Added volume.Creater interface and simple HostPath implementation

pkg/volume/host_path/host_path.go

@@ -22,7 +22,9 @@ import (
 	"regexp"
 
 	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/api/resource"
 	"k8s.io/kubernetes/pkg/types"
+	"k8s.io/kubernetes/pkg/util"
 	"k8s.io/kubernetes/pkg/volume"
 )
 
@@ -36,6 +38,7 @@ func ProbeVolumePlugins(volumeConfig volume.VolumeConfig) []volume.VolumePlugin
 			host:            nil,
 			newRecyclerFunc: newRecycler,
 			newDeleterFunc:  newDeleter,
+			newCreaterFunc:  newCreater,
 			config:          volumeConfig,
 		},
 	}
@@ -46,6 +49,7 @@ func ProbeRecyclableVolumePlugins(recyclerFunc func(spec *volume.Spec, host volu
 		&hostPathPlugin{
 			host:            nil,
 			newRecyclerFunc: recyclerFunc,
+			newCreaterFunc:  newCreater,
 			config:          volumeConfig,
 		},
 	}
@@ -53,17 +57,18 @@ func ProbeRecyclableVolumePlugins(recyclerFunc func(spec *volume.Spec, host volu
 
 type hostPathPlugin struct {
 	host volume.VolumeHost
-	// decouple creating recyclers by deferring to a function.  Allows for easier testing.
+	// decouple creating Recyclers/Deleters/Creaters by deferring to a function.  Allows for easier testing.
 	newRecyclerFunc func(spec *volume.Spec, host volume.VolumeHost, volumeConfig volume.VolumeConfig) (volume.Recycler, error)
-	// decouple creating deleters by deferring to a function.  Allows for easier testing.
+	newDeleterFunc  func(spec *volume.Spec, host volume.VolumeHost) (volume.Deleter, error)
-	newDeleterFunc func(spec *volume.Spec, host volume.VolumeHost) (volume.Deleter, error)
+	newCreaterFunc  func(options volume.VolumeOptions, host volume.VolumeHost) (volume.Creater, error)
-	config         volume.VolumeConfig
+	config          volume.VolumeConfig
 }
 
 var _ volume.VolumePlugin = &hostPathPlugin{}
 var _ volume.PersistentVolumePlugin = &hostPathPlugin{}
 var _ volume.RecyclableVolumePlugin = &hostPathPlugin{}
 var _ volume.DeletableVolumePlugin = &hostPathPlugin{}
+var _ volume.CreatableVolumePlugin = &hostPathPlugin{}
 
 const (
 	hostPathPluginName = "kubernetes.io/host-path"
@@ -114,6 +119,10 @@ func (plugin *hostPathPlugin) NewDeleter(spec *volume.Spec) (volume.Deleter, err
 	return plugin.newDeleterFunc(spec, plugin.host)
 }
 
+func (plugin *hostPathPlugin) NewCreater(options volume.VolumeOptions) (volume.Creater, error) {
+	return plugin.newCreaterFunc(options, plugin.host)
+}
+
 func newRecycler(spec *volume.Spec, host volume.VolumeHost, config volume.VolumeConfig) (volume.Recycler, error) {
 	if spec.PersistentVolume == nil || spec.PersistentVolume.Spec.HostPath == nil {
 		return nil, fmt.Errorf("spec.PersistentVolumeSource.HostPath is nil")
@@ -134,6 +143,10 @@ func newDeleter(spec *volume.Spec, host volume.VolumeHost) (volume.Deleter, erro
 	return &hostPathDeleter{spec.Name(), spec.PersistentVolume.Spec.HostPath.Path, host}, nil
 }
 
+func newCreater(options volume.VolumeOptions, host volume.VolumeHost) (volume.Creater, error) {
+	return &hostPathCreater{options: options, host: host}, nil
+}
+
 // HostPath volumes represent a bare host file or directory mount.
 // The direct at the specified path will be directly exposed to the container.
 type hostPath struct {
@@ -185,8 +198,8 @@ func (c *hostPathCleaner) TearDownAt(dir string) error {
 	return fmt.Errorf("TearDownAt() does not make sense for host paths")
 }
 
-// hostPathRecycler scrubs a hostPath volume by running "rm -rf" on the volume in a pod
+// hostPathRecycler implements a dynamic provisioning Recycler for the HostPath plugin
-// This recycler only works on a single host cluster and is for testing purposes only.
+// This implementation is meant for testing only and only works in a single node cluster
 type hostPathRecycler struct {
 	name    string
 	path    string
@@ -215,6 +228,42 @@ func (r *hostPathRecycler) Recycle() error {
 	return volume.RecycleVolumeByWatchingPodUntilCompletion(pod, r.host.GetKubeClient())
 }
 
+// hostPathCreater implements a dynamic provisioning Creater for the HostPath plugin
+// This implementation is meant for testing only and only works in a single node cluster.
+type hostPathCreater struct {
+	host    volume.VolumeHost
+	options volume.VolumeOptions
+}
+
+// Create for hostPath simply creates a local /tmp/hostpath_pv/%s directory as a new PersistentVolume.
+// This Creater is meant for development and testing only and WILL NOT WORK in a multi-node cluster.
+func (r *hostPathCreater) Create() (*api.PersistentVolume, error) {
+	fullpath := fmt.Sprintf("/tmp/hostpath_pv/%s", util.NewUUID())
+	err := os.MkdirAll(fullpath, 0750)
+	if err != nil {
+		return nil, err
+	}
+
+	return &api.PersistentVolume{
+		ObjectMeta: api.ObjectMeta{
+			GenerateName: "pv-hostpath-",
+			Labels: map[string]string{
+				"createdby": "hostpath dynamic provisioner",
+			},
+		},
+		Spec: api.PersistentVolumeSpec{
+			Capacity: api.ResourceList{
+				api.ResourceName(api.ResourceStorage): resource.MustParse(fmt.Sprintf("%dMi", r.options.CapacityMB)),
+			},
+			PersistentVolumeSource: api.PersistentVolumeSource{
+				HostPath: &api.HostPathVolumeSource{
+					Path: fullpath,
+				},
+			},
+		},
+	}, nil
+}
+
 // hostPathDeleter deletes a hostPath PV from the cluster.
 // This deleter only works on a single host cluster and is for testing purposes only.
 type hostPathDeleter struct {

pkg/volume/host_path/host_path_test.go

@@ -67,7 +67,7 @@ func TestGetAccessModes(t *testing.T) {
 func TestRecycler(t *testing.T) {
 	plugMgr := volume.VolumePluginMgr{}
 	pluginHost := volume.NewFakeVolumeHost("/tmp/fake", nil, nil)
-	plugMgr.InitPlugins([]volume.VolumePlugin{&hostPathPlugin{nil, volume.NewFakeRecycler, nil, volume.VolumeConfig{}}}, pluginHost)
+	plugMgr.InitPlugins([]volume.VolumePlugin{&hostPathPlugin{nil, volume.NewFakeRecycler, nil, nil, volume.VolumeConfig{}}}, pluginHost)
 
 	spec := &volume.Spec{PersistentVolume: &api.PersistentVolume{Spec: api.PersistentVolumeSpec{PersistentVolumeSource: api.PersistentVolumeSource{HostPath: &api.HostPathVolumeSource{Path: "/foo"}}}}}
 	plug, err := plugMgr.FindRecyclablePluginBySpec(spec)
@@ -143,6 +143,32 @@ func TestDeleterTempDir(t *testing.T) {
 	}
 }
 
+func TestCreater(t *testing.T) {
+	tempPath := "/tmp/hostpath/"
+	defer os.RemoveAll(tempPath)
+	err := os.MkdirAll(tempPath, 0750)
+
+	plugMgr := volume.VolumePluginMgr{}
+	plugMgr.InitPlugins(ProbeVolumePlugins(volume.VolumeConfig{}), volume.NewFakeVolumeHost("/tmp/fake", nil, nil))
+	spec := &volume.Spec{PersistentVolume: &api.PersistentVolume{Spec: api.PersistentVolumeSpec{PersistentVolumeSource: api.PersistentVolumeSource{HostPath: &api.HostPathVolumeSource{Path: tempPath}}}}}
+	plug, err := plugMgr.FindCreatablePluginBySpec(spec)
+	if err != nil {
+		t.Errorf("Can't find the plugin by name")
+	}
+	creater, err := plug.NewCreater(volume.VolumeOptions{CapacityMB: 100})
+	if err != nil {
+		t.Errorf("Failed to make a new Creater: %v", err)
+	}
+	pv, err := creater.Create()
+	if err != nil {
+		t.Errorf("Unexpected error creating volume: %v", err)
+	}
+	if pv.Spec.HostPath.Path == "" {
+		t.Errorf("Expected pv.Spec.HostPath.Path to not be empty: %#v", pv)
+	}
+	os.RemoveAll(pv.Spec.HostPath.Path)
+}
+
 func TestPlugin(t *testing.T) {
 	plugMgr := volume.VolumePluginMgr{}
 	plugMgr.InitPlugins(ProbeVolumePlugins(volume.VolumeConfig{}), volume.NewFakeVolumeHost("fake", nil, nil))

pkg/volume/plugins.go

@@ -33,14 +33,13 @@ import (
 )
 
 // VolumeOptions contains option information about a volume.
-//
-// Currently, this struct containers only a single field for the
-// rootcontext of the volume.  This is a temporary measure in order
-// to set the rootContext of tmpfs mounts correctly; it will be replaced
-// and expanded on by future SecurityContext work.
 type VolumeOptions struct {
 	// The rootcontext to use when performing mounts for a volume.
+	// This is a temporary measure in order to set the rootContext of tmpfs mounts correctly.
+	// it will be replaced and expanded on by future SecurityContext work.
 	RootContext string
+	// CapacityMB is the size in MB of a volume.
+	CapacityMB int
 }
 
 // VolumePlugin is an interface to volume plugins that can be used on a
@@ -99,6 +98,14 @@ type DeletableVolumePlugin interface {
 	NewDeleter(spec *Spec) (Deleter, error)
 }
 
+// CreatableVolumePlugin is an extended interface of VolumePlugin and is used to create persistent volumes for the cluster.
+type CreatableVolumePlugin interface {
+	VolumePlugin
+	// NewCreater creates a new volume.Creater which knows how to create PersistentVolumes in accordance with
+	// the plugin's underlying storage provider
+	NewCreater(options VolumeOptions) (Creater, error)
+}
+
 // 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
@@ -345,6 +352,19 @@ func (pm *VolumePluginMgr) FindDeletablePluginBySpec(spec *Spec) (DeletableVolum
 	return nil, fmt.Errorf("no deletable volume plugin matched")
 }
 
+// FindCreatablePluginBySpec fetches a persistent volume plugin by name.  If no plugin
+// is found, returns error.
+func (pm *VolumePluginMgr) FindCreatablePluginBySpec(spec *Spec) (CreatableVolumePlugin, error) {
+	volumePlugin, err := pm.FindPluginBySpec(spec)
+	if err != nil {
+		return nil, err
+	}
+	if creatableVolumePlugin, ok := volumePlugin.(CreatableVolumePlugin); ok {
+		return creatableVolumePlugin, nil
+	}
+	return nil, fmt.Errorf("no creatable volume plugin matched")
+}
+
 // NewPersistentVolumeRecyclerPodTemplate creates a template for a recycler pod.  By default, a recycler pod simply runs
 // "rm -rf" on a volume and tests for emptiness.  Most attributes of the template will be correct for most
 // plugin implementations.  The following attributes can be overridden per plugin via configuration:

pkg/volume/volume.go

@@ -18,6 +18,7 @@ package volume
 
 import (
 	"io/ioutil"
+	"k8s.io/kubernetes/pkg/api"
 	"os"
 	"path"
 )
@@ -65,6 +66,12 @@ type Recycler interface {
 	Recycle() error
 }
 
+// Create adds a new resource in the storage provider and creates a PersistentVolume for the new resource.
+// Calls to Create should block until complete.
+type Creater interface {
+	Create() (*api.PersistentVolume, error)
+}
+
 // Delete removes the resource from the underlying storage provider.  Calls to this method should block until
 // the deletion is complete. Any error returned indicates the volume has failed to be reclaimed.
 // A nil return indicates success.