c12s-kubespray/docs/kubernetes-apps/local_volume_provisioner.md
Olivier Lemasle 5d1fe64bc8
Update local-volume-provisioner (#9463)
- Update and re-work the documentation:
  - Update links
  - Fix formatting (especially for lists)
  - Remove documentation about `useAlphaApi`,
    a flag only for k8s versions < v1.10
  - Attempt to clarify the doc
- Update to version 1.5.0
- Remove PodSecurityPolicy (deprecated in k8s v1.21+)
- Update ClusterRole following upstream
  (cf https://github.com/kubernetes-sigs/sig-storage-local-static-provisioner/pull/292)
- Add nodeSelector to DaemonSet (following upstream)
2022-11-07 15:28:17 -08:00

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# Local Static Storage Provisioner
The [local static storage provisioner](https://github.com/kubernetes-sigs/sig-storage-local-static-provisioner)
is NOT a dynamic storage provisioner as you would
expect from a cloud provider. Instead, it simply creates PersistentVolumes for
all mounts under the `host_dir` of the specified storage class.
These storage classes are specified in the `local_volume_provisioner_storage_classes` nested dictionary.
Example:
```yaml
local_volume_provisioner_storage_classes:
local-storage:
host_dir: /mnt/disks
mount_dir: /mnt/disks
fast-disks:
host_dir: /mnt/fast-disks
mount_dir: /mnt/fast-disks
block_cleaner_command:
- "/scripts/shred.sh"
- "2"
volume_mode: Filesystem
fs_type: ext4
```
For each key in `local_volume_provisioner_storage_classes` a "storage class" with
the same name is created in the entry `storageClassMap` of the ConfigMap `local-volume-provisioner`.
The subkeys of each storage class in `local_volume_provisioner_storage_classes`
are converted to camelCase and added as attributes to the storage class in the
ConfigMap.
The result of the above example is:
```yaml
data:
storageClassMap: |
local-storage:
hostDir: /mnt/disks
mountDir: /mnt/disks
fast-disks:
hostDir: /mnt/fast-disks
mountDir: /mnt/fast-disks
blockCleanerCommand:
- "/scripts/shred.sh"
- "2"
volumeMode: Filesystem
fsType: ext4
```
Additionally, a StorageClass object (`storageclasses.storage.k8s.io`) is also
created for each storage class:
```bash
$ kubectl get storageclasses.storage.k8s.io
NAME PROVISIONER RECLAIMPOLICY
fast-disks kubernetes.io/no-provisioner Delete
local-storage kubernetes.io/no-provisioner Delete
```
The default StorageClass is `local-storage` on `/mnt/disks`;
the rest of this documentation will use that path as an example.
## Examples to create local storage volumes
1. Using tmpfs
```bash
for vol in vol1 vol2 vol3; do
mkdir /mnt/disks/$vol
mount -t tmpfs -o size=5G $vol /mnt/disks/$vol
done
```
The tmpfs method is not recommended for production because the mounts are not
persistent and data will be deleted on reboot.
1. Mount physical disks
```bash
mkdir /mnt/disks/ssd1
mount /dev/vdb1 /mnt/disks/ssd1
```
Physical disks are recommended for production environments because it offers
complete isolation in terms of I/O and capacity.
1. Mount unpartitioned physical devices
```bash
for disk in /dev/sdc /dev/sdd /dev/sde; do
ln -s $disk /mnt/disks
done
```
This saves time of precreating filesystems. Note that your storageclass must have
`volume_mode` set to `"Filesystem"` and `fs_type` defined. If either is not set, the
disk will be added as a raw block device.
1. PersistentVolumes with `volumeMode="Block"`
Just like above, you can create PersistentVolumes with volumeMode `Block`
by creating a symbolic link under discovery directory to the block device on
the node, if you set `volume_mode` to `"Block"`. This will create a volume
presented into a Pod as a block device, without any filesystem on it.
1. File-backed sparsefile method
```bash
truncate /mnt/disks/disk5 --size 2G
mkfs.ext4 /mnt/disks/disk5
mkdir /mnt/disks/vol5
mount /mnt/disks/disk5 /mnt/disks/vol5
```
If you have a development environment and only one disk, this is the best way
to limit the quota of persistent volumes.
1. Simple directories
In a development environment, using `mount --bind` works also, but there is no capacity
management.
## Usage notes
Make sure to make any mounts persist via `/etc/fstab` or with systemd mounts (for
Flatcar Container Linux or Fedora CoreOS). Pods with persistent volume claims will not be
able to start if the mounts become unavailable.
## Further reading
Refer to the upstream docs here: <https://github.com/kubernetes-sigs/sig-storage-local-static-provisioner>