cinderlib 0.1.0

Cinder Library allows using storage drivers outside of Cinder.

Introduction

Cinder Library is a Python library that allows using storage drivers outside of Cinder.

• Free software: Apache Software License 2.0

• Documentation: https://cinderlib.readthedocs.io.

This library is currently at an Alpha status and is primarily intended as a proof of concept at this stage. While some drivers have been manually validated most drivers have not, so there’s a good chance that they could experience issues.

When using this library one should be aware that this is in no way close to the robustness or feature richness that the Cinder project provides. Some of the more obvious limitations are:

• There are no argument validation on the methods so it’s a classic GIGO library.

• The logic has been kept to a minimum and higher functioning logic is expected to be in the caller. For example you can delete a volume that still has snapshots, and the end results will depend on the Cinder driver and the storage array, so you will have some that will delete the snapshots and others that will leave them there.

• There is no CI, or unit tests for that matter, and certainly nothing so fancy as third party vendor CIs, so things being broken could be considered the norm.

• Only a subset number of basic operations are supported by the library.

The minimum version of Cinder required by this library is Pike; although, depending on my my availability, I may make the library support Ocata as well.

Since it’s using Cinder’s code the library is still bound by the same restrictions and behaviors of the drivers running under the standard Cinder services, which means that not all operations will behave consistently across drivers. For example you can find drivers where cloning is a cheap operation performed by the storage array whereas other will actually create a new volume, attach the source and the new volume and perform a full copy of the data.

If a driver in Cinder requires external libraries or packages they will also be required by the library and will need to be manually installed.

For more detailed information please refer to the official project documentation and OpenStack’s Cinder volume driver configuration documentation.

Due to the limited access to Cinder backends and time constraints the list of drivers that have been manually tested are (I’ll try to test more):

• LVM

• XtremIO

• Kaminario

If you try the library with another storage array I would appreciate a note on the library version, Cinder release, and results of your testing.

Features

• Use a Cinder driver without running a DBMS, Message broker, or Cinder service.

• Using multiple simultaneous drivers on the same program.

• Stateless: Support full serialization of objects and context to json or string so the state can be restored.

• Basic operations support: - Create volume - Delete volume - Extend volume - Clone volume - Create snapshot - Delete snapshot - Create volume from snapshot - Connect volume - Disconnect volume - Local attach - Local detach - Validate connector

Example

The following example uses CentOS 7 and the Cinder LVM driver, which should be the easiest to setup and test.

First you need to setup your system:

# yum install -y centos-release-openstack-pike
# yum install -y openstack-cinder targetcli python-pip
# pip install cinderlib
# dd if=/dev/zero of=cinder-volumes bs=1048576 seek=22527 count=1
# lodevice=`losetup -f`
# losetup $lodevice ./cinder-volumes
# pvcreate $lodevice
# vgcreate cinder-volumes $lodevice
# vgscan --cache

Then you need to run python with a passwordless sudo user (required to control LVM and do the attach) and execute:

import cinderlib as cl
from pprint import pprint as pp

# We setup the library to setup the driver configuration when serializing
cl.setup(output_all_backend_info=True)

# Initialize the LVM driver
lvm = cl.Backend(volume_driver='cinder.volume.drivers.lvm.LVMVolumeDriver',
                 volume_group='cinder-volumes',
                 iscsi_protocol='iscsi',
                 iscsi_helper='lioadm',
                 volume_backend_name='lvm_iscsi')

# Show the LVM backend stats
pp(lvm.stats())

# Create a 1GB volume
vol = lvm.create_volume(1, name='lvm-vol')

# Export, initialize, and do a local attach of the volume
attach = vol.attach()

pp('Volume %s attached to %s' % (vol.id, attach.path))

# Snapshot it
snap = vol.create_snapshot('lvm-snap')

# Save the whole environment to a file
with open('cinderlib-test.txt', 'w') as f:
    f.write(cl.jsons())

# Exit python
exit()

Now we can check that the logical volume is there, exported, and attached to our system:

# lvdisplay
# targetcli ls
# iscsiadm -m session
# lsblk

And now let’s run a new python interpreter and clean things up:

import cinderlib as cl

# Get the whole environment up
with open('cinderlib-test.txt') as f:
    backends = cl.load(f.read())

# Get the volume reference we loaded from file and detach
vol = list(backends[0].volumes)[0]
vol.detach()

# Delete the snapshot and delete it
snap = list(vol.snapshots)[0]
snap.delete()

# Finally delete the volume
vol.delete()

History

0.1.0 (2017-11-03)

• First release on PyPI.