Portworx Volume Driver in Kubernetes

- Add a new type PortworxVolumeSource
- Implement the kubernetes volume plugin for Portworx Volumes under pkg/volume/portworx
- The Portworx Volume Driver uses the libopenstorage/openstorage specifications and apis for volume operations.

Changes for k8s configuration and examples for portworx volumes.

- Add PortworxVolume hooks in kubectl, kube-controller-manager and validation.
- Add a README for PortworxVolume usage as PVs, PVCs and StorageClass.
- Add example spec files

Handle code review comments.

- Modified READMEs to incorporate to suggestions.
- Add a test for ReadWriteMany access mode.
- Use util.UnmountPath in TearDown.
- Add ReadOnly flag to PortworxVolumeSource
- Use hostname:port instead of unix sockets
- Delete the mount dir in TearDown.
- Fix link issue in persistentvolumes README
- In unit test check for mountpath after Setup is done.
- Add PVC Claim Name as a Portworx Volume Label

Generated code and documentation.
- Updated swagger spec
- Updated api-reference docs
- Updated generated code under pkg/api/v1

Godeps update for Portworx Volume Driver
- Adds github.com/libopenstorage/openstorage
- Adds go.pedge.io/pb/go/google/protobuf
- Updates Godep Licenses

vendor/github.com/libopenstorage/openstorage/volume/volume.go

@@ -0,0 +1,171 @@
+package volume
+
+import (
+	"errors"
+
+	"github.com/libopenstorage/openstorage/api"
+)
+
+var (
+	ErrAlreadyShutdown         = errors.New("VolumeDriverProvider already shutdown")
+	ErrExist                   = errors.New("Driver already exists")
+	ErrDriverNotFound          = errors.New("Driver implementation not found")
+	ErrDriverInitializing      = errors.New("Driver is initializing")
+	ErrEnoEnt                  = errors.New("Volume does not exist.")
+	ErrEnomem                  = errors.New("Out of memory.")
+	ErrEinval                  = errors.New("Invalid argument")
+	ErrVolDetached             = errors.New("Volume is detached")
+	ErrVolAttached             = errors.New("Volume is attached")
+	ErrVolAttachedOnRemoteNode = errors.New("Volume is attached on another node")
+	ErrVolAttachedScale        = errors.New("Volume is attached but can be scaled")
+	ErrVolHasSnaps             = errors.New("Volume has snapshots associated")
+	ErrNotSupported            = errors.New("Operation not supported")
+)
+
+// Constants used by the VolumeDriver
+const (
+	APIVersion    = "v1"
+	PluginAPIBase = "/run/docker/plugins/"
+	DriverAPIBase = "/var/lib/osd/driver/"
+	MountBase     = "/var/lib/osd/mounts/"
+	VolumeBase    = "/var/lib/osd/"
+)
+
+type Store interface {
+	// Lock volume specified by volumeID.
+	Lock(volumeID string) (interface{}, error)
+	// Lock volume with token obtained from call to Lock.
+	Unlock(token interface{}) error
+	// CreateVol returns error if volume with the same ID already existe.
+	CreateVol(vol *api.Volume) error
+	// GetVol from volumeID.
+	GetVol(volumeID string) (*api.Volume, error)
+	// UpdateVol with vol
+	UpdateVol(vol *api.Volume) error
+	// DeleteVol. Returns error if volume does not exist.
+	DeleteVol(volumeID string) error
+}
+
+// VolumeDriver is the main interface to be implemented by any storage driver.
+// Every driver must at minimum implement the ProtoDriver sub interface.
+type VolumeDriver interface {
+	IODriver
+	ProtoDriver
+	BlockDriver
+	Enumerator
+}
+
+// IODriver interfaces applicable to object store interfaces.
+type IODriver interface {
+	// Read sz bytes from specified volume at specified offset.
+	// Return number of bytes read and error.
+	Read(volumeID string, buf []byte, sz uint64, offset int64) (int64, error)
+	// Write sz bytes from specified volume at specified offset.
+	// Return number of bytes written and error.
+	Write(volumeID string, buf []byte, sz uint64, offset int64) (int64, error)
+	// Flush writes to stable storage.
+	// Return error.
+	Flush(volumeID string) error
+}
+
+type SnapshotDriver interface {
+	// Snapshot create volume snapshot.
+	// Errors ErrEnoEnt may be returned
+	Snapshot(volumeID string, readonly bool, locator *api.VolumeLocator) (string, error)
+}
+
+// ProtoDriver must be implemented by all volume drivers.  It specifies the
+// most basic functionality, such as creating and deleting volumes.
+type ProtoDriver interface {
+	SnapshotDriver
+	// Name returns the name of the driver.
+	Name() string
+	// Type of this driver
+	Type() api.DriverType
+	// Create a new Vol for the specific volume spec.
+	// It returns a system generated VolumeID that uniquely identifies the volume
+	Create(locator *api.VolumeLocator, Source *api.Source, spec *api.VolumeSpec) (string, error)
+	// Delete volume.
+	// Errors ErrEnoEnt, ErrVolHasSnaps may be returned.
+	Delete(volumeID string) error
+	// Mount volume at specified path
+	// Errors ErrEnoEnt, ErrVolDetached may be returned.
+	Mount(volumeID string, mountPath string) error
+	// MountedAt return volume mounted at specified mountpath.
+	MountedAt(mountPath string) string
+	// Unmount volume at specified path
+	// Errors ErrEnoEnt, ErrVolDetached may be returned.
+	Unmount(volumeID string, mountPath string) error
+	// Update not all fields of the spec are supported, ErrNotSupported will be thrown for unsupported
+	// updates.
+	Set(volumeID string, locator *api.VolumeLocator, spec *api.VolumeSpec) error
+	// Stats for specified volume.
+	// cumulative stats are /proc/diskstats style stats.
+	// nonCumulative stats are stats for specific duration.
+	// Errors ErrEnoEnt may be returned
+	Stats(volumeID string, cumulative bool) (*api.Stats, error)
+	// Alerts on this volume.
+	// Errors ErrEnoEnt may be returned
+	Alerts(volumeID string) (*api.Alerts, error)
+	// GetActiveRequests get active requests
+	GetActiveRequests() (*api.ActiveRequests, error)
+	// Status returns a set of key-value pairs which give low
+	// level diagnostic status about this driver.
+	Status() [][2]string
+	// Shutdown and cleanup.
+	Shutdown()
+}
+
+// Enumerator provides a set of interfaces to get details on a set of volumes.
+type Enumerator interface {
+	// Inspect specified volumes.
+	// Returns slice of volumes that were found.
+	Inspect(volumeIDs []string) ([]*api.Volume, error)
+	// Enumerate volumes that map to the volumeLocator. Locator fields may be regexp.
+	// If locator fields are left blank, this will return all volumes.
+	Enumerate(locator *api.VolumeLocator, labels map[string]string) ([]*api.Volume, error)
+	// Enumerate snaps for specified volumes
+	SnapEnumerate(volID []string, snapLabels map[string]string) ([]*api.Volume, error)
+}
+
+type StoreEnumerator interface {
+	Store
+	Enumerator
+}
+
+// BlockDriver needs to be implemented by block volume drivers.  Filesystem volume
+// drivers can ignore this interface and include the builtin DefaultBlockDriver.
+type BlockDriver interface {
+	// Attach map device to the host.
+	// On success the devicePath specifies location where the device is exported
+	// Errors ErrEnoEnt, ErrVolAttached may be returned.
+	Attach(volumeID string) (string, error)
+	// Detach device from the host.
+	// Errors ErrEnoEnt, ErrVolDetached may be returned.
+	Detach(volumeID string) error
+}
+
+// VolumeDriverProvider provides VolumeDrivers.
+type VolumeDriverProvider interface {
+	// Get gets the VolumeDriver for the given name.
+	// If a VolumeDriver was not created for the given name, the error ErrDriverNotFound is returned.
+	Get(name string) (VolumeDriver, error)
+	// Shutdown shuts down all volume drivers.
+	Shutdown() error
+}
+
+// VolumeDriverRegistry registers VolumeDrivers.
+type VolumeDriverRegistry interface {
+	VolumeDriverProvider
+	// New creates the VolumeDriver for the given name.
+	// If a VolumeDriver was already created for the given name, the error ErrExist is returned.
+	Register(name string, params map[string]string) error
+
+	// Add inserts a new VolumeDriver provider with a well known name.
+	Add(name string, init func(map[string]string) (VolumeDriver, error)) error
+}
+
+// VolumeDriverRegistry constructs a new VolumeDriverRegistry.
+func NewVolumeDriverRegistry(nameToInitFunc map[string]func(map[string]string) (VolumeDriver, error)) VolumeDriverRegistry {
+	return newVolumeDriverRegistry(nameToInitFunc)
+}