[Docs][KubeRay] Add doc for kubectl plugin

doc/source/cluster/kubernetes/user-guides.md

@@ -25,6 +25,7 @@ user-guides/helm-chart-rbac
 user-guides/tls
 user-guides/k8s-autoscaler
 user-guides/static-ray-cluster-without-kuberay
+user-guides/kubectl-plugin
 ```
 
 
@@ -53,3 +54,4 @@ at the {ref}`introductory guide <kuberay-quickstart>` first.
 * {ref}`kuberay-gke-bucket`
 * {ref}`ray-k8s-autoscaler-comparison`
 * {ref}`deploy-a-static-ray-cluster-without-kuberay`
+* {ref}`kubectl-plugin`

doc/source/cluster/kubernetes/user-guides/kubectl-plugin.md

@@ -0,0 +1,89 @@
+(kubectl-plugin)=
+
+# Use Kubectl Plugin (Alpha Feature)
+
+Starting from KubeRay v1.2.2, we have introduced a `kubectl ray` plugin to simplify common workflows when deploying Ray on Kubernetes. The plugin is designed to help users who are not familiar with Kubernetes to run Ray on Kubernetes with ease.
+
+## Installation
+
+Please follow the instructions in the [KubeRay Kubectl Plugin](https://github.com/ray-project/kuberay/tree/master/kubectl-plugin) to install the plugin.
+
+Currently, the recommended way to install the plugin is to download the binary from the [release page](https://github.com/ray-project/kuberay/releases) and add it to your PATH.
+
+For example, to install plugin version 1.2.2 on Linux amd64:
+
+```shell
+curl -LO https://github.com/ray-project/kuberay/releases/download/v1.2.2/kubectl-ray_v1.2.2_linux_amd64.tar.gz
+tar -xvf kubectl-ray_v1.2.2_linux_amd64.tar.gz
+cp kubectl-ray ~/.local/bin
+```
+
+Replace `~/.local/bin` with the directory in your `PATH`.
+
+## Usage
+
+After installing the plugin, you can use `kubectl ray --help` to see the available commands and options.
+
+## Example
+
+Here assume you have a Ray cluster running on Kubernetes. Please see {ref}`RayCluster Quickstart <kuberay-raycluster-quickstart>` if you don't have a Ray cluster running on Kubernetes.
+
+### Get all Ray clusters
+
+```shell
+$ kubectl ray cluster get
+
+NAME                  NAMESPACE   DESIRED WORKERS   AVAILABLE WORKERS   CPUS   GPUS   TPUS   MEMORY   AGE
+ray-cluster-kuberay   default     1                                     2      0      0      3G       24s
+```
+
+### Forward local ports to Ray cluster
+
+```shell
+$ kubectl ray session ray-cluster-kuberay
+
+Forwarding ports to service ray-cluster-kuberay-head-svc
+Ray Dashboard: http://localhost:8265
+Ray Interactive Client: http://localhost:10001
+
+Forwarding from 127.0.0.1:8265 -> 8265
+Forwarding from [::1]:8265 -> 8265
+Forwarding from 127.0.0.1:10001 -> 10001
+Forwarding from [::1]:10001 -> 10001
+```
+
+### Get Ray cluster logs
+
+```shell
+$ kubectl ray log ray-cluster-kuberay
+
+No output directory specified, creating dir under current directory using cluster name.
+Downloading file ./ for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./old/ for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./gcs_server.out for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./gcs_server.err for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./events/ for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./events/event_GCS.log for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./events/event_AUTOSCALER.log for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./events/event_RAYLET.log for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./debug_state_gcs.txt for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./monitor.out for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./monitor.err for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./ray_client_server.out for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./ray_client_server.err for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./dashboard.err for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./dashboard.log for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./monitor.log for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./raylet.out for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./raylet.err for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./log_monitor.err for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./debug_state.txt for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./log_monitor.log for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./dashboard_agent.log for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./agent-424238335.out for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./agent-424238335.err for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./runtime_env_agent.out for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./runtime_env_agent.err for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./runtime_env_agent.log for Ray Head ray-cluster-kuberay-head-qkrv8
+Downloading file ./nsight/ for Ray Head ray-cluster-kuberay-head-qkrv8
+```