volume.go

/*
Copyright 2016 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package controller

import (
	"fmt"

	"k8s.io/api/core/v1"
)

// Provisioner is an interface that creates templates for PersistentVolumes
// and can create the volume as a new resource in the infrastructure provider.
// It can also remove the volume it created from the underlying storage
// provider.
type Provisioner interface {
	// Provision creates a volume i.e. the storage asset and returns a PV object
	// for the volume
	Provision(VolumeOptions) (*v1.PersistentVolume, error)
	// Delete removes the storage asset that was created by Provision backing the
	// given PV. Does not delete the PV object itself.
	//
	// May return IgnoredError to indicate that the call has been ignored and no
	// action taken.
	Delete(*v1.PersistentVolume) error
}

// Qualifier is an optional interface implemented by provisioners to determine
// whether a claim should be provisioned as early as possible (e.g. prior to
// leader election).
type Qualifier interface {
	// ShouldProvision returns whether provisioning for the claim should
	// be attempted.
	ShouldProvision(*v1.PersistentVolumeClaim) bool
}

// BlockProvisioner is an optional interface implemented by provisioners to determine
// whether it supports block volume.
type BlockProvisioner interface {
	Provisioner
	// SupportsBlock returns whether provisioner supports block volume.
	SupportsBlock() bool
}

// IgnoredError is the value for Delete to return to indicate that the call has
// been ignored and no action taken. In case multiple provisioners are serving
// the same storage class, provisioners may ignore PVs they are not responsible
// for (e.g. ones they didn't create). The controller will act accordingly,
// i.e. it won't emit a misleading VolumeFailedDelete event.
type IgnoredError struct {
	Reason string
}

func (e *IgnoredError) Error() string {
	return fmt.Sprintf("ignored because %s", e.Reason)
}

// VolumeOptions contains option information about a volume
// https://github.com/kubernetes/kubernetes/blob/release-1.4/pkg/volume/plugins.go
type VolumeOptions struct {
	// Reclamation policy for a persistent volume
	PersistentVolumeReclaimPolicy v1.PersistentVolumeReclaimPolicy
	// PV.Name of the appropriate PersistentVolume. Used to generate cloud
	// volume name.
	PVName string

	// PV mount options. Not validated - mount of the PVs will simply fail if one is invalid.
	MountOptions []string

	// PVC is reference to the claim that lead to provisioning of a new PV.
	// Provisioners *must* create a PV that would be matched by this PVC,
	// i.e. with required capacity, accessMode, labels matching PVC.Selector and
	// so on.
	PVC *v1.PersistentVolumeClaim
	// Volume provisioning parameters from StorageClass
	Parameters map[string]string

	// Node selected by the scheduler for the volume.
	SelectedNode *v1.Node
	// Topology constraint parameter from StorageClass
	AllowedTopologies []v1.TopologySelectorTerm
}