Tim Bannister
9c0c75e0f2
Introduce concepts in an order that should suit people new to Kubernetes, so that you don't encounter details like volume cloning until you've seen more of the basic volume types (persistent, ephemeral, projected).
86 lines
2.7 KiB
Markdown
86 lines
2.7 KiB
Markdown
---
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reviewers:
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- saad-ali
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- thockin
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- msau42
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- jingxu97
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- xing-yang
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- yuxiangqian
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title: Volume Snapshot Classes
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content_type: concept
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weight: 41 # just after volume snapshots
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---
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<!-- overview -->
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This document describes the concept of VolumeSnapshotClass in Kubernetes. Familiarity
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with [volume snapshots](/docs/concepts/storage/volume-snapshots/) and
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[storage classes](/docs/concepts/storage/storage-classes) is suggested.
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<!-- body -->
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## Introduction
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Just like StorageClass provides a way for administrators to describe the "classes"
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of storage they offer when provisioning a volume, VolumeSnapshotClass provides a
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way to describe the "classes" of storage when provisioning a volume snapshot.
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## The VolumeSnapshotClass Resource
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Each VolumeSnapshotClass contains the fields `driver`, `deletionPolicy`, and `parameters`,
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which are used when a VolumeSnapshot belonging to the class needs to be
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dynamically provisioned.
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The name of a VolumeSnapshotClass object is significant, and is how users can
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request a particular class. Administrators set the name and other parameters
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of a class when first creating VolumeSnapshotClass objects, and the objects cannot
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be updated once they are created.
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```yaml
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apiVersion: snapshot.storage.k8s.io/v1
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kind: VolumeSnapshotClass
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metadata:
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name: csi-hostpath-snapclass
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driver: hostpath.csi.k8s.io
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deletionPolicy: Delete
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parameters:
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```
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Administrators can specify a default VolumeSnapshotClass for VolumeSnapshots
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that don't request any particular class to bind to by adding the
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`snapshot.storage.kubernetes.io/is-default-class: "true"` annotation:
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```yaml
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apiVersion: snapshot.storage.k8s.io/v1
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kind: VolumeSnapshotClass
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metadata:
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name: csi-hostpath-snapclass
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annotations:
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snapshot.storage.kubernetes.io/is-default-class: "true"
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driver: hostpath.csi.k8s.io
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deletionPolicy: Delete
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parameters:
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```
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### Driver
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Volume snapshot classes have a driver that determines what CSI volume plugin is
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used for provisioning VolumeSnapshots. This field must be specified.
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### DeletionPolicy
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Volume snapshot classes have a deletionPolicy. It enables you to configure what happens to a VolumeSnapshotContent when the VolumeSnapshot object it is bound to is to be deleted. The deletionPolicy of a volume snapshot class can either be `Retain` or `Delete`. This field must be specified.
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If the deletionPolicy is `Delete`, then the underlying storage snapshot will be deleted along with the VolumeSnapshotContent object. If the deletionPolicy is `Retain`, then both the underlying snapshot and VolumeSnapshotContent remain.
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## Parameters
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Volume snapshot classes have parameters that describe volume snapshots belonging to
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the volume snapshot class. Different parameters may be accepted depending on the
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`driver`.
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