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kubeadm: add task pages for adding Linux and Windows worker nodes
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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
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@neolit123
neolit123 committed Sep 12, 2024
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98 changes: 17 additions & 81 deletions ...nt/en/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm.md
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Expand Up @@ -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
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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

Expand Down
2 changes: 1 addition & 1 deletion content/en/docs/setup/production-environment/tools/kubeadm/install-kubeadm.md
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Expand Up @@ -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.
Expand Down
109 changes: 109 additions & 0 deletions content/en/docs/tasks/administer-cluster/kubeadm/adding-linux-nodes.md
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@@ -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/).
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