombinedServiceRoutes generates a set of proto-Kong routes (ingress rules) from an HTTPRoute.
 // If multiple rules in the HTTPRoute use the same Service, it combines them into a single Kong route.
 func (p *Parser) ingressRulesFromHTTPRouteWithCombinedServiceRoutes(httproute *gatewayv1beta1.HTTPRoute, result *ingressRules) error {
-	for _, translationMeta := range translators.TranslateHTTPRoute(httproute) {
+	for _, kongServiceTranslation := range translators.TranslateHTTPRoute(httproute) {
 		// HTTPRoute uses a wrapper HTTPBackendRef to add optional filters to its BackendRefs
-		backendRefs := httpBackendRefsToBackendRefs(translationMeta.BackendRefs)
+		backendRefs := httpBackendRefsToBackendRefs(kongServiceTranslation.BackendRefs)
 
-		// use the original index of the first rule that uses this service as the rule number
-		firstCombinedRuleNum := translationMeta.RulesNumbers[0]
+		serviceName := kongServiceTranslation.Name
 
 		// create a service and attach the routes to it
-		service, err := generateKongServiceFromBackendRefWithRuleNumber(p.logger, p.storer, result, httproute, firstCombinedRuleNum, "http", backendRefs...)
+		service, err := generateKongServiceFromBackendRefWithName(p.logger, p.storer, result, serviceName, httproute, "http", backendRefs...)
 		if err != nil {
 			return err
 		}
 
 		// generate the routes for the service and attach them to the service
-		for j, rule := range translationMeta.Rules {
-			ruleNumber := translationMeta.RulesNumbers[j]
-			routes, err := generateKongRoutesFromHTTPRouteRule(httproute, ruleNumber, rule, p.flagEnabledRegexPathPrefix)
+		for _, kongRouteTranslation := range kongServiceTranslation.KongRoutes {
+			route, err := generateKongRouteFromTranslation(httproute, kongRouteTranslation, p.flagEnabledRegexPathPrefix)
 			if err != nil {
 				return err
 			}
-			service.Routes = append(service.Routes, routes...)
+			service.Routes = append(service.Routes, route)
 		}
 
 		// cache the service to avoid duplicates in further loop iterations
@@ -219,6 +217,30 @@ func generateKongRoutesFromHTTPRouteRule(
 	return routes, nil
 }
 
+func generateKongRouteFromTranslation(
+	httproute *gatewayv1beta1.HTTPRoute,
+	translation translators.KongRouteTranslation,
+	addRegexPrefix bool,
+) (kongstate.Route, error) {
+	// gather the k8s object information and hostnames from the httproute
+	objectInfo := util.FromK8sObject(httproute)
+
+	// get the hostnames from the HTTPRoute
+	hostnames := getHTTPRouteHostnamesAsSliceOfStringPointers(httproute)
+
+	// generate kong plugins from rule.filters
+	plugins := generatePluginsFromHTTPRouteFilters(translation.Filters)
+
+	return generateKongRouteFromHTTPRouteMatches(
+		translation.Name,
+		translation.Matches,
+		objectInfo,
+		hostnames,
+		plugins,
+		addRegexPrefix,
+	)
+}
+
 // generateKongRouteFromHTTPRouteMatches converts an HTTPRouteMatches to a Kong Route object.
 // This function assumes that the HTTPRouteMatches share the query params, headers and methods.
 func generateKongRouteFromHTTPRouteMatches(