kubeadm: add task pages for adding Linux and Windows worker nodes

Adjust the "create a kubeadm cluster" page to link to
two separate task pages for adding Linux / Windows worker nodes.

Base the Windows page on the existing document:
https://github.com/kubernetes-sigs/sig-windows-tools/blob/master/guides/guide-for-adding-windows-node.md

content/en/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm.md

@@ -166,8 +166,9 @@ The control-plane node is the machine where the control plane components run, in
 communicates with).
 
 1. (Recommended) If you have plans to upgrade this single control-plane `kubeadm` cluster
-to high availability you should specify the `--control-plane-endpoint` to set the shared endpoint
-for all control-plane nodes. Such an endpoint can be either a DNS name or an IP address of a load-balancer.
+to [high availability](/docs/setup/production-environment/tools/kubeadm/high-availability/)
+you should specify the `--control-plane-endpoint` to set the shared endpoint for all control-plane nodes.
+Such an endpoint can be either a DNS name or an IP address of a load-balancer.
 1. Choose a Pod network add-on, and verify whether it requires any arguments to
 be passed to `kubeadm init`. Depending on which
 third-party provider you choose, you might need to set the `--pod-network-cidr` to
@@ -343,6 +344,11 @@ control-plane node or a node that has the kubeconfig credentials:
 kubectl apply -f <add-on.yaml>
 ```
 
+{{< note >}}
+Only a few CNI plugins support Windows. More details and setup instructions can be found
+in [Adding Windows worker nodes](/docs/tasks/administer-cluster/kubeadm/adding-windows-nodes/#network-config).
+{{< /note >}}
+
 You can install only one Pod network per cluster.
 
 Once a Pod network has been installed, you can confirm that it is working by
@@ -391,90 +397,20 @@ from the control plane node, which excludes it from the list of backend servers:
 kubectl label nodes --all node.kubernetes.io/exclude-from-external-load-balancers-
 ```
 
-### Joining your nodes {#join-nodes}
-
-The nodes are where your workloads (containers and Pods, etc) run. To add new nodes to your cluster do the following for each machine:
-
-* SSH to the machine
-* Become root (e.g. `sudo su -`)
-* [Install a runtime](/docs/setup/production-environment/tools/kubeadm/install-kubeadm/#installing-runtime)
-  if needed
-* Run the command that was output by `kubeadm init`. For example:
-
-  ```bash
-  kubeadm join --token <token> <control-plane-host>:<control-plane-port> --discovery-token-ca-cert-hash sha256:<hash>
-  ```
-
-If you do not have the token, you can get it by running the following command on the control-plane node:
-
-```bash
-kubeadm token list
-```
-
-The output is similar to this:
-
-```console
-TOKEN                    TTL  EXPIRES              USAGES           DESCRIPTION            EXTRA GROUPS
-8ewj1p.9r9hcjoqgajrj4gi  23h  2018-06-12T02:51:28Z authentication,  The default bootstrap  system:
-                                                   signing          token generated by     bootstrappers:
-                                                                    'kubeadm init'.        kubeadm:
-                                                                                           default-node-token
-```
-
-By default, tokens expire after 24 hours. If you are joining a node to the cluster after the current token has expired,
-you can create a new token by running the following command on the control-plane node:
-
-```bash
-kubeadm token create
-```
-
-The output is similar to this:
+### Adding more control plane nodes
 
-```console
-5didvk.d09sbcov8ph2amjw
-```
-
-If you don't have the value of `--discovery-token-ca-cert-hash`, you can get it by running the
-following command chain on the control-plane node:
-
-```bash
-openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | \
-   openssl dgst -sha256 -hex | sed 's/^.* //'
-```
-
-The output is similar to:
-
-```console
-8cb2de97839780a412b93877f8507ad6c94f73add17d5d7058e91741c9d5ec78
-```
-
-{{< note >}}
-To specify an IPv6 tuple for `<control-plane-host>:<control-plane-port>`, IPv6 address must be enclosed in square brackets, for example: `[2001:db8::101]:2073`.
-{{< /note >}}
+See [Creating Highly Available Clusters with kubeadm](/docs/setup/production-environment/tools/kubeadm/high-availability/) for steps on creating a high availability kubeadm cluster by adding more control plane
+nodes.
 
-The output should look something like:
+### Adding worker nodes {#join-nodes}
 
-```
-[preflight] Running pre-flight checks
+The worker nodes are where your workloads run.
 
-... (log output of join workflow) ...
+The following pages show how to add Linux and Windows worker nodes to the cluster by using
+the `kubeadm join` command:
 
-Node join complete:
-* Certificate signing request sent to control-plane and response
-  received.
-* Kubelet informed of new secure connection details.
-
-Run 'kubectl get nodes' on control-plane to see this machine join.
-```
-
-A few seconds later, you should notice this node in the output from `kubectl get
-nodes` when run on the control-plane node.
-
-{{< note >}}
-As the cluster nodes are usually initialized sequentially, the CoreDNS Pods are likely to all run
-on the first control-plane node. To provide higher availability, please rebalance the CoreDNS Pods
-with `kubectl -n kube-system rollout restart deployment coredns` after at least one new node is joined.
-{{< /note >}}
+* [Adding Linux worker nodes](/docs/tasks/administer-cluster/kubeadm/adding-linux-nodes/)
+* [Adding Windows worker nodes](/docs/tasks/administer-cluster/kubeadm/adding-windows-nodes/)
 
 ### (Optional) Controlling your cluster from machines other than the control-plane node
 

content/en/docs/setup/production-environment/tools/kubeadm/install-kubeadm.md

@@ -22,7 +22,7 @@ see the [Creating a cluster with kubeadm](/docs/setup/production-environment/too
 * A compatible Linux host. The Kubernetes project provides generic instructions for Linux distributions
   based on Debian and Red Hat, and those distributions without a package manager.
 * 2 GB or more of RAM per machine (any less will leave little room for your apps).
-* 2 CPUs or more.
+* 2 CPUs or more for control plane machines.
 * Full network connectivity between all machines in the cluster (public or private network is fine).
 * Unique hostname, MAC address, and product_uuid for every node. See [here](#verify-mac-address) for more details.
 * Certain ports are open on your machines. See [here](#check-required-ports) for more details.

content/en/docs/tasks/administer-cluster/kubeadm/adding-linux-nodes.md

@@ -0,0 +1,109 @@
+---
+title: Adding Linux worker nodes
+content_type: task
+weight: 50
+---
+
+<!-- overview -->
+
+This page explains how to add Linux worker nodes to a kubeadm cluster.
+
+## {{% heading "prerequisites" %}}
+
+* Each joining worker node has installed the required components from
+[Installing kubeadm](/docs/setup/production-environment/tools/kubeadm/install-kubeadm/), such as,
+kubeadm, the kubelet and a {{< glossary_tooltip term_id="container-runtime" text="container runtime" >}}.
+* A running kubeadm cluster created by `kubeadm init` and following the steps
+in the document [Creating a cluster with kubeadm](/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/).
+* You need superuser access to the node.
+
+<!-- steps -->
+
+## Adding Linux worker nodes
+
+To add new Linux worker nodes to your cluster do the following for each machine:
+
+1. Connect to the machine by using SSH or another method.
+1. Run the command that was output by `kubeadm init`. For example:
+
+  ```bash
+  sudo kubeadm join --token <token> <control-plane-host>:<control-plane-port> --discovery-token-ca-cert-hash sha256:<hash>
+  ```
+
+### Additional information for kubeadm join
+
+{{< note >}}
+To specify an IPv6 tuple for `<control-plane-host>:<control-plane-port>`, IPv6 address must be enclosed in square brackets, for example: `[2001:db8::101]:2073`.
+{{< /note >}}
+
+If you do not have the token, you can get it by running the following command on the control plane node:
+
+```bash
+sudo kubeadm token list
+```
+
+The output is similar to this:
+
+```console
+TOKEN                    TTL  EXPIRES              USAGES           DESCRIPTION            EXTRA GROUPS
+8ewj1p.9r9hcjoqgajrj4gi  23h  2018-06-12T02:51:28Z authentication,  The default bootstrap  system:
+                                                   signing          token generated by     bootstrappers:
+                                                                    'kubeadm init'.        kubeadm:
+                                                                                           default-node-token
+```
+
+By default, node join tokens expire after 24 hours. If you are joining a node to the cluster after the
+current token has expired, you can create a new token by running the following command on the
+control plane node:
+
+```bash
+sudo kubeadm token create
+```
+
+The output is similar to this:
+
+```console
+5didvk.d09sbcov8ph2amjw
+```
+
+If you don't have the value of `--discovery-token-ca-cert-hash`, you can get it by running the
+following commands on the control plane node:
+
+```bash
+sudo cat /etc/kubernetes/pki/ca.crt | openssl x509 -pubkey  | openssl rsa -pubin -outform der 2>/dev/null | \
+   openssl dgst -sha256 -hex | sed 's/^.* //'
+```
+
+The output is similar to:
+
+```console
+8cb2de97839780a412b93877f8507ad6c94f73add17d5d7058e91741c9d5ec78
+```
+
+The output of the `kubeadm join` command should look something like:
+
+```
+[preflight] Running pre-flight checks
+
+... (log output of join workflow) ...
+
+Node join complete:
+* Certificate signing request sent to control-plane and response
+  received.
+* Kubelet informed of new secure connection details.
+
+Run 'kubectl get nodes' on control-plane to see this machine join.
+```
+
+A few seconds later, you should notice this node in the output from `kubectl get nodes`.
+(for example, run `kubectl` on a  control plane node).
+
+{{< note >}}
+As the cluster nodes are usually initialized sequentially, the CoreDNS Pods are likely to all run
+on the first control plane node. To provide higher availability, please rebalance the CoreDNS Pods
+with `kubectl -n kube-system rollout restart deployment coredns` after at least one new node is joined.
+{{< /note >}}
+
+## {{% heading "whatsnext" %}}
+
+* See how to [add Windows worker nodes](/docs/tasks/administer-cluster/kubeadm/adding-windows-nodes/).