KIC: feat: add introduction about combined service from different httproutes

app/_data/docs_nav_kic_3.4.x.yml

@@ -221,3 +221,5 @@ items:
         url: /reference/required-permissions
       - text: Categories of Failures
         url: /reference/failure-modes
+      - text: Combining Services From Different HTTPRoutes
+        url: /reference/combined-services-from-different-httproutes

app/_src/kubernetes-ingress-controller/reference/combined-services-from-different-httproutes.md

@@ -0,0 +1,91 @@
+---
+title: Combining Services From Different HTTPRoutes 
+type: reference
+purpose: |
+  Introduce the feature gate to consolidate {{site.base_gateway}} services by combining rules from different HTTPRoutes
+alpha: true
+---
+
+Similar to the consolidation behavior implemented for `Ingress` resources, {{ site.kic_product_name }} now supports the consolidation of rules from different `HTTPRoute` resources. When multiple `HTTPRoute`s specify the same combination of backend services, they will be translated into a single {{ site.base_gateway }} service, effectively reducing the total number of {{ site.base_gateway }} services required.
+
+## How to Enable the Feature?
+The feature is enabled when the feature gate `CombinedServicesFromDifferentHTTPRoutes` is set to `true`. You can refer to the [feature gate reference](/kubernetes-ingress-controller/{{page.release}}/reference/feature-gates) to know more about the feature gates.
+
+## What Does the Feature Gate Do?
+When the feature is enabled, The rules having the same combination of backend services (combination of namespace, name, port and weight in `backendRefs` of rules)
+in all `HTTPRoute`s within the same namespace will be translated to one {{site.base_gateway}} service.
+
+## How the Translation is Done?
+
+The names of the translated {{site.base_gateway}} service will be changed when the feature is enabled. Instead of generating names from source `HTTPRoute`
+and rules, the {{site.base_gateway}} service names will be generated from the consolidated backends.
+
+### Compute Service Name
+
+Names of {{site.base_gateway}} services are computed from the namespace, name, port and weight(if specified). The pattern of names is
+`httproute.<namespace>.svc.<backend_ns>.<backend_name>.<backend_port>.[backend_weight]_[next_backends]...` where:
+ - `namespace` is the namespace of the `HTTPRoute`s.
+ - `backend_ns` is the namespace of the first backend service.
+ - `backend_name` is the name of the first backend service.
+ - `backend_port` is the port number of the first backend service.
+ - `backend_weight` is the weight of the first backend service if specified.
+ - `next_backends` are sections computed from other backend services. Backend services are sorted by the namespace and name.
+
+ In addition, When the computed name from the method above is longer than 512 characters (the limit of service name length in {{site.konnect_short_name}}), the service name is trimmed using the following rules:
+- Only use `backend_ns`, `backend_name`,`backend_port`, `backend_weight` of the first backend service,
+- Append the `_combined.<hash>` to make sure that the name is unique. Where `hash` is the SHA256 digest of the computed service name.
+
+For example, the following two `HTTPRoute`s with rules pointing to the same backends with the same ports and weights:
+
+```yaml
+apiVersion: gateway.networking.k8s.io/v1
+kind: HTTPRoute
+metadata:
+  name: httproute-consolidated-1
+  namespace: default
+spec:
+  parentRefs:
+  - name: kong
+  rules:
+  - matches:
+    - path:
+        type: PathPrefix
+        value: /httproute-testing
+    backendRefs:
+    - name: echo-1
+      kind: Service
+      port: 80
+      weight: 75
+    - name: echo-2
+      kind: Service
+      port: 8080
+      weight: 25
+---
+apiVersion: gateway.networking.k8s.io/v1
+kind: HTTPRoute
+metadata:
+  name: httproute-consolidated-2
+  namespace: default
+spec:
+  parentRefs:
+  - name: kong
+  rules:
+  - matches:
+    - path:
+        type: PathPrefix
+        value: /httproute-testing
+    backendRefs:
+    - name: echo-1
+      kind: Service
+      port: 80
+      weight: 75
+    - name: echo-2
+      kind: Service
+      port: 8080
+      weight: 25
+```
+
+When the feature is disabled (which is default), the rules in the two `HTTPRoutes` are translated to two distinct {{site.base_gateway}} services:
+`httproute.default.httproute-consolidated-1.0` and `httproute.default.httproute-consolidated-2.0`.
+
+When the feature is enabled, The two rules from the two `HTTPRoute`s `httproute-consolidated-1` and `httproute-consolidated-2` result in a single {{site.base_gateway}} service named `httproute.default.svc.default.echo-1.80.75.default.echo-2.80.25`.

app/_src/kubernetes-ingress-controller/reference/feature-gates.md

@@ -29,6 +29,9 @@ The same definitions of `feature gates` and `feature stages` from upstream Kuber
 | KongCustomEntity           | `true`  | Beta  | 3.3.0  | 3.4.0 |
 | KongCustomEntity           | `true`  | GA    | 3.4.0  | TBD   |
 {% endif_version %}
+{% if_version gte:3.4.x %}
+| CombinedServicesFromDifferentHTTPRoutes  | `false` | Alpha | 3.4.0  | TBD   |
+{% endif_version %}
 
 ## Using feature gates
 
@@ -91,3 +94,14 @@ private keys in `Certificate` entities and `Consumer` entities' credentials.
 > **Warning:** `KongPlugin`'s and `KongClusterPlugin`'s `config` fields are not sanitized. If you have sensitive information
 > in your `KongPlugin`'s `config` field, it will be sent to Konnect as is. To avoid that, please consider using
 > [KongVault](/kubernetes-ingress-controller/{{page.release}}/reference/custom-resources/#kongvault).
+
+{% if_version gte:3.4.x %}
+### CombinedServicesFromDifferentHTTPRoutes
+
+The `CombinedServicesFromDifferentHTTPRoutes` feature enables translating `HTTPRoute` rules
+with the same set of backends (combination of namespace, name, port and weight) from different `HTTPRoute`s in the same namespace
+into a single {{site.base_gateway}} service. Enabling the feature gate can reduce the number of translated {{site.base_gateway}} services.
+
+The names of {{site.base_gateway}} services will change if the feature gate is enabled.
+You can refer to the [reference page](/kubernetes-ingress-controller/{{page.release}}/reference/combined-services-from-different-httproutes) for further details.
+{% endif_version %}