k3s/examples/flexvolume/README.md

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<h2>PLEASE NOTE: This document applies to the HEAD of the source tree</h2>

If you are using a released version of Kubernetes, you should
refer to the docs that go with that version.

Documentation for other releases can be found at
[releases.k8s.io](http://releases.k8s.io).
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# Flexvolume

Flexvolume enables users to mount vendor volumes into kubernetes. It expects vendor drivers are installed in the volume plugin path on every kubelet node.

It allows for vendors to develop their own drivers to mount volumes on nodes.

*Note: Flexvolume is an alpha feature and is most likely to change in future*

## Prerequisites

Install the vendor driver on all nodes in the kubelet plugin path. Path for installing the plugin: /usr/libexec/kubernetes/kubelet-plugins/volume/exec/\<vendor~driver\>/\<driver\>

For example to add a 'cifs' driver, by vendor 'foo' install the driver at: /usr/libexec/kubernetes/kubelet-plugins/volume/exec/\<foo~cifs\>/cifs

## Plugin details

Driver will be invoked with 'Init' to initialize the driver. It will be invoked with 'attach' to attach the volume and with 'detach' to detach the volume from the kubelet node. It also supports custom mounts using 'mount' and 'unmount' callouts to the driver.

### Driver invocation model:

Init:
\<driver executable\> init

Attach:
\<driver executable\> attach \<json options\>

Detach:
\<driver executable\> detach \<mount device\>

Mount:
\<driver executable\> mount \<target mount dir\> \<mount device\> \<json options\>

Unmount:
\<driver executable\> unmount \<mount dir\>

See lvm[lvm] for a quick example on how to write a simple flexvolume driver.

### Example of Flexvolume

See nginx.yaml[nginx.yaml] for a quick example on how to use Flexvolume in a pod.

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