Add zone-sync ConfigMap Keys to docs (#7434)

Author: AlexFenlon

site/content/configuration/global-configuration/configmap-resource.md

@@ -180,6 +180,26 @@ For more information, view the [VirtualServer and VirtualServerRoute resources](
 
 ---
 
+### Zone Sync
+
+{{< note >}} 
+If you previously installed OIDC or used `zone_sync` in the stream-snippets in [v4.0.1](https://github.com/nginx/kubernetes-ingress/tree/v4.0.1) or earlier, and you plan to enable the `zone-sync` ConfigMap key, please remove `zone_sync` from the old [stream-snippets](https://github.com/nginx/kubernetes-ingress/blob/v4.0.1/examples/custom-resources/oidc/nginx-config.yaml#L7) Otherwise, NGINX Plus will encounter duplicate directive error `[emerg] 13#13: "zone_sync" directive is duplicate in /etc/nginx/nginx.conf:164`.
+Once upgraded, remove the [old headless service](https://github.com/nginx/kubernetes-ingress/blob/v4.0.1/examples/custom-resources/oidc/nginx-ingress-headless.yaml) deployed for OIDC.
+{{< /note >}} 
+
+
+{{<bootstrap-table "table table-striped table-bordered table-responsive">}}
+|ConfigMap Key | Description | Default | Example |
+| ---| ---| ---| --- |
+|*zone-sync* | Enables zone synchronization between NGINX Ingress Controller Pods. This autogenerates a [zone_sync_server](https://nginx.org/en/docs/stream/ngx_stream_zone_sync_module.html#zone_sync_server) and a headless service using the `ReplicaSet` or `DaemonSet` name. Please note that this headless service will be automatically cleaned up when uninstalling via Helm or by removing the value from the ConfigMap. The headless service will need to be manually removed if the `controller.customConfigMap` value is set via Helm or the deployment is uninstalled via Manifests. Each Ingress Controller manages its own headless service.  NGINX Plus Required. | *False* |  |
+|*zone-sync-port* | Specifies the optional port on which NGINX Ingress Controller listens for zone sync traffic. NGINX Plus & `zone-sync` Required. | *12345* |  |
+|*zone-sync-resolver-addresses* | Configures optional addresses used in the [resolver](https://nginx.org/en/docs/http/ngx_http_core_module.html#resolver) directive for zone-sync. This field takes a comma separated list of addresses. NGINX Plus & `zone-sync` Required | `kube-dns.kube-system.svc.cluster.local` |  |
+|*zone-sync-resolver-ipv6* | Configures whether the optional [resolver](https://nginx.org/en/docs/http/ngx_http_core_module.html#resolver) directive for zone-sync will look up IPv6 addresses. NGINX Plus & `zone-sync` Required | `true` |  |
+|*zone-sync-resolver-valid* | Configures an [NGINX time](https://nginx.org/en/docs/syntax.html) that the optional [resolver](https://nginx.org/en/docs/http/ngx_http_core_module.html#resolver) directive for zone-sync will override the TTL value of responses from nameservers with. NGINX Plus & `zone-sync` Required | `5s` |  |
+{{</bootstrap-table>}}
+
+---
+
 ### Snippets and custom templates
 
 {{<bootstrap-table "table table-striped table-bordered table-responsive">}}

site/content/configuration/policy-resource.md

@@ -131,7 +131,7 @@ The feature is implemented using the NGINX [ngx_http_limit_req_module](https://n
 |``dryRun`` | Enables the dry run mode. In this mode, the rate limit is not actually applied, but the number of excessive requests is accounted as usual in the shared memory zone. | ``bool`` | No |
 |``logLevel`` | Sets the desired logging level for cases when the server refuses to process requests due to rate exceeding, or delays request processing. Allowed values are ``info``, ``notice``, ``warn`` or ``error``. Default is ``error``. | ``string`` | No |
 |``rejectCode`` | Sets the status code to return in response to rejected requests. Must fall into the range ``400..599``. Default is ``503``. | ``int`` | No |
-|``scale`` | Enables a constant rate-limit by dividing the configured rate by the number of nginx-ingress pods currently serving traffic. This adjustment ensures that the rate-limit remains consistent, even as the number of nginx-pods fluctuates due to autoscaling. Note: This will not work properly if requests from a client are not evenly distributed accross all ingress pods (sticky sessions, long lived TCP-Connections with many requests etc.). In such cases using NGINX+'s zone-sync feature instead would give better results. | ``bool`` | No |
+|``scale`` | Enables a constant rate-limit by dividing the configured rate by the number of nginx-ingress pods currently serving traffic. This adjustment ensures that the rate-limit remains consistent, even as the number of nginx-pods fluctuates due to autoscaling. **This will not work properly if requests from a client are not evenly distributed across all ingress pods** (Such as with sticky sessions, long lived TCP Connections with many requests, and so forth). In such cases using [zone-sync]({{< ref "/configuration/global-configuration/configmap-resource.md#zone-sync" >}}) instead would give better results. | ``bool`` | No |
 {{% /table %}}
 
 {{< note >}}