Add information on supported version skew and upgrade order

content/en/docs/reference/using-api/deprecation-policy.md

@@ -87,7 +87,7 @@ no less than:**
    * **Beta: 9 months or 3 releases (whichever is longer)**
    * **Alpha: 0 releases**
 
-This covers the maximum supported version skew of 2 releases.
+This covers the [maximum supported version skew of 2 releases](/docs/setup/version-skew-policy/).
 
 {{< note >}}
 Until [#52185](https://github.com/kubernetes/kubernetes/issues/52185) is

content/en/docs/setup/independent/create-cluster-kubeadm.md

@@ -589,8 +589,10 @@ Due to that we can't see into the future, kubeadm CLI vX.Y may or may not be abl
 Example: kubeadm v1.8 can deploy both v1.7 and v1.8 clusters and upgrade v1.7 kubeadm-created clusters to
 v1.8.
 
-Please also check our [installation guide](/docs/setup/independent/install-kubeadm/#installing-kubeadm-kubelet-and-kubectl)
-for more information on the version skew between kubelets and the control plane.
+These resources provide more information on supported version skew between kubelets and the control plane, and other Kubernetes components:
+
+* Kubernetes [version and version-skew policy](/docs/setup/version-skew-policy/)
+* Kubeadm-specific [installation guide](/docs/setup/independent/install-kubeadm/#installing-kubeadm-kubelet-and-kubectl)
 
 ## kubeadm works on multiple platforms {#multi-platform}
 

content/en/docs/setup/independent/install-kubeadm.md

@@ -119,8 +119,10 @@ This is because kubeadm and Kubernetes require
 [special attention to upgrade](/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade-1-11/).
 {{</ warning >}}
 
-For more information on version skews, please read our
-[version skew policy](/docs/setup/independent/create-cluster-kubeadm/#version-skew-policy).
+For more information on version skews, see:
+
+* Kubernetes [version and version-skew policy](/docs/setup/version-skew-policy/)
+* Kubeadm-specific [version skew policy](/docs/setup/independent/create-cluster-kubeadm/#version-skew-policy)
 
 {{< tabs name="k8s_install" >}}
 {{% tab name="Ubuntu, Debian or HypriotOS" %}}

content/en/docs/setup/version-skew-policy.md

@@ -0,0 +1,148 @@
+---
+reviewers:
+- sig-api-machinery
+- sig-architecture
+- sig-cli
+- sig-cluster-lifecycle
+- sig-node
+- sig-release
+title: Kubernetes Version and Version Skew Support Policy
+content_template: templates/concept
+weight: 70
+---
+
+{{% capture overview %}}
+This document describes the maximum version skew supported between various Kubernetes components.
+Specific cluster deployment tools may place additional restrictions on version skew.
+{{% /capture %}}
+
+{{% capture body %}}
+
+## Supported versions
+
+Kubernetes versions are expressed as **x.y.z**,
+where **x** is the major version, **y** is the minor version, and **z** is the patch version, following [Semantic Versioning](http://semver.org/) terminology.
+For more information, see [Kubernetes Release Versioning](https://github.com/kubernetes/community/blob/master/contributors/design-proposals/release/versioning.md#kubernetes-release-versioning).
+
+The Kubernetes project maintains release branches for the most recent three minor releases.
+
+Applicable fixes, including security fixes, may be backported to those three release branches, depending on severity and feasibility.
+Patch releases are cut from those branches at a regular cadence, or as needed.
+This decision is owned by the [patch release manager](https://github.com/kubernetes/sig-release/blob/master/release-team/role-handbooks/patch-release-manager/README.md#release-timing).
+The patch release manager is a member of the [release team for each release](https://github.com/kubernetes/sig-release/tree/master/releases/).
+
+Minor releases occur approximately every 3 months, so each minor release branch is maintained for approximately 9 months.
+
+## Supported version skew
+
+### kube-apiserver
+
+In [highly-availabile (HA) clusters](https://kubernetes.io/docs/setup/independent/high-availability/), the newest and oldest `kube-apiserver` instances must be within one minor version.
+
+Example:
+
+* newest `kube-apiserver` is at **1.13**
+* other `kube-apiserver` instances are supported at **1.13** and **1.12**
+
+### kubelet
+
+`kubelet` must not be newer than `kube-apiserver`, and may be up to two minor versions older.
+
+Example:
+
+* `kube-apiserver` is at **1.13**
+* `kubelet` is supported at **1.13**, **1.12**, and **1.11**
+
+{{< note >}}
+If version skew exists between `kube-apiserver` instances in an HA cluster, this narrows the allowed `kubelet` versions.
+{{</ note >}}
+
+Example:
+
+* `kube-apiserver` instances are at **1.13** and **1.12**
+* `kubelet` is supported at **1.12**, and **1.11** (**1.13** is not supported because that would be newer than the `kube-apiserver` instance at version **1.12**)
+
+### kube-controller-manager, kube-scheduler, and cloud-controller-manager
+
+`kube-controller-manager`, `kube-scheduler`, and `cloud-controller-manager` must not be newer than the `kube-apiserver` instances they communicate with. They are expected to match the `kube-apiserver` minor version, but may be up to one minor version older (to allow live upgrades).
+
+Example:
+
+* `kube-apiserver` is at **1.13**
+* `kube-controller-manager`, `kube-scheduler`, and `cloud-controller-manager` are supported at **1.13** and **1.12**
+
+{{< note >}}
+If version skew exists between `kube-apiserver` instances in an HA cluster, and these components can communicate with any `kube-apiserver` instance in the cluster (for example, via a load balancer), this narrows the allowed versions of these components.
+{{< /note >}}
+
+Example:
+
+* `kube-apiserver` instances are at **1.13** and **1.12**
+* `kube-controller-manager`, `kube-scheduler`, and `cloud-controller-manager` communicate with a load balancer that can route to any `kube-apiserver` instance
+* `kube-controller-manager`, `kube-scheduler`, and `cloud-controller-manager` are supported at **1.12** (**1.13** is not supported because that would be newer than the `kube-apiserver` instance at version **1.12**)
+
+### kubectl
+
+`kubectl` is supported within one minor version (older or newer) of `kube-apiserver`.
+
+Example:
+
+* `kube-apiserver` is at **1.13**
+* `kubectl` is supported at **1.14**, **1.13**, and **1.12**
+
+{{< note >}}
+If version skew exists between `kube-apiserver` instances in an HA cluster, this narrows the supported `kubectl` versions.
+{{< /note >}}
+
+Example:
+
+* `kube-apiserver` instances are at **1.13** and **1.12**
+* `kubectl` is supported at **1.13** and **1.12** (other versions would be more than one minor version skewed from one of the `kube-apiserver` components)
+
+## Supported component upgrade order
+
+The supported version skew between components has implications on the order in which components must be upgraded.
+This section describes the order in which components must be upgraded to transition an existing cluster from version **1.n** to version **1.(n+1)**.
+
+### kube-apiserver
+
+Pre-requisites:
+
+* In a single-instance cluster, the existing `kube-apiserver` instance is **1.n**
+* In an HA cluster, all `kube-apiserver` instances are at **1.n** or **1.(n+1)** (this ensures maximum skew of 1 minor version between the oldest and newest `kube-apiserver` instance)
+* The `kube-controller-manager`, `kube-scheduler`, and `cloud-controller-manager` instances that communicate with this server are at version **1.n** (this ensures they are not newer than the existing API server version, and are within 1 minor version of the new API server version)
+* `kubelet` instances on all nodes are at version **1.n** or **1.(n-1)** (this ensures they are not newer than the existing API server version, and are within 2 minor versions of the new API server version)
+* Registered admission webhooks are able to handle the data the new `kube-apiserver` instance will send them:
+  * `ValidatingWebhookConfiguration` and `MutatingWebhookConfiguration` objects are updated to include any new versions of REST resources added in **1.(n+1)**
+  * The webhooks are able to handle any new versions of REST resources that will be sent to them, and any new fields added to existing versions in **1.(n+1)**
+
+Upgrade `kube-apiserver` to **1.(n+1)**
+
+{{< note >}}
+Project policies for [API deprecation](https://kubernetes.io/docs/reference/using-api/deprecation-policy/) and 
+[API change guidelines](https://github.com/kubernetes/community/blob/master/contributors/devel/api_changes.md) 
+require `kube-apiserver` to not skip minor versions when upgrading, even in single-instance clusters.
+{{< /note >}}
+
+### kube-controller-manager, kube-scheduler, and cloud-controller-manager
+
+Pre-requisites:
+
+* The `kube-apiserver` instances these components communicate with are at **1.(n+1)** (in HA clusters in which these control plane components can communicate with any `kube-apiserver` instance in the cluster, all `kube-apiserver` instances must be upgraded before upgrading these components)
+
+Upgrade `kube-controller-manager`, `kube-scheduler`, and `cloud-controller-manager` to **1.(n+1)**
+
+### kubelet
+
+Pre-requisites:
+
+* The `kube-apiserver` instances the `kubelet` communicates with are at **1.(n+1)**
+
+Optionally upgrade `kubelet` instances to **1.(n+1)** (or they can be left at **1.n** or **1.(n-1)**)
+
+{{< warning >}}
+Running a cluster with `kubelet` instances that are persistently two minor versions behind `kube-apiserver` is not recommended:
+
+* they must be upgraded within one minor version of `kube-apiserver` before the control plane can be upgraded
+* it increases the likelihood of running `kubelet` versions older than the three maintained minor releases
+{{</ warning >}}

content/en/docs/user-journeys/users/cluster-operator/foundational.md

@@ -65,7 +65,8 @@ These resources are covered in a number of articles within the Kubernetes docume
 
 As a cluster operator you may not need to use all these resources, although you should be familiar with them to understand how the cluster is being used.
 There are a number of additional resources that you should be aware of, some listed under [Intermediate Resources](/docs/user-journeys/users/cluster-operator/intermediate#section-1).
-You should also be familiar with [how to manage kubernetes resources](/docs/concepts/cluster-administration/manage-deployment/).
+You should also be familiar with [how to manage kubernetes resources](/docs/concepts/cluster-administration/manage-deployment/)
+and [supported versions and version skew between cluster components](/docs/setup/version-skew-policy/).
 
 ## Get information about your cluster
 

data/setup.yml

@@ -135,3 +135,5 @@ toc:
 
 - title: Building High-Availability Clusters
   path: /docs/admin/high-availability/building/
+
+- docs/setup/version-skew-policy.md