Add custom volumename option to GlusterFS dynamic PVs.

At present glusterfs dynamic PVs are created with
random names. However an admin would like to have some
handle on the volume names created dynamically for
various purposes. One example would be having a filter
for sorting out PVs created for a particular storage class.

This patch enables the functionality by having a custom
volume name as a prefix to dynamic PVs. This is an optional
parameter in SC and if set, the dynamic volumes are created
in below format where `_` is the field seperator/delimiter:

customvolumeprefix_PVCname_randomUUID

Signed-off-by: Humble Chirammal <hchiramm@redhat.com>

pkg/volume/glusterfs/glusterfs.go

@@ -36,6 +36,7 @@ import (
 	"k8s.io/apimachinery/pkg/labels"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/sets"
+	"k8s.io/apimachinery/pkg/util/uuid"
 	clientset "k8s.io/client-go/kubernetes"
 	v1helper "k8s.io/kubernetes/pkg/apis/core/v1/helper"
 	"k8s.io/kubernetes/pkg/util/mount"
@@ -406,17 +407,18 @@ func (plugin *glusterfsPlugin) newProvisionerInternal(options volume.VolumeOptio
 }
 
 type provisionerConfig struct {
-	url             string
-	user            string
-	userKey         string
-	secretNamespace string
-	secretName      string
-	secretValue     string
-	clusterID       string
-	gidMin          int
-	gidMax          int
-	volumeType      gapi.VolumeDurabilityInfo
-	volumeOptions   []string
+	url              string
+	user             string
+	userKey          string
+	secretNamespace  string
+	secretName       string
+	secretValue      string
+	clusterID        string
+	gidMin           int
+	gidMax           int
+	volumeType       gapi.VolumeDurabilityInfo
+	volumeOptions    []string
+	volumeNamePrefix string
 }
 
 type glusterfsVolumeProvisioner struct {
@@ -743,6 +745,7 @@ func (p *glusterfsVolumeProvisioner) Provision() (*v1.PersistentVolume, error) {
 
 func (p *glusterfsVolumeProvisioner) CreateVolume(gid int) (r *v1.GlusterfsVolumeSource, size int, volID string, err error) {
 	var clusterIDs []string
+	customVolumeName := ""
 	capacity := p.options.PVC.Spec.Resources.Requests[v1.ResourceName(v1.ResourceStorage)]
 	// Glusterfs creates volumes in units of GiB, but heketi documentation incorrectly reports GBs
 	sz := int(volume.RoundUpToGiB(capacity))
@@ -760,8 +763,13 @@ func (p *glusterfsVolumeProvisioner) CreateVolume(gid int) (r *v1.GlusterfsVolum
 		clusterIDs = dstrings.Split(p.clusterID, ",")
 		glog.V(4).Infof("provided clusterIDs: %v", clusterIDs)
 	}
+
+	if p.provisionerConfig.volumeNamePrefix != "" {
+		customVolumeName = fmt.Sprintf("%s_%s_%s", p.provisionerConfig.volumeNamePrefix, p.options.PVC.Name, uuid.NewUUID())
+	}
+
 	gid64 := int64(gid)
-	volumeReq := &gapi.VolumeCreateRequest{Size: sz, Clusters: clusterIDs, Gid: gid64, Durability: p.volumeType, GlusterVolumeOptions: p.volumeOptions}
+	volumeReq := &gapi.VolumeCreateRequest{Size: sz, Name: customVolumeName, Clusters: clusterIDs, Gid: gid64, Durability: p.volumeType, GlusterVolumeOptions: p.volumeOptions}
 	volume, err := cli.VolumeCreate(volumeReq)
 	if err != nil {
 		glog.Errorf("error creating volume %v ", err)
@@ -927,6 +935,7 @@ func parseClassParameters(params map[string]string, kubeClient clientset.Interfa
 	authEnabled := true
 	parseVolumeType := ""
 	parseVolumeOptions := ""
+	parseVolumeNamePrefix := ""
 
 	for k, v := range params {
 		switch dstrings.ToLower(k) {
@@ -977,7 +986,10 @@ func parseClassParameters(params map[string]string, kubeClient clientset.Interfa
 			if len(v) != 0 {
 				parseVolumeOptions = v
 			}
-
+		case "volumenameprefix":
+			if len(v) != 0 {
+				parseVolumeNamePrefix = v
+			}
 		default:
 			return nil, fmt.Errorf("invalid option %q for volume plugin %s", k, glusterfsPluginName)
 		}
@@ -1057,6 +1069,13 @@ func parseClassParameters(params map[string]string, kubeClient clientset.Interfa
 		cfg.volumeOptions = volOptions
 
 	}
+
+	if len(parseVolumeNamePrefix) != 0 {
+		if dstrings.Contains(parseVolumeNamePrefix, "_") {
+			return nil, fmt.Errorf("Storageclass parameter 'volumenameprefix' should not contain '_' in its value")
+		}
+		cfg.volumeNamePrefix = parseVolumeNamePrefix
+	}
 	return &cfg, nil
 }