Merge pull request #24909 from zshihang/token

 separate RootCAConfigMap from BoundServiceAccountToken and Beta

content/en/docs/reference/access-authn-authz/service-accounts-admin.md

@@ -10,7 +10,7 @@ weight: 50
 ---
 
 <!-- overview -->
-This is a Cluster Administrator guide to service accounts. You should be familiar with 
+This is a Cluster Administrator guide to service accounts. You should be familiar with
 [configuring Kubernetes service accounts](/docs/tasks/configure-pod-container/configure-service-account/).
 
 Support for authorization and user accounts is planned but incomplete.  Sometimes
@@ -59,9 +59,13 @@ It acts synchronously to modify pods as they are created or updated. When this p
   1. It adds a `volume` to the pod which contains a token for API access.
   1. It adds a `volumeSource` to each container of the pod mounted at `/var/run/secrets/kubernetes.io/serviceaccount`.
 
-Starting from v1.13, you can migrate a service account volume to a projected volume when
-the `BoundServiceAccountTokenVolume` feature gate is enabled.
-The service account token will expire after 1 hour or the pod is deleted. See more details about [projected volume](/docs/tasks/configure-pod-container/configure-projected-volume-storage/).
+#### Bound Service Account Token Volume
+{{< feature-state for_k8s_version="v1.13" state="alpha" >}}
+
+When the `BoundServiceAccountTokenVolume` feature gate is enabled, the service account admission controller will
+add a projected service account token volume instead of a secret volume. The service account token will expire after 1 hour by default or the pod is deleted. See more details about [projected volume](/docs/tasks/configure-pod-container/configure-projected-volume-storage/).
+
+This feature depends on the `RootCAConfigMap` feature gate enabled which publish a "kube-root-ca.crt" ConfigMap to every namespace. This ConfigMap contains a CA bundle used for verifying connections to the kube-apiserver.
 
 ### Token Controller
 
@@ -115,4 +119,3 @@ kubectl delete secret mysecretname
 
 Service Account Controller manages ServiceAccount inside namespaces, and ensures
 a ServiceAccount named "default" exists in every active namespace.
-

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

@@ -131,6 +131,8 @@ different Kubernetes components.
 | `ProcMountType` | `false` | Alpha | 1.12 | |
 | `QOSReserved` | `false` | Alpha | 1.11 | |
 | `RemainingItemCount` | `false` | Alpha | 1.15 | |
+| `RootCAConfigMap` | `false` | Alpha | 1.13 | 1.19 |
+| `RootCAConfigMap` | `true` | Beta | 1.20 | |
 | `RotateKubeletServerCertificate` | `false` | Alpha | 1.7 | 1.11 |
 | `RotateKubeletServerCertificate` | `true` | Beta | 1.12 | |
 | `RunAsGroup` | `true` | Beta | 1.14 | |
@@ -513,6 +515,8 @@ Each feature gate is designed for enabling/disabling a specific feature:
   the input Pod's cpu and memory limits. The intent is to break ties between
   nodes with same scores.
 - `ResourceQuotaScopeSelectors`: Enable resource quota scope selectors.
+- `RootCAConfigMap`: Configure the kube-controller-manager to publish a {{< glossary_tooltip text="ConfigMap" term_id="configmap" >}} named `kube-root-ca.crt` to every namespace. This ConfigMap contains a CA bundle used for verifying connections to the kube-apiserver.
+   See [Bound Service Account Tokens](https://github.com/kubernetes/enhancements/blob/master/keps/sig-auth/1205-bound-service-account-tokens/README.md) for more details.
 - `RotateKubeletClientCertificate`: Enable the rotation of the client TLS certificate on the kubelet.
   See [kubelet configuration](/docs/reference/command-line-tools-reference/kubelet-tls-bootstrapping/#kubelet-configuration) for more details.
 - `RotateKubeletServerCertificate`: Enable the rotation of the server TLS certificate on the kubelet.