Admin Can Specify in Which GCE Availability Zone(s) a PV Shall Be Created

An admin wants to specify in which GCE availability zone(s) users may create persistent volumes using dynamic provisioning.

That's why the admin can now configure in StorageClass object a comma separated list of zones. Dynamically created PVs for PVCs that use the StorageClass are created in one of the configured zones.

examples/persistent-volume-provisioning/README.md

@@ -45,11 +45,12 @@ metadata:
 provisioner: kubernetes.io/gce-pd
 parameters:
   type: pd-standard
-  zone: us-central1-a
+  zones: us-central1-a, us-central1-b
 ```
 
 * `type`: `pd-standard` or `pd-ssd`. Default: `pd-ssd`
-* `zone`: GCE zone. If not specified, a random zone in the same region as controller-manager will be chosen.
+* `zone`: GCE zone. If neither zone nor zones is specified, volumes are generally round-robin-ed across all active zones where Kubernetes cluster has a node. Note: zone and zones parameters must not be used at the same time.
+* `zones`: a comma separated list of GCE zone(s). If neither zone nor zones is specified, volumes are generally round-robin-ed across all active zones where Kubernetes cluster has a node. Note: zone and zones parameters must not be used at the same time.
 
 #### vSphere
 

pkg/volume/gce_pd/gce_util.go

@@ -86,33 +86,55 @@ func (gceutil *GCEDiskUtil) CreateVolume(c *gcePersistentDiskProvisioner) (strin
 	// Apply Parameters (case-insensitive). We leave validation of
 	// the values to the cloud provider.
 	diskType := ""
-	zone := ""
+	configuredZone := ""
+	configuredZones := ""
+	zonePresent := false
+	zonesPresent := false
 	for k, v := range c.options.Parameters {
 		switch strings.ToLower(k) {
 		case "type":
 			diskType = v
 		case "zone":
-			zone = v
+			zonePresent = true
+			configuredZone = v
+		case "zones":
+			zonesPresent = true
+			configuredZones = v
 		default:
 			return "", 0, nil, fmt.Errorf("invalid option %q for volume plugin %s", k, c.plugin.GetPluginName())
 		}
 	}
 
+	if zonePresent && zonesPresent {
+		return "", 0, nil, fmt.Errorf("both zone and zones StorageClass parameters must not be used at the same time")
+	}
+
 	// TODO: implement PVC.Selector parsing
 	if c.options.PVC.Spec.Selector != nil {
 		return "", 0, nil, fmt.Errorf("claim.Spec.Selector is not supported for dynamic provisioning on GCE")
 	}
 
-	if zone == "" {
-		// No zone specified, choose one randomly in the same region as the
-		// node is running.
-		zones, err := cloud.GetAllZones()
+	var zones sets.String
+	if !zonePresent && !zonesPresent {
+		zones, err = cloud.GetAllZones()
 		if err != nil {
 			glog.V(2).Infof("error getting zone information from GCE: %v", err)
 			return "", 0, nil, err
 		}
-		zone = volume.ChooseZoneForVolume(zones, c.options.PVC.Name)
 	}
+	if !zonePresent && zonesPresent {
+		if zones, err = volume.ZonesToSet(configuredZones); err != nil {
+			return "", 0, nil, err
+		}
+	}
+	if zonePresent && !zonesPresent {
+		if err := volume.ValidateZone(configuredZone); err != nil {
+			return "", 0, nil, err
+		}
+		zones = make(sets.String)
+		zones.Insert(configuredZone)
+	}
+	zone := volume.ChooseZoneForVolume(zones, c.options.PVC.Name)
 
 	err = cloud.CreateDisk(name, diskType, zone, int64(requestGB), *c.options.CloudTags)
 	if err != nil {