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Clean up /kubeadm/install-kubeadm.md
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@windsonsea @Community-Programmer
windsonsea authored and Community-Programmer committed Oct 13, 2023
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Expand Up @@ -15,10 +15,8 @@ This page shows how to install the `kubeadm` toolbox.
For information on how to create a cluster with kubeadm once you have performed this installation process,
see the [Creating a cluster with kubeadm](/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/) page.


## {{% heading "prerequisites" %}}


* 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).
Expand Down Expand Up @@ -59,6 +57,7 @@ If you have more than one network adapter, and your Kubernetes components are no
route, we recommend you add IP route(s) so Kubernetes cluster addresses go via the appropriate adapter.

## Check required ports

These [required ports](/docs/reference/networking/ports-and-protocols/)
need to be open in order for Kubernetes components to communicate with each other.
You can use tools like netcat to check if a port is open. For example:
Expand Down Expand Up @@ -131,7 +130,7 @@ You will install these packages on all of your machines:
* `kubeadm`: the command to bootstrap the cluster.

* `kubelet`: the component that runs on all of the machines in your cluster
and does things like starting pods and containers.
and does things like starting pods and containers.

* `kubectl`: the command line util to talk to your cluster.

Expand Down Expand Up @@ -159,7 +158,7 @@ For more information on version skews, see:
{{< note >}}
Kubernetes has [new package repositories hosted at `pkgs.k8s.io`](/blog/2023/08/15/pkgs-k8s-io-introduction/)
starting from August 2023. The legacy package repositories (`apt.kubernetes.io` and `yum.kubernetes.io`)
have been frozen starting from September 13, 2023. Please read our
have been frozen starting from September 13, 2023. Please read our
[deprecation and freezing announcement](/blog/2023/08/31/legacy-package-repository-deprecation/)
for more details.
{{< /note >}}
Expand All @@ -177,7 +176,8 @@ These instructions are for Kubernetes {{< skew currentVersion >}}.
sudo apt-get install -y apt-transport-https ca-certificates curl
```

2. Download the public signing key for the Kubernetes package repositories. The same signing key is used for all repositories so you can disregard the version in the URL:
2. Download the public signing key for the Kubernetes package repositories.
The same signing key is used for all repositories so you can disregard the version in the URL:

```shell
curl -fsSL https://pkgs.k8s.io/core:/stable:/{{< param "version" >}}/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
Expand Down Expand Up @@ -208,47 +208,47 @@ you can create it by running `sudo mkdir -m 755 /etc/apt/keyrings`

1. Set SELinux to `permissive` mode:

These instructions are for Kubernetes {{< skew currentVersion >}}.
These instructions are for Kubernetes {{< skew currentVersion >}}.

```shell
# Set SELinux in permissive mode (effectively disabling it)
sudo setenforce 0
sudo sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config
```
```shell
# Set SELinux in permissive mode (effectively disabling it)
sudo setenforce 0
sudo sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config
```

{{< caution >}}
- Setting SELinux in permissive mode by running `setenforce 0` and `sed ...`
effectively disables it. This is required to allow containers to access the host
filesystem; for example, some cluster network plugins require that. You have to
do this until SELinux support is improved in the kubelet.
- You can leave SELinux enabled if you know how to configure it but it may require
settings that are not supported by kubeadm.
{{< /caution >}}
{{< caution >}}
- Setting SELinux in permissive mode by running `setenforce 0` and `sed ...`
effectively disables it. This is required to allow containers to access the host
filesystem; for example, some cluster network plugins require that. You have to
do this until SELinux support is improved in the kubelet.
- You can leave SELinux enabled if you know how to configure it but it may require
settings that are not supported by kubeadm.
{{< /caution >}}

2. Add the Kubernetes `yum` repository. The `exclude` parameter in the
repository definition ensures that the packages related to Kubernetes are
not upgraded upon running `yum update` as there's a special procedure that
must be followed for upgrading Kubernetes.

```shell
# This overwrites any existing configuration in /etc/yum.repos.d/kubernetes.repo
cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://pkgs.k8s.io/core:/stable:/{{< param "version" >}}/rpm/
enabled=1
gpgcheck=1
gpgkey=https://pkgs.k8s.io/core:/stable:/{{< param "version" >}}/rpm/repodata/repomd.xml.key
exclude=kubelet kubeadm kubectl cri-tools kubernetes-cni
EOF
```
```shell
# This overwrites any existing configuration in /etc/yum.repos.d/kubernetes.repo
cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://pkgs.k8s.io/core:/stable:/{{< param "version" >}}/rpm/
enabled=1
gpgcheck=1
gpgkey=https://pkgs.k8s.io/core:/stable:/{{< param "version" >}}/rpm/repodata/repomd.xml.key
exclude=kubelet kubeadm kubectl cri-tools kubernetes-cni
EOF
```
3. Install kubelet, kubeadm and kubectl, and enable kubelet to ensure it's automatically started on startup:
```shell
sudo yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes
sudo systemctl enable --now kubelet
```
```shell
sudo yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes
sudo systemctl enable --now kubelet
```
{{% /tab %}}
{{% tab name="Without a package manager" %}}
Expand All @@ -262,7 +262,7 @@ sudo mkdir -p "$DEST"
curl -L "https://github.com/containernetworking/plugins/releases/download/${CNI_PLUGINS_VERSION}/cni-plugins-linux-${ARCH}-${CNI_PLUGINS_VERSION}.tgz" | sudo tar -C "$DEST" -xz
```
Define the directory to download command files
Define the directory to download command files:
{{< note >}}
The `DOWNLOAD_DIR` variable must be set to a writable directory.
Expand All @@ -274,7 +274,7 @@ DOWNLOAD_DIR="/usr/local/bin"
sudo mkdir -p "$DOWNLOAD_DIR"
```
Install crictl (required for kubeadm / Kubelet Container Runtime Interface (CRI))
Install crictl (required for kubeadm / Kubelet Container Runtime Interface (CRI)):
```bash
CRICTL_VERSION="v1.28.0"
Expand All @@ -298,7 +298,8 @@ curl -sSL "https://raw.githubusercontent.com/kubernetes/release/${RELEASE_VERSIO
```
{{< note >}}
Please refer to the note in the [Before you begin](#before-you-begin) section for Linux distributions that do not include `glibc` by default.
Please refer to the note in the [Before you begin](#before-you-begin) section for Linux distributions
that do not include `glibc` by default.
{{< /note >}}
Install `kubectl` by following the instructions on [Install Tools page](/docs/tasks/tools/#kubectl).
Expand All @@ -312,12 +313,12 @@ systemctl enable --now kubelet
{{< note >}}
The Flatcar Container Linux distribution mounts the `/usr` directory as a read-only filesystem.
Before bootstrapping your cluster, you need to take additional steps to configure a writable directory.
See the [Kubeadm Troubleshooting guide](/docs/setup/production-environment/tools/kubeadm/troubleshooting-kubeadm/#usr-mounted-read-only/) to learn how to set up a writable directory.
See the [Kubeadm Troubleshooting guide](/docs/setup/production-environment/tools/kubeadm/troubleshooting-kubeadm/#usr-mounted-read-only/)
to learn how to set up a writable directory.
{{< /note >}}
{{% /tab %}}
{{< /tabs >}}

The kubelet is now restarting every few seconds, as it waits in a crashloop for
kubeadm to tell it what to do.
Expand All @@ -335,7 +336,8 @@ See [Configuring a cgroup driver](/docs/tasks/administer-cluster/kubeadm/configu
## Troubleshooting
If you are running into difficulties with kubeadm, please consult our [troubleshooting docs](/docs/setup/production-environment/tools/kubeadm/troubleshooting-kubeadm/).
If you are running into difficulties with kubeadm, please consult our
[troubleshooting docs](/docs/setup/production-environment/tools/kubeadm/troubleshooting-kubeadm/).
## {{% heading "whatsnext" %}}
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