4fb8adb9e4
* Makes local volume provisioner more dynamic * Correct variable name in local storage provisioner defaults * Updates external-provisioner readme * Updates variable naming to be more clear, more documentation, fixes sample inventory * Variable refactor, untangled some jinja2 loops * Corrects variable name * No variable substitution in dict keys, replaced with anchor * Fixes default storage_classes dict, inline docs * Fixes spelling in inline docs * Addresses comments in review * Updates all the defaults * Fix failing CI task * Fixes external provisioner daemonset
115 lines
3.3 KiB
Markdown
115 lines
3.3 KiB
Markdown
Local Storage Provisioner
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=========================
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The [local storage provisioner](https://github.com/kubernetes-incubator/external-storage/tree/master/local-volume)
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is NOT a dynamic storage provisioner as you would
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expect from a cloud provider. Instead, it simply creates PersistentVolumes for
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all mounts under the host_dir of the specified storage class.
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These storage classes are specified in the `local_volume_provisioner_storage_classes` list.
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An example this list:
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```yaml
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local_volume_provisioner_storage_classes:
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- local-storage:
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host_dir: /mnt/disks
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mount_dir: /mnt/disks
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- fast-disks:
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host_dir: /mnt/fast-disks
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mount_dir: /mnt/fast-disks
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block_cleaner_command:
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- "/scripts/shred.sh"
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- "2"
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volume_mode: Filesystem
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fs_type: ext4
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```
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For each dictionary in `local_volume_provisioner_storage_classes` a storageClass with the
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same name is created. The keys of this dictionary are converted to camelCase and added
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as attributes to the storageClass.
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The result of the above example is:
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```yaml
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data:
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storageClassMap: |
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local-storage:
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hostDir: /mnt/disks
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mountDir: /mnt/disks
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fast-disks:
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hostDir: /mnt/fast-disks
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mountDir: /mnt/fast-disks
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blockCleanerCommand:
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- "/scripts/shred.sh"
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- "2"
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volumeMode: Filesystem
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fsType: ext4
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```
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The default StorageClass is local-storage on /mnt/disks,
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the rest of this doc will use that path as an example.
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Examples to create local storage volumes
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----------------------------------------
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### tmpfs method:
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``` bash
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for vol in vol1 vol2 vol3; do
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mkdir /mnt/disks/$vol
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mount -t tmpfs -o size=5G $vol /mnt/disks/$vol
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done
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```
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The tmpfs method is not recommended for production because the mount is not
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persistent and data will be deleted on reboot.
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### Mount physical disks
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``` bash
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mkdir /mnt/disks/ssd1
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mount /dev/vdb1 /mnt/disks/ssd1
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```
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Physical disks are recommended for production environments because it offers
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complete isolation in terms of I/O and capacity.
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### File-backed sparsefile method
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``` bash
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truncate /mnt/disks/disk5 --size 2G
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mkfs.ext4 /mnt/disks/disk5
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mkdir /mnt/disks/vol5
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mount /mnt/disks/disk5 /mnt/disks/vol5
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```
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If you have a development environment and only one disk, this is the best way
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to limit the quota of persistent volumes.
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### Simple directories
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In a development environment using `mount --bind` works also, but there is no capacity
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management.
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### Block volumeMode PVs
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Create a symbolic link under discovery directory to the block device on the node. To use
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raw block devices in pods BlockVolume feature gate must be enabled.
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Usage notes
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-----------
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Beta PV.NodeAffinity field is used by default. If running against an older K8s
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version, the useAlphaAPI flag must be set in the configMap.
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The volume provisioner cannot calculate volume sizes correctly, so you should
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delete the daemonset pod on the relevant host after creating volumes. The pod
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will be recreated and read the size correctly.
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Make sure to make any mounts persist via /etc/fstab or with systemd mounts (for
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CoreOS/Container Linux). Pods with persistent volume claims will not be
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able to start if the mounts become unavailable.
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Further reading
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---------------
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Refer to the upstream docs here: <https://github.com/kubernetes-incubator/external-storage/tree/master/local-volume>
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