Hi,
I'd like to propose the addition of block-level storage volume management
in LibCloud. In the two environments that I'm familiar with (Amazon EC2 EBS and
Cloudstack volumes), the way of working is very similar, with the main
operations being:
- create storage volume
- attach storage volume to node
- detach storage volume to node
- destroy storage volume
There is currently an closed out-of-date JIRA issue dealing with this issue:
https://issues.apache.org/jira/browse/LIBCLOUD-35. I would propose to use the
general interface outlined in this issue as a starting point, as shown below.
As I'm only familiar with two of the providers that are supported by LibCloud,
and only in a limited way with both of them, I think it would be very useful
to have feedback on the interface outlined below, as well as common use cases
for which this interface may not fit.
I've already added a portion of the interface below to the Cloudstack driver
(https://issues.apache.org/jira/browse/LIBCLOUD-208), and would be happy to
work further on this as well as possibly doing the implementation for EC2 EBS.
Any comments or suggestions would be very welcome.
- Gabriel
#------------------------------------------------------------------------------
class StorageVolume(object):
"""
A base StorageVolume class to derive from.
"""
def __init__(self, id, size, driver, extra=None):
self.id = id
self.size = size
self.driver = driver
self.extra = extra
# The following methods could be added to libcloud.compute.base.NodeDriver:
def create_volume(**kwargs):
"""Create a new volume."""
@keyword size: Size of volume in gigabytes (required)
@type size: C{int}
@keyword name: Name of the volume to be created
@type name: C{str}
@keyword location: Which data center to create a volume in. If empty,
undefined behavoir will be selected. (optional)
@type location: L{NodeLocation}
@keyword snapshot: Name of snapshot from which to create the new
volume. (optional)
@type snapshot: C{str}
@return: The newly created L{StorageVolume}.
"""
raise NotImplementedError(
'create_volume not implemented for this driver')
def destroy_volume(self, volume):
"""Destroys a storage volume
@param volume: Volume to be destroyed
@type volume: L{StorageVolume}
@return: C{bool}
"""
raise NotImplementedError(
'destroy_volume not implemented for this driver')
def attach(self, node, volume, device):
"""Attaches volume to node
@param node: Node to attach volume to
@type node: L{Node}
@param volume: Volume to attach
@type volume: L{StorageVolume}
@param device: Where the device is exposed e.g., (/dev/sdb)
@type device: string
@return: C{bool}
"""
raise NotImplementedError('attach not implemented for this driver')
def detach(self, node, volume):
"""Detaches a volume from a node
@param node: Node from which the volume is to be detached
@type node: L{Node}
@param volume: Volume to be detached
@type volume: L{StorageVolume}
@returns C{bool}
"""
raise NotImplementedError('detach not implemented for this driver')
