KEP-2365: documentation for namespace-scoped parameters reference

content/en/docs/concepts/services-networking/ingress.md

@@ -220,7 +220,19 @@ of the controller that should implement the class.
 {{< codenew file="service/networking/external-lb.yaml" >}}
 
 IngressClass resources contain an optional parameters field. This can be used to
-reference additional configuration for this class.
+reference additional implementation-specific configuration for this class.
+
+#### Namespace-scoped parameters
+
+{{< feature-state for_k8s_version="v1.21" state="alpha" >}}
+
+`Parameters` field has a `scope` and `namespace` field that can be used to
+reference a namespace-specific resource for configuration of an Ingress class.
+`Scope` field defaults to `Cluster`, meaning, the default is cluster-scoped
+resource. Setting `Scope` to `Namespace` and setting the `Namespace` field
+will reference a paramters resource in a specific namespace:
+
+{{< codenew file="service/networking/namespaced-params.yaml" >}}
 
 ### Deprecated annotation
 

content/en/docs/reference/command-line-tools-reference/feature-gates.md

@@ -124,6 +124,7 @@ different Kubernetes components.
 | `HPAScaleToZero` | `false` | Alpha | 1.16 | |
 | `HugePageStorageMediumSize` | `false` | Alpha | 1.18 | 1.18 |
 | `HugePageStorageMediumSize` | `true` | Beta | 1.19 | |
+| `IngressClassNamespacedParams` | `false` | Alpha | 1.21 | |
 | `IPv6DualStack` | `false` | Alpha | 1.15 | 1.20 |
 | `IPv6DualStack` | `true` | Beta | 1.21 | |
 | `KubeletCredentialProviders` | `false` | Alpha | 1.20 | |
@@ -642,6 +643,9 @@ Each feature gate is designed for enabling/disabling a specific feature:
   immutable for better safety and performance.
 - `IndexedJob`: Allows the [Job](/docs/concepts/workloads/controllers/job/)
   controller to manage Pod completions per completion index.
+- `IngressClassNamespacedParams`: Allow namespace-scoped parameters reference in
+  `IngressClass` resouce. This feature adds two fields - `Scope` and `Namespace`
+  to `IngressClass.spec.parameters`.
 - `IPv6DualStack`: Enable [dual stack](/docs/concepts/services-networking/dual-stack/)
   support for IPv6.
 - `KubeletConfigFile` (*deprecated*): Enable loading kubelet configuration from

content/en/examples/service/networking/namespaced-params.yaml

@@ -0,0 +1,12 @@
+apiVersion: networking.k8s.io/v1
+kind: IngressClass
+metadata:
+  name: external-lb
+spec:
+  controller: example.com/ingress-controller
+  parameters:
+    apiGroup: k8s.example.com
+    kind: IngressParameters
+    name: external-lb
+    namespace: external-configuration
+    scope: Namespace