csi: use publish_info for storing and accessing the volume name

This does away with the need for the nodes to call the API to fetch the
volume name, when it can be stored in the Status.AttachmentMetadata of
the VolumeAttachment object.

driver/controller.go

@@ -41,6 +41,8 @@ const (
 )
 
 const (
+ PublishInfoVolumeName = "com.digitalocean.csi/volume-name"
+
  defaultVolumeSizeInGB = 16 * GB
 
  createdByDO = "Created by DigitalOcean CSI driver"
@@ -253,7 +255,11 @@ func (d *Driver) ControllerPublishVolume(ctx context.Context, req *csi.Controlle
  attachedID = id
  if id == dropletID {
  ll.Info("volume is already attached")
- return &csi.ControllerPublishVolumeResponse{}, nil
+ return &csi.ControllerPublishVolumeResponse{
+ PublishInfo: map[string]string{
+ PublishInfoVolumeName: vol.Name,
+ },
+ }, nil
  }
  }
 
@@ -273,7 +279,11 @@ func (d *Driver) ControllerPublishVolume(ctx context.Context, req *csi.Controlle
  "error": err,
  "resp": resp,
  }).Warn("assuming volume is attached already")
- return &csi.ControllerPublishVolumeResponse{}, nil
+ return &csi.ControllerPublishVolumeResponse{
+ PublishInfo: map[string]string{
+ PublishInfoVolumeName: vol.Name,
+ },
+ }, nil
  }
 
  if strings.Contains(err.Error(), "Droplet already has a pending event") {
@@ -297,7 +307,11 @@ func (d *Driver) ControllerPublishVolume(ctx context.Context, req *csi.Controlle
  }
 
  ll.Info("volume is attached")
- return &csi.ControllerPublishVolumeResponse{}, nil
+ return &csi.ControllerPublishVolumeResponse{
+ PublishInfo: map[string]string{
+ PublishInfoVolumeName: vol.Name,
+ },
+ }, nil
 }
 
 // ControllerUnpublishVolume deattaches the given volume from the node