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[install-kubeadm]: Update instructions to disable or tolerate swap #47710

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Sep 3, 2024
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[install-kubeadm]: Update instructions to disable or tolerate swap #47710

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42dd7e5
minor gramattical fixes
iholder101 Aug 28, 2024
3b95b00
Update instructions to disable or tolerate swap
iholder101 Aug 28, 2024
3b09c30
Move swap into a its own header
iholder101 Aug 29, 2024
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20 changes: 15 additions & 5 deletions content/en/docs/setup/production-environment/tools/kubeadm/install-kubeadm.md
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Expand Up @@ -26,11 +26,6 @@ see the [Creating a cluster with kubeadm](/docs/setup/production-environment/too
* 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.
* Swap configuration. The default behavior of a kubelet was to fail to start if swap memory was detected on a node.
See [Swap memory management](/docs/concepts/architecture/nodes/#swap-memory) for more details.
* You **MUST** disable swap if the kubelet is not properly configured to use swap. For example, `sudo swapoff -a`
will disable swapping temporarily. To make this change persistent across reboots, make sure swap is disabled in
config files like `/etc/fstab`, `systemd.swap`, depending how it was configured on your system.

{{< note >}}
The `kubeadm` installation is done via binaries that use dynamic linking and assumes that your target system provides `glibc`.
Expand Down Expand Up @@ -71,6 +66,21 @@ The pod network plugin you use may also require certain ports to be
open. Since this differs with each pod network plugin, please see the
documentation for the plugins about what port(s) those need.

## Swap configuration {#swap-configuration}

The default behavior of a kubelet is to fail to start if swap memory is detected on a node.
This means that swap should either be disabled or tolerated by kubelet.

* To tolerate swap, add `failSwapOn: false` to kubelet configuration or as a command line argument.
Note: even if `failSwapOn: false` is provided, workloads wouldn't have swap access by default.
This can be changed by setting a `swapBehavior`, again in the kubelet configuration file. To use swap,
set a `swapBehavior` other than the default `NoSwap` setting.
See [Swap memory management](/docs/concepts/architecture/nodes/#swap-memory) for more details.
* To disable swap, `sudo swapoff -a` can be used to disable swapping temporarily.
To make this change persistent across reboots, make sure swap is disabled in
config files like `/etc/fstab`, `systemd.swap`, depending how it was configured on your system.


## Installing a container runtime {#installing-runtime}

To run containers in Pods, Kubernetes uses a
Expand Down