Add GetAccessModes to volume plugin interface

pkg/api/types.go

@@ -195,6 +195,32 @@ type VolumeSource struct {
 	NFS *NFSVolumeSource `json:"nfs"`
 }
 
+// PersistentVolumeSource is similar to VolumeSource but meant for the administrator who creates PVs.
+// Exactly one of its members must be set.
+type PersistentVolumeSource struct {
+	// GCEPersistentDisk represents a GCE Disk resource that is attached to a
+	// kubelet's host machine and then exposed to the pod.
+	GCEPersistentDisk *GCEPersistentDiskVolumeSource `json:"persistentDisk"`
+	// HostPath represents a directory on the host.
+	// This is useful for development and testing only.
+	// on-host storage is not supported in any way
+	HostPath *HostPathVolumeSource `json:"hostPath"`
+	// NFS represents an NFS mount on the host that shares a pod's lifetime
+	NFS *NFSVolumeSource `json:"nfs"`
+}
+
+// used by VolumeSources to describe their mounting/access modes
+type AccessModeType string
+
+const (
+	// can be mounted read/write mode to exactly 1 host
+	ReadWriteOnce AccessModeType = "ReadWriteOnce"
+	// can be mounted in read-only mode to many hosts
+	ReadOnlyMany AccessModeType = "ReadOnlyMany"
+	// can be mounted in read/write mode to many hosts
+	ReadWriteMany AccessModeType = "ReadWriteMany"
+)
+
 // HostPathVolumeSource represents a host directory mapped into a pod.
 type HostPathVolumeSource struct {
 	Path string `json:"path"`

pkg/api/v1beta1/types.go

@@ -109,6 +109,32 @@ type VolumeSource struct {
 	NFS *NFSVolumeSource `json:"nfs" description:"NFS volume that will be mounted in the host machine "`
 }
 
+// PersistentVolumeSource is similar to VolumeSource but meant for the administrator who creates PVs.
+// Exactly one of its members must be set.
+type PersistentVolumeSource struct {
+	// GCEPersistentDisk represents a GCE Disk resource that is attached to a
+	// kubelet's host machine and then exposed to the pod.
+	GCEPersistentDisk *GCEPersistentDiskVolumeSource `json:"persistentDisk" description:"GCE disk resource attached to the host machine on demand"`
+	// HostPath represents a directory on the host.
+	// This is useful for development and testing only.
+	// on-host storage is not supported in any way
+	HostPath *HostPathVolumeSource `json:"hostPath" description:"Persistent hostPath volume useful for development and testing"`
+	// NFS represents an NFS mount on the host that shares a pod's lifetime
+	NFS *NFSVolumeSource `json:"nfs" description:"Persistent NFS volume that will be mounted in the host machine"`
+}
+
+// used by VolumeSources to describe their mounting/access modes
+type AccessModeType string
+
+const (
+	// can be mounted read/write mode to exactly 1 host
+	ReadWriteOnce AccessModeType = "ReadWriteOnce"
+	// can be mounted in read-only mode to many hosts
+	ReadOnlyMany AccessModeType = "ReadOnlyMany"
+	// can be mounted in read/write mode to many hosts
+	ReadWriteMany AccessModeType = "ReadWriteMany"
+)
+
 // HostPathVolumeSource represents bare host directory volume.
 type HostPathVolumeSource struct {
 	Path string `json:"path" description:"path of the directory on the host"`

pkg/api/v1beta2/types.go

@@ -82,6 +82,32 @@ type VolumeSource struct {
 	NFS *NFSVolumeSource `json:"nfs" description:"NFS volume that will be mounted in the host machine"`
 }
 
+// PersistentVolumeSource is similar to VolumeSource but meant for the administrator who creates PVs.
+// Exactly one of its members must be set.
+type PersistentVolumeSource struct {
+	// GCEPersistentDisk represents a GCE Disk resource that is attached to a
+	// kubelet's host machine and then exposed to the pod.
+	GCEPersistentDisk *GCEPersistentDiskVolumeSource `json:"persistentDisk" description:"GCE disk resource attached to the host machine on demand"`
+	// HostPath represents a directory on the host.
+	// This is useful for development and testing only.
+	// on-host storage is not supported in any way
+	HostPath *HostPathVolumeSource `json:"hostPath" description:"Persistent hostPath volume useful for development and testing"`
+	// NFS represents an NFS mount on the host that shares a pod's lifetime
+	NFS *NFSVolumeSource `json:"nfs" description:"Persistent NFS volume that will be mounted in the host machine"`
+}
+
+// used by VolumeSources to describe their mounting/access modes
+type AccessModeType string
+
+const (
+	// can be mounted read/write mode to exactly 1 host
+	ReadWriteOnce AccessModeType = "ReadWriteOnce"
+	// can be mounted in read-only mode to many hosts
+	ReadOnlyMany AccessModeType = "ReadOnlyMany"
+	// can be mounted in read/write mode to many hosts
+	ReadWriteMany AccessModeType = "ReadWriteMany"
+)
+
 // HostPathVolumeSource represents bare host directory volume.
 //
 // https://github.com/GoogleCloudPlatform/kubernetes/blob/master/docs/volumes.md#hostdir

pkg/api/v1beta3/types.go

@@ -214,6 +214,32 @@ type VolumeSource struct {
 	NFS *NFSVolumeSource `json:"nfs" description:"NFS volume that will be mounted in the host machine"`
 }
 
+// PersistentVolumeSource is similar to VolumeSource but meant for the administrator who creates PVs.
+// Exactly one of its members must be set.
+type PersistentVolumeSource struct {
+	// GCEPersistentDisk represents a GCE Disk resource that is attached to a
+	// kubelet's host machine and then exposed to the pod.
+	GCEPersistentDisk *GCEPersistentDiskVolumeSource `json:"persistentDisk" description:"GCE disk resource attached to the host machine on demand"`
+	// HostPath represents a directory on the host.
+	// This is useful for development and testing only.
+	// on-host storage is not supported in any way
+	HostPath *HostPathVolumeSource `json:"hostPath" description:"Persistent hostPath volume useful for development and testing"`
+	// NFS represents an NFS mount on the host that shares a pod's lifetime
+	NFS *NFSVolumeSource `json:"nfs" description:"Persistent NFS volume that will be mounted in the host machine"`
+}
+
+// used by VolumeSources to describe their mounting/access modes
+type AccessModeType string
+
+const (
+	// can be mounted read/write mode to exactly 1 host
+	ReadWriteOnce AccessModeType = "ReadWriteOnce"
+	// can be mounted in read-only mode to many hosts
+	ReadOnlyMany AccessModeType = "ReadOnlyMany"
+	// can be mounted in read/write mode to many hosts
+	ReadWriteMany AccessModeType = "ReadWriteMany"
+)
+
 // HostPathVolumeSource represents bare host directory volume.
 type HostPathVolumeSource struct {
 	Path string `json:"path" description:"path of the directory on the host"`

pkg/volume/gce_pd/gce_pd.go

@@ -71,6 +71,13 @@ func (plugin *gcePersistentDiskPlugin) CanSupport(spec *api.Volume) bool {
 	return false
 }
 
+func (plugin *gcePersistentDiskPlugin) GetAccessModes() []api.AccessModeType {
+	return []api.AccessModeType{
+		api.ReadWriteOnce,
+		api.ReadOnlyMany,
+	}
+}
+
 func (plugin *gcePersistentDiskPlugin) NewBuilder(spec *api.Volume, podRef *api.ObjectReference) (volume.Builder, error) {
 	// Inject real implementations here, test through the internal function.
 	return plugin.newBuilderInternal(spec, podRef.UID, &GCEDiskUtil{}, mount.New())

pkg/volume/gce_pd/gce_pd_test.go

@@ -42,6 +42,28 @@ func TestCanSupport(t *testing.T) {
 	}
 }
 
+func TestGetAccessModes(t *testing.T) {
+	plugMgr := volume.VolumePluginMgr{}
+	plugMgr.InitPlugins(ProbeVolumePlugins(), volume.NewFakeVolumeHost("/tmp/fake", nil, nil))
+
+	plug, err := plugMgr.FindPersistentPluginByName("kubernetes.io/gce-pd")
+	if err != nil {
+		t.Errorf("Can't find the plugin by name")
+	}
+	if !contains(plug.GetAccessModes(), api.ReadWriteOnce) || !contains(plug.GetAccessModes(), api.ReadOnlyMany) {
+		t.Errorf("Expected two AccessModeTypes:  %s and %s", api.ReadWriteOnce, api.ReadOnlyMany)
+	}
+}
+
+func contains(modes []api.AccessModeType, mode api.AccessModeType) bool {
+	for _, m := range modes {
+		if m == mode {
+			return true
+		}
+	}
+	return false
+}
+
 type fakePDManager struct{}
 
 // TODO(jonesdl) To fully test this, we could create a loopback device

pkg/volume/host_path/host_path.go

@@ -54,6 +54,12 @@ func (plugin *hostPathPlugin) CanSupport(spec *api.Volume) bool {
 	return false
 }
 
+func (plugin *hostPathPlugin) GetAccessModes() []api.AccessModeType {
+	return []api.AccessModeType{
+		api.ReadWriteOnce,
+	}
+}
+
 func (plugin *hostPathPlugin) NewBuilder(spec *api.Volume, podRef *api.ObjectReference) (volume.Builder, error) {
 	return &hostPath{spec.HostPath.Path}, nil
 }

pkg/volume/host_path/host_path_test.go

@@ -43,6 +43,19 @@ func TestCanSupport(t *testing.T) {
 	}
 }
 
+func TestGetAccessModes(t *testing.T) {
+	plugMgr := volume.VolumePluginMgr{}
+	plugMgr.InitPlugins(ProbeVolumePlugins(), volume.NewFakeVolumeHost("/tmp/fake", nil, nil))
+
+	plug, err := plugMgr.FindPersistentPluginByName("kubernetes.io/host-path")
+	if err != nil {
+		t.Errorf("Can't find the plugin by name")
+	}
+	if len(plug.GetAccessModes()) != 1 || plug.GetAccessModes()[0] != api.ReadWriteOnce {
+		t.Errorf("Expected %s AccessModeType", api.ReadWriteOnce)
+	}
+}
+
 func TestPlugin(t *testing.T) {
 	plugMgr := volume.VolumePluginMgr{}
 	plugMgr.InitPlugins(ProbeVolumePlugins(), volume.NewFakeVolumeHost("fake", nil, nil))

pkg/volume/nfs/nfs.go

@@ -57,6 +57,14 @@ func (plugin *nfsPlugin) CanSupport(spec *api.Volume) bool {
 	return false
 }
 
+func (plugin *nfsPlugin) GetAccessModes() []api.AccessModeType {
+	return []api.AccessModeType{
+		api.ReadWriteOnce,
+		api.ReadOnlyMany,
+		api.ReadWriteMany,
+	}
+}
+
 func (plugin *nfsPlugin) NewBuilder(spec *api.Volume, podRef *api.ObjectReference) (volume.Builder, error) {
 	return plugin.newBuilderInternal(spec, podRef, plugin.mounter)
 }

pkg/volume/nfs/nfs_test.go

@@ -45,6 +45,28 @@ func TestCanSupport(t *testing.T) {
 	}
 }
 
+func TestGetAccessModes(t *testing.T) {
+	plugMgr := volume.VolumePluginMgr{}
+	plugMgr.InitPlugins(ProbeVolumePlugins(), volume.NewFakeVolumeHost("/tmp/fake", nil, nil))
+
+	plug, err := plugMgr.FindPersistentPluginByName("kubernetes.io/nfs")
+	if err != nil {
+		t.Errorf("Can't find the plugin by name")
+	}
+	if !contains(plug.GetAccessModes(), api.ReadWriteOnce) || !contains(plug.GetAccessModes(), api.ReadOnlyMany) || !contains(plug.GetAccessModes(), api.ReadWriteMany) {
+		t.Errorf("Expected three AccessModeTypes:  %s, %s, and %s", api.ReadWriteOnce, api.ReadOnlyMany, api.ReadWriteMany)
+	}
+}
+
+func contains(modes []api.AccessModeType, mode api.AccessModeType) bool {
+	for _, m := range modes {
+		if m == mode {
+			return true
+		}
+	}
+	return false
+}
+
 type fakeNFSMounter struct {
 	FakeMounter mount.FakeMounter
 }

pkg/volume/plugins.go

@@ -59,6 +59,14 @@ type VolumePlugin interface {
 	NewCleaner(name string, podUID types.UID) (Cleaner, error)
 }
 
+// PersistentVolumePlugin is an extended interface of VolumePlugin and is used
+// by volumes that want to provide long term persistence of data
+type PersistentVolumePlugin interface {
+	VolumePlugin
+	// GetAccessModes describes the ways a given volume can be accessed/mounted.
+	GetAccessModes() []api.AccessModeType
+}
+
 // VolumeHost is an interface that plugins can use to access the kubelet.
 type VolumeHost interface {
 	// GetPluginDir returns the absolute path to a directory under which
@@ -173,3 +181,24 @@ func (pm *VolumePluginMgr) FindPluginByName(name string) (VolumePlugin, error) {
 	}
 	return pm.plugins[matches[0]], nil
 }
+
+// FindPersistentPluginBySpec looks for a plugin that can support a given volume
+// specification.  If no plugins can support or more than one plugin can
+// support it, return error.
+func (pm *VolumePluginMgr) FindPersistentPluginBySpec(spec *api.Volume) (PersistentVolumePlugin, error) {
+	volumePlugin, err := pm.FindPluginBySpec(spec)
+	if err != nil {
+		return nil, err
+	}
+	return volumePlugin.(PersistentVolumePlugin), nil
+}
+
+// FindPluginByName fetches a plugin by name or by legacy name.  If no plugin
+// is found, returns error.
+func (pm *VolumePluginMgr) FindPersistentPluginByName(name string) (PersistentVolumePlugin, error) {
+	volumePlugin, err := pm.FindPluginByName(name)
+	if err != nil {
+		return nil, err
+	}
+	return volumePlugin.(PersistentVolumePlugin), nil
+}

pkg/volume/testing.go

@@ -71,7 +71,7 @@ func (f *fakeVolumeHost) NewWrapperCleaner(spec *api.Volume, podUID types.UID) (
 	return plug.NewCleaner(spec.Name, podUID)
 }
 
-// FakeVolumePlugin is useful for for testing.  It tries to be a fully compliant
+// FakeVolumePlugin is useful for testing.  It tries to be a fully compliant
 // plugin, but all it does is make empty directories.
 // Use as:
 //   volume.RegisterPlugin(&FakePlugin{"fake-name"})
@@ -103,6 +103,10 @@ func (plugin *FakeVolumePlugin) NewCleaner(volName string, podUID types.UID) (Cl
 	return &FakeVolume{podUID, volName, plugin}, nil
 }
 
+func (plugin *FakeVolumePlugin) GetAccessModes() []api.AccessModeType {
+	return []api.AccessModeType{}
+}
+
 type FakeVolume struct {
 	PodUID  types.UID
 	VolName string